Survival outcomes in elderly Taiwanese women according to breast cancer subtype and lymph node status: A single-center retrospective study.

This study aimed to determine the rates of overall survival and recurrence-free survival among elderly Taiwanese women (>65 years old) according to breast cancer subtype and lymph node status. We identified 554 eligible patients who were >65 years old and had been treated based on international recommendations at our center between June 2005 and June 2015. Patients with the luminal A subtype had the highest rates of overall survival (90.6%) and recurrence-free survival (97.0%), while the lowest overall survival rate was observed in those with the triple-negative subtype (81.3%) and the lowest recurrence-free survival rate was observed in those with the luminal B subtype (84.0%). Multivariate Cox proportional hazard analysis, using the luminal A subtype as the reference, revealed significant differences in recurrence-free survival among luminal B patients according to lymph node status. Among elderly Taiwanese women with breast cancer, the breast cancer subtype might help predict survival outcomes. The luminal B subtype was associated with poor recurrence-free survival, and lymph node status was useful for predicting recurrence-free survival in this subset of patients.

Introduction

The elderly population is increasing worldwide, and the proportion of Taiwanese women who are ≥65 years old is expected to increase from 14% in 2018 to 20% in 2025 [1]. Breast cancer is the most common cancer among women and the leading cause of cancer-related deaths worldwide [2]. The Taiwanese National Health Insurance database was used to estimate the annual prevalence and incidence of breast cancer between 1997 and 2013, which revealed a prevalence of 834.37 per 100,000 persons and an incidence of 93.00 per 100,000 persons in 2013.

In Taiwan, the standardized incidence was 52.34 per 100,000 person-year in 1997 and 93.00 per 100,000 person-year in 2013 [1, 3]. The age-standardized incidence rates (ASIR) have gradually increased over the past several years, with an incremental annual change of 3.5 per 100,000 persons. It suggests that the breast cancer incidence increased over the study period [2, 3]. Moreover, the fastest-growing population segment includes individuals who are ≥65 years old, and breast cancer is relatively common among women in this age group.

Recent advances in molecular testing have allowed breast cancers to be categorized into clinically relevant molecular subtypes. According to the St. Gallen International Breast Cancer Conference (2011), breast cancer subtypes (BCSs) are classified as luminal A, luminal B, luminal human epidermal growth factor receptor 2 (HER2), HER2, and triple negative (TN) [4-6]. Lymph node (LN) status is another factor that is strongly related to overall survival (OS) in breast cancer patients and has been an integral component in the staging, prognostication, and treatment of invasive breast cancers [6, 7]. Furthermore, recent data have indicated that the prognosis varies according to BCS [8]. However, the survival rates of elderly patients with breast cancer according to BCS and LN status have not been fully examined. Therefore, in this retrospective study, we evaluate and report the rates of OS and recurrence-free survival (RFS) among elderly Taiwanese breast cancer patients according to their BCS, as well as according to their LN status. To the best of our knowledge, this study includes the largest series of patients reported in the literature to date.

Materials and methods

Database

This retrospective study evaluated data from the electronic medical records of patients who were diagnosed with invasive breast cancer and underwent potentially curative surgery at the Tri-Service General Hospital (TSGH, Taipei, Taiwan) between June 2005 and June 2015. The information recorded for each patient included the age at diagnosis, year of diagnosis, and date of death or last contact. All patients had undergone either mastectomy or breast-conserving surgery, with subsequent endocrine therapy, local radiotherapy, or adjuvant systemic treatment, selected based on international recommendations [8-12]. We obtained follow-up data from the clinical history or over the phone. For deceased patients, the date and cause of death were also collected. The total incidences of recurrence or death due to breast cancer were determined based on follow-up visits that were conducted until October 2016. Living patients or patients without follow-up were censored at the end of the follow-up period. In our organization, all patients will be followed up for the first five years for six months and then once a year for the next five years. Follow-up examinations include physical examinations and blood tests to evaluate tumor markers, and it is recommended to have a bilateral mammogram (after lumpectomy) or the remaining contralateral breast (after mastectomy) for a follow-up examination every year. CT and MRI scans were not our routine follow-up inspection items. Tumor characteristics included tumor size (≤ 2, 2 to 5, and >5 cm); tumor pathologic stage (I, II, III, IV); status of ER, PR, and HER2 (positive, negative, or unknown); and LN status (negative or positive). Treatment factors included radiotherapy, type of surgery, chemotherapy, or endocrine therapy. The tumor pathologic stage was defined by the tumor node metastasis (TNM) classification as proposed by the American Joint Committee on Cancer (AJCC) for grouping patients with respect to prognosis.

Selection of the study subjects

According to the American Joint Cancer Council (AJCC) standards, the breast cancer database includes 4,363 newly diagnosed stage I, II, III, or IV patients in the Tri-Service General Hospital from 2005 to 2015. Exclude breast cancer patients< 65 years of age (n = 3,809). The exclusion conditions are as follow patients with other cancer diagnoses before or after the initial breast cancer diagnosis, patients lacking correct ER, PR, HER2 data or missing data, diseases with unknown surgical information or missing surgical data after the initial breast cancer diagnosis, lack of relevant information patients with tumor size or the number of positive axillary lymph nodes and patients who have never had a disease or whose recurrence date is missing or wrong. Finally, a total of 503 patients were eligible for analysis between age and clinicopathological characteristics including 203 luminal A breast cancer, 128 luminal B breast cancer, 88 luminal B2 breast cancer, 20 HER2+ breast cancer, and 32 TN breast cancer (Fig 1).

Fig 1

Flowchart presenting the process of selecting the study subjects.

The hospital started to promote the use of electronic medical records in 2001. The cancer center was formally established in 2002. Since then, the data of cancer patients began to be digitalized and registered year by year. At this time, electronic diseases are managed by using barcodes and radio frequency identification technology (radio frequency identification; RFID) to attach to the paper medical records, and then use database index and other technologies to record the location and flow of the paper medical records to achieve digitalization. From 2002 to 2009, our hospital adopted a mixed medical record model (paper medical records and electronic medical records exist at the same time). Because the legal status of electronic medical records has not been established and part of the electronic medical record system is not yet complete, our hospital adopts a transitional mixed medical record model. Between 2005 and 2009, we adopted large-scale manual methods to transfer paper medical records into electronic transcripts. At the same time, the construction of the electronic database of cancer patients in our hospital was completed from 2009 to 2010. Since then, the medical records of cancer patients have been all electronic.

The study’s retrospective protocol was reviewed and approved by the Tri-Service General Hospital’s human investigations committee (1-107-05-135). The requirement for informed consent was waived due to the retrospective nature of the study.

Tumor characteristics

Tumor-related data included those of LN status (negative or positive), tumor size (<2 cm, 2–5 cm, or >5 cm), and BCS. If data on the Ki-67 index were not available, some alternative measure of proliferation, such as the histological grade, was used to identify the BCS, as previously reported [6, 8, 13]. Intrinsic subtypes were classified into five groups based on immunohistochemistry findings: luminal A (estrogen receptor-positive [ER+] and/or progesterone receptor-positive [PR+], HER2−, and histological grade 1 or 2), luminal B (ER+ and/or PR+, HER2−, and histological grade 3), luminal B2 (ER+ and/or PR+, HER2+, and any histological grade), HER2+ (ER−, PR−, and HER2+), and TN (ER−, PR−, and HER2−). Immunohistochemistry was used to identify positively stained nuclei for determining ER/PR positivity (>1%). Tumors were considered HER2+ when the cells exhibited strong membrane staining (3+), and tumors were considered HER2– when they exhibited 0 or 1+ staining for HER2 protein expression. For patients with an equivocal membrane staining score for HER2 (2+), fluorescence in situ hybridization was performed to evaluate gene amplification [12, 14].

Statistical analysis

Continuous data are expressed as mean ± standard deviation, and categorical data are expressed as number (percentage). Survival intervals were calculated from the date of cancer diagnosis to the date of death because of any cause or the last follow-up (OS) or from the date of cancer diagnosis to the date of the first detected relapse or last follow-up without relapse (RFS). The chi-squared test was used to analyze categorical clinicopathological variables, and differences in OS and RFS according to BCS were analyzed using the Kaplan–Meier method and log-rank test. Multivariate Cox proportional hazard analysis was used to calculate adjusted mortality risks (hazard ratio [HR] and 95% confidence interval [CI]) and identify factors that best predicted OS and RFS. Differences were considered statistically significant at two-sided P-values <0.05. All statistical analyses were performed using IBM SPSS software (version 22.0; IBM Corp., Armonk, NY, USA).

Results

Clinicopathological characteristics

The distribution of BCSs among the 554 elderly Taiwanese women (>65 years old) was as follows: luminal A (46.7% of patients), luminal B (25.4% of patients), luminal B2 (17.5% of patients), HER2 (4.0% of patients), and TN (6.4% of patients) (Table 1). Significant differences were observed according to BCS in terms of tumor size (P < 0.001) and LN status (P = 0.001). Relative to the other subtypes, the luminal A subtype was the most likely to involve a smaller tumor size (49.4%) and the least likely to show LN involvement (31.5%). The HER2 subtype had the highest incidence of LN involvement (45.0%), while the TN subtype was the most likely to involve a large tumor size (28.1%). Most patients (88.9%) underwent surgery, which included breast-conserving surgery (12.3%) or modified radical mastectomy (76.6%). Other treatments included radiotherapy (24.4%), adjuvant chemotherapy (81.7%), and endocrine treatment (76.8%).

Table 1

Clinicopathological characteristics of all patients according to breast cancer subtype (age > 65, n = 503).

Variable	Luminal A (%)	Luminal B (%)	Luminal B2 (%)	HER2 (%)	TN (%)	P-value
Number of cases	235 (46.7)	128 (25.4)	88 (17.5)	20 (4.0)	32 (6.4)
Tumor size						<0.001*
≤2 cm	116 (49.4)	39 (30.5)	25 (28.4)	9 (45.0)	7 (21.9)
>2–5 cm	95 (40.4)	68 (53.1)	55 (62.5)	10 (50.0)	9 (28.1)
>5 cm	24 (10.2)	21 (16.4)	8 (9.1)	1 (5.0)	16 (50.0)
Lymph node status						0.001*
Negative	158 (79.4)	64 (61.0)	48 (62.3)	11 (55.0)	18 (64.3)
Positive	41 (31.5)	41 (39.0)	29 (37.7)	9 (45.0)	10 (35.7)
Operation type						0.335
No	27 (11.8)	17 (13.7)	7 (8.3)	0 (0.0)	3 (10.0)
Breast conservation surgery	30 (13.1)	12 (9.7)	10 (11.9)	1 (5.0)	7 (23.3)
Modified radical mastectomy	172 (75.1)	95 (76.6)	67 (79.8)	19 (95.0)	20 (66.7)
Radiotherapy						0.008*
No	188 (82.1)	87 (70.2)	63 (74.1)	14 (70.0)	17 (56.7)
Yes	41 (17.9)	37 (29.8)	22 (25.9)	6 (30.0)	13 (43.3)
Chemotherapy						0.008*
No	40 (18.6)	14 (11.8)	13 (16.7)	8 (40.0)	9 (34.6)
Yes	175 (81.4)	105 (88.2)	65 (83.3)	12 (60.0)	17 (65.4)
Endocrine therapy						<0.001*
No	25 (11.2)	15 (12.4)	23 (27.7)	20 (100.0)	28 (93.3)
Yes	199 (88.8)	106 (87.6)	60 (72.3)	0 (0.0)	2 (6.7)
Overall survival						0.185
Deceased	22 (9.4)	22 (17.2)	11 (12.5)	2 (10.0)	6 (18.8)
Alive	213 (90.6)	106 (82.8)	77 (87.5)	18 (90.0)	26 (81.3)
Recurrence-free survival						0.002*
Deceased	6 (3.0)	17 (16.0)	6 (8.1)	1 (6.3)	2 (6.7)
Alive	195 (97.0)	89 (84.0)	68 (91.9)	15 (93.7)	28 (93.3)

HER2, human epidermal growth factor receptor 2; TN, triple negative.

*Significant at P < 0.05.

Survival outcomes

Patients with the luminal A subtype had the highest 10-year rates of OS (90.6%) and RFS (97.0%). The lowest OS rate was observed for those with the TN subtype (81.3%), and the lowest RFS rate was observed for those with the luminal B subtype (84.0%) (Table 1). The Kaplan–Meier curves for OS and RFS according to the BCS are shown in Figs 2 and 3.

Fig 2

Kaplan–Meier curves of overall survival according to lymph node status and breast cancer subtype.

HER2, human epidermal growth factor receptor 2.

Fig 3

Kaplan–Meier curves of recurrence-free survival according to lymph node status and breast cancer subtype.

HER2, human epidermal growth factor receptor 2.

The difference in OS according to the BCS was not statistically significant (P = 0.135), although there was a significant difference in RFS according to the BCS (P = 0.002). In the multivariate Cox proportional hazard analysis, age of >65 years was independently associated with poor OS and RFS in the BCS subgroups after controlling for tumor size, LN status, radiotherapy, surgery type, chemotherapy, and hormone therapy (Table 2). Therefore, the luminal A subtype was used as the reference group, and we found that patients with the luminal B subtype had significantly poorer RFS (HR: 4.076, 95% CI: 1.426–11.649; P = 0.009), even after adjusting for tumor size, LN status, radiotherapy, surgery type, chemotherapy, and hormone therapy (Table 2). Furthermore, many investigators have reported a statistically significant association between the BCS and LN metastasis [6, 8, 9, 15, 16]. Therefore, we evaluated the OS and RFS according to the BCS and LN status (Table 3), which revealed a significant difference in RFS according to LN status among patients with the luminal B subtype (HR: 14.427, 95% CI: 1.409–147.740; P = 0.025).

Table 2

Multivariate analysis of overall and recurrence-free survival according to breast cancer subtype.

	Luminal A	Luminal B	Luminal B2	HER2	TN
	P-value and HR (95% CI)
Overall survival
	1(reference)	P = 0.1271.935(0.829–4.518)	P = 0.2801.702(0.648–4.469)	P = 0.8741.165(0.178–7.612)	P = 0.0983.883(0.777–19.398)
Recurrence-free survival
	1(reference)	P = 0.009*4.076(1.426–11.649)	P = 0.2992.028(0.534–5.951)	P = 0.5280.465(0.043–5.024)	P = 0.092.257(0.880–5.790)

HER2, human epidermal growth factor receptor 2; TN, triple negative; HR, hazard ratio; CI, confidence interval.

The model was adjusted for tumor size, lymph node status, radiotherapy, surgery type, chemotherapy, and hormone therapy.

*Significant at P < 0.05.

Table 3

Survival outcomes according to lymph node status and breast cancer subtype.

	Luminal A	Luminal B	Luminal B2	HER2	TN
P-value and HR (95% CI)
Overall survival
Lymph node status
Negative	1(reference)	P = 0.3861.671(0.523–5.338)	P = 0.7650.786(0.162–3.808)	P = 0.3055.307(0.219–128.530)	P = 0.9850.000(0.000–undefined)
Positive	1(reference)	P = 0.0814.328(0.834–22.471)	P = 0.0625.148(0.923–28.714)	P = 0.7080.602(0.042–8.613)	P = 0.0836.009(0.791–45.664)
Recurrence-free survival
Lymph node status
Negative	1(reference)	P = 0.0983.101(0.811–11.855)	P = 0.6891.429(0.248–8.231)	P = 0.9920.000(0.000–undefined)	P = 0.9880.000(0.000–undefined)
Positive	1(reference)	P = 0.025*14.427(1.409–147.740)	P = 0.0979.470(0.668–134.319)	P = 0.8050.694(0.038–12.578)	P = 0.8921.227(0.063–23.762)

HER2, human epidermal growth factor receptor 2; TN, triple negative; HR, hazard ratio; CI, confidence interval.

The model was adjusted for tumor size, radiotherapy, surgery type, chemotherapy, and hormone therapy.

*Significant at P < 0.05.

Discussion

Breast cancer is the second most common cancer worldwide and the most common cancer among women, with an estimated 1.67 million new cases diagnosed in 2012 (25% of all cancers) [2]. Furthermore, the elderly population is increasing worldwide, and breast cancer in elderly women is a major challenge for modern healthcare systems. Previous studies have indicated that advanced age is associated with more favorable tumor biology and that breast cancer-related survival in elderly women is similar to that in the general population, regardless of disease status [17]. For example, Kim et al. [18] compared 4388 patients with invasive breast cancer according to age (<65 and ≥65 years) and reported a median age of 47 years (range: 18–91 years) and 317 patients (7.2%) who were ≥65 years old. Their results indicated that the tumor characteristics were similar between the two age groups. Other investigators have demonstrated that the TN subtype is associated with a large tumor size [19-22], and Liao et al. [8] have reported that the highest risk of LN metastasis was observed for the luminal B and luminal B2 subtypes. The present study also revealed that the TN subtype was associated with a larger tumor size and that LN positivity was the most common among elderly breast cancer patients with the HER2 subtype. Interestingly, patients with the HER2 subtype were most likely to undergo modified radical mastectomy (95%).

While there was no significant difference in OS according to the BCS, we did detect a significant difference in RFS according to the BCS (luminal B vs. luminal A as the reference), even after adjusting for tumor size, LN status, radiotherapy, surgery type, chemotherapy, and hormone therapy. Garcia et al. [23] reported that patients with the luminal A subtype have the lowest prevalence of nodal involvement, as well as the lowest incidence of distant metastasis. Durbecq et al. [24] also reported that a significant proportion of patients aged >70 years develop luminal B-subtype tumors, which are associated with high proliferation, high grade, large size, and nodal invasion. We hypothesized that the luminal B subtype would involve higher grade tumors than would the other BCSs and accordingly compared the luminal A and B subtypes, which revealed significantly poorer RFS among elderly patients with the luminal B subtype and LN positivity. Lodi et al. [25] have reported that the differences in clinicopathological characteristics, increased incidence, and age-related mortality can be explained by biological changes in the breast, such as increased estrogen sensitivity, epithelial cell alterations, immune senescence, and tumor microenvironment modifications. However, these outcomes are also likely related to sociological factors, such as increased life expectancy, under-treatment, late diagnosis, and insufficient individual screening. The present study revealed similar results for survival outcomes, i.e., a significant difference in RFS according to the BCS, but only a non-significant difference in OS.

The present study has several potential limitations. For example, the study involved a retrospective analysis of data from a small sample of patients. However, to the best of our knowledge, this study included one of the largest series of patients reported in the literature to date. Thus, while previous studies have evaluated the association between LN status and individual BCSs, the prognostic value of the LN status and BCS has not been discussed for elderly breast cancer patients.

Conclusions

In conclusion, the present study revealed differences in OS and RFS according to the BCS among elderly Taiwanese patients with breast cancer. The luminal B subtype was associated with especially poor RFS, and LN status was useful for predicting RFS in this subset of patients. The findings from our study may provide clinicians with more references for determining the prognosis and treatment strategies for elderly women with varying BCSs and LN statuses. In the future, research on the optimal clinical treatments for elderly women with different BCSs, LN statuses, and genetic profiles should be conducted, with particular focus on the types with poor OS and RFS.

25 Aug 2021

PONE-D-21-21337

Survival outcomes in elderly Taiwanese women according to breast cancer subtype and lymph node status: a single-center retrospective study

PLOS ONE

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Reviewer #1: 1. What is the definition of the elderly in this study? The literature cited by the authors considers people 65 years of age or older as elderly.

2. How did the author screen out 554 cases? The inclusion and exclusion criteria should be specified in the Materials and Methods, and it is recommended to add a flow chart for subject screening.

3. The subjects in this study are patients from 2005 to 2015 and the data of these subjects are from electronic medical records. Has the electronic medical record been fully established for this period? If not, is there any way to make the data in this study as complete as possible? The authors should specify in the Materials and Methods.

4. Page 4, line 72: For "selected based on international recommendations", the authors should state clearly or cite relevant references.

5. Table 1: The total number of cases of all subtypes is 503, not 554.

6. Page 8, line 146-147: Some reference(s) should be cited for "many investigators have reported a statistically....and LN metastasis".

7. Page 8, line 149: According to the data in Table 3, "luminal HER2" should be corrected to "luminal B" here.

Reviewer #2: Question 1 - The use of person-years for incidence of breast cancer instead of an incidence rate in the Introduction is confusing. Also, a reference should be given for stat on the fastest-growing segment of the population.

It is unclear to me whether the use of immunohistochemistry used to identify ER/PR, HER2 status, etc. was done previously so the authors could access that data or if they performed the tests themselves on patient samples.

Question 3 - The authors state that the data cannot be shared publicly, but that it is available for certain researchers.

General comments - The numbers given for the number of HER2 positive patients as opposed to triple negative was surprising; there were more TN patients by several percentage points. Is this common in Taiwanese populations?

Table 1 comments - The tumor size was very large for 50% of the TN patients; it would be useful to know if this is because of late presentation. The numbers of modified radical mastectomies as opposed to breast conservation surgery are very high (which is surprising for elderly patients) but the least high for TN patients, unusual for the most aggressive form. Is this because the elderly patients did not want to undergo radiation after breast conserving surgery? It is not clear how much the patients' desires dictate treatment or what the standard of care is in Taiwan. There is no mention of specific HER2 therapy for HER2+ patients such as Herceptin or Trastuzumab; do the authors consider this chemotherapy and thus include it in the chemotherapy section or it is not available or not considered cost-effective for elderly patients in Taiwan? This needs to be clarified.

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1 Oct 2021

Dear Editor:

Thank you for inviting us to submit a revised draft of our manuscript entitled “ PLOS ONE Decision: Revision required [PONE-D-21-21337]” on Aug 25, 2021. We also appreciate the time and effort you and each of the reviewers have dedicated to providing insightful feedback on ways to strengthen our paper. Thus, it is with great pleasure that we resubmit our article for further consideration. We have incorporated changes that reflect the detailed suggestions you have graciously provided. We also hope that our edits and the responses we provide below satisfactorily address all the issues and concerns you and the reviewers have noted. We revised the manuscript following the reviewers’ comments and carefully proofread the manuscript to minimize typographical, grammatical, and bibliographical errors. Here below is our description of revision according to the reviewers’ comments.

To facilitate your review of our revisions, the following is a point-by-point response to the questions and comments delivered in your letter.

Part A

Reviewer #1:

1. The reviewer’s comment:

What is the definition of the elderly in this study? The literature cited by the authors considers people 65 years of age or older as elderly.

� The authors’ Answer:

In this study, the elderly is defined as 65 years of age or older. As the definition of old age is slightly different in different parts of the world, the current academic circles have no final conclusion on the specific age group of old age. The World Health Organization defines the elderly over 65 as the elderly. Despite growing research interest in the management of breast cancer in women over the age of 65, no internationally agreed recommendations exist for this population. The National Comprehensive Cancer Guidelines (NCCN) guidelines specifically define the elderly as patients over the age of 70 and recommend the use of elderly assessment tools for the elderly. The International Society of Geriatric Oncology (SIOG) guidelines define the elderly as patients over 65 years of age and provide evidence-based recommendations for the diagnosis and treatment of breast cancer in the elderly. In addition, if we study the definition of the elderly from 70 and 65 years old, the number of patients over 65 years old is indeed greater than the number of patients over 70 years old. In terms of studying various groups, it is easier to do research sample design

2. The reviewer’s comment:

How did the author screen out 503 cases? The inclusion and exclusion criteria should be specified in the Materials and Methods, and it is recommended to add a flow chart for subject screening.

� The authors’ Answer:

Thank you for your examination and suggestion. We have added inclusion and exclusion criteria to Materials and Methods, with the following additions: According to the American Joint Cancer Council (AJCC) standards, the breast cancer database includes 4,363 newly diagnosed stage I, II, III, or IV patients in the Tri-Service General Hospital from 2005 to 2015. Exclude breast cancer patients< 65 years of age (n=3,809). The exclusion conditions are as follow patients with other cancer diagnoses before or after the initial breast cancer diagnosis, patients lacking correct ER, PR, HER2 data or missing data, diseases with unknown surgical information or missing surgical data after the initial breast cancer diagnosis, lack of relevant information patients with tumor size or the number of positive axillary lymph nodes and patients who have never had a disease or whose recurrence date is missing or wrong. Finally, a total of 503 patients were eligible for analysis between age and clinicopathological characteristics including 203 luminal A breast cancer, 128 luminal B breast cancer, 88 luminal B2 breast cancer, 20 HER2+ breast cancer, and 32 TN breast cancer (Fig. 1).

LINE 110~122 PAGE 05~06

3. The reviewer’s comment:

The subjects in this study are patients from 2005 to 2015 and the data of these subjects are from electronic medical records. Has the electronic medical record been fully established for this period? If not, is there any way to make the data in this study as complete as possible? The authors should specify in the Materials and Methods.

� The authors’ Answer:

We agree with you and have incorporated this suggestion throughout our paper. We add the following content: The hospital started to promote the use of electronic medical records in 2001. The Cancer Registration Center was formally established in 2002. Since then, the data of cancer patients began to be digitalized and registered year by year. At this time, electronic diseases are managed by using barcodes and radio frequency identification technology (radio frequency identification; RFID) to attach to the paper medical records, and then use database index and other technologies to record the location and flow of the paper medical records to achieve digitalization—the purpose of medical record management. From 2002 to 2009, our hospital adopted a mixed medical record model (paper medical records and electronic medical records exist at the same time). Because the legal status of electronic medical records has not been established and part of the electronic medical record system is not yet complete, our hospital adopts a transitional mixed medical record model. Between 2005 and 2009, we adopted large-scale manual methods to transfer paper medical records into electronic transcripts. At the same time, the construction of the electronic database of cancer patients in our hospital was completed from 2009 to 2010. Since then, the medical records of cancer patients have been all electronic. At the same time, it has also completed the goal of digitizing the paper medical records of all cancer patients in our hospital in the past. LINE 124~138 PAGE 06

4. The reviewer’s comment:

Page 4, line 72: For "selected based on international recommendations", the authors should state clearly or cite relevant references.

� The authors’ Answer:

Thank you for your suggestion. The definition and classification of disease and treatment for breast cancer patients follow the international standards such as AJCC definitions, NCCN guidelines, and NICE guidelines. We have revised the cited references and attached the references. LINE 090~091 PAGE 04

5. The reviewer’s comment:

Table 1: The total number of cases of all subtypes is 503, not 554.

� The authors’ Answer:

Thank you for your examination. We have revised the wrong part of the article. LINE 190 PAGE 08

6. The reviewer’s comment:

Page 8, line 146-147: Some reference(s) should be cited for "many investigators have reported a statistically....and LN metastasis".

� The authors’ Answer:

Thank you for your examination. We have attached relevant references

LINE 216~217 PAGE 11

� Edge SB, Compton CC. The American Joint Committee on Cancer: the 7th edition of the AJCC cancer staging manual and the future of TNM. Annals of surgical oncology. 2010;17:1471-1474.

� Badwe R, Hawaldar R, Nair N, et al. Locoregional treatment versus no treatment of the primary tumour in metastatic breast cancer: an open-label randomised controlled trial. The Lancet. Oncology. 2015;16:1380-1388.

� Graham LJ, Shupe MP, Schneble EJ, et al. Current approaches and challenges in monitoring treatment responses in breast cancer. Journal of Cancer. 2014;5:58-68.

7. The reviewer’s comment:

Page 8, line 149: According to the data in Table 3, "luminal HER2" should be corrected to "luminal B" here.

� The authors’ Answer:

Thank you for your examination. We have revised the wrong part of the article. LINE 219 PAGE 11

Part B

Reviewer #2:

1. The reviewer’s comment:

The use of person-years for incidence of breast cancer instead of an incidence rate in the Introduction is confusing. Also, a reference should be given for stat on the fastest-growing segment of the population. It is unclear to me whether the use of immunohistochemistry used to identify ER/PR, HER2 status, etc. was done previously so the authors could access that data or if they performed the tests themselves on patient samples.

� The authors’ Answer:

Thanks for your comment. We rewrote relevant and difficult sentences. The rewritten paragraph is as follows: Breast cancer is the most common cancer among women and the leading cause of cancer-related deaths worldwide [2]. The Taiwanese National Health Insurance database was used to estimate the annual prevalence and incidence of breast cancer between 1997 and 2013, which revealed a prevalence of 834.37 per 100,000 persons and an incidence of 93.00 per 100,000 persons in 2013. In Taiwan, the standardized incidence was 52.34 per 100,000 person-year in 1997 and 93.00 per 100,000 person-year in 2013 [1,3]. The age-standardized incidence rates (ASIR) have gradually increased over the past several years, with an incremental annual change of 3.5 per 100,000 persons. It suggests that the breast cancer incidence increased over the study period [2,3]. In addition, we have previously tested patient samples and used immunohistochemistry to identify ER/PR, HER2 status, etc., to study the data. So this time, we will not repeat it.

LANE41~50 PAGE 3

2. The reviewer’s comment:

The numbers given for the number of HER2 positive patients as opposed to triple negative was surprising; there were more TN patients by several percentage points. Is this common in Taiwanese populations?

� The authors’ Answer:

To avoid readers' misunderstanding, we have changed Luminal HER2 to Luminal B2 to make it easier to understand. The distribution of BCSs among the 554 elderly Taiwanese women (>65 years old) was as follows: luminal A (46.7% of patients), luminal B (25.4% of patients), Luminal B2 (17.5% of patients), HER2 (4.0% of patients), and TN (6.4% of patients). There are indeed slightly more patients in the TN group than in the HER2 group. The reason is that some patients lost contact or refused to cooperate during the long-term follow-up of the patients and withdrew from the study. We have deducted the in complete part of the data, so the data numbers make the TN group look slightly more significant. However, the two groups of Luminal B2 and HER2 patients together account for approximately 21.5%. According to research published in the past, the proportions of luminal-A, luminal-B, HER2-positive, and triple-negative subtype are 50%~60%, 15%~20%, 15~20%, 8%~37%, respectively. Therefore, if we add up the number of Luminal B2 patients and the number of HER2 patients in our study, 108 (21.5%) are in line with the digital content reported in the previously published papers. From the data in the past few years, the number of HER2-positive patients is indeed on the rise. In the past few years, there were more than 10,000 new patients in Taiwan each year, of which a quarter was HER2-positive. It is estimated that there will be an increase of 3,000 HER2-positive breast cancer patients in Taiwan each year. In addition, a 2009 study by Lin CH et al. pointed out that the prevalence of breast cancer in Taiwanese elderly (>50 years old) breast cancer patients are higher than that of young people (≤50 years old) breast cancer patients with basal-like subtypes (17% vs. 9%)

3. The reviewer’s comment:

Question 3-Table 1 comments - The tumor size was very large for 50% of the TN patients; it would be useful to know if this is because of late presentation. The numbers of modified radical mastectomies as opposed to breast conservation surgery are very high (which is surprising for elderly patients) but the least high for TN patients, unusual for the most aggressive form. Is this because the elderly patients did not want to undergo radiation after breast conserving surgery? It is not clear how much the patients' desires dictate treatment or what the standard of care is in Taiwan. There is no mention of specific HER2 therapy for HER2+ patients such as Herceptin or Trastuzumab; do the authors consider this chemotherapy and thus include it in the chemotherapy section or it is not available or not considered cost-effective for elderly patients in Taiwan? This needs to be clarified.

� The authors’ Answer:

I. The tumor size for the TN patients of breast cancer in this study is indeed relatively large, but this is the result of our research and statistical analysis. The reason is speculated that it may be related to the lack of screening concepts of patients in the past, the insufficient popularization of suitable screening equipment, and patients' delay in seeking medical treatment.

II. In this study, the proportion of TN patients undergoing MRM surgery is relatively large. We speculate that the reason may be that if elderly breast cancer patients decide to receive treatment, the patient pays more attention to their own health than breast beauty and breast functionality. As far as the local people in Taiwan are concerned, elderly breast cancer patients believe that they will be healthier and less likely to relapse after undergoing MRM surgery. It is not because elderly patients do not want to receive radiotherapy after breast-conserving surgery.

III. Our standards for treating breast cancer patients are based on our hospital’s breast cancer treatment guideline, which is modified majority by the direction of the National Comprehensive Cancer Network (NCCN) guidelines and the National Institute for Health and Clinical Excellence (NICE) guidelines. For the current hormone therapy for specific HER2 therapy for HER2+ patients, we will first assess whether the patient's heart's left ventricular ejection fraction (LVEF) is normal, and the patient's LN positive can be administered. For elderly breast cancer patients in Taiwan, Herceptin is available and considered cost-effective. However, the cost of Herceptin drugs is too expensive for patients. Herceptin was not officially included in Taiwan's National Health Insurance until January 1, 2010. Prior to this, patients with breast cancer in Taiwan must use Herceptin at their own expense. Most patients cannot afford expensive drugs at their own expense, so most patients gave up Herceptin treatment before 2010. In addition, targeted therapy (Herceptin or Trastuzumab) generally requires combined chemotherapy to treat breast cancer effectively. Here, the chemotherapy used is paclitaxel (PTX). In addition, we will arrange surgery for patients with early TN breast cancer. On the contrary, we will not arrange surgery for patients with metastatic TN breast cancer.

IV. According to the study of Kuo CN et al. in 2020, breast cancer treatment in Taiwan is currently as follows: The treatment of early-stage breast cancer is comprehensively determined by tumor size, nodal status, and expression of ER, PR, and human epidermal growth factor receptor-2 (HER2). For surgically resected hormone-receptor-positive breast cancer, adjuvant hormonal therapy is always indicated. Five-year treatment of tamoxifen plus exemestane or 5-year tamoxifen following 5-year letrozole are options for postmenopausal women, while ovarian suppression therapy plus tamoxifen is an alternative to chemotherapy for the selected premenopausal woman. In HER2-positive patients, one-year adjuvant trastuzumab has been approved for the node-positive disease. In addition to anthracycline, paclitaxel or docetaxel is generally the primary therapy offered to patients with node-positive cancer. In patients with metastatic disease, tamoxifen, letrozole, anastrozole, and exemestane are the treatment of choice for hormone-positive breast cancer. For letrozole-failed hormone-receptor-positive disease, everolimus plus exemestane is a viable treatment option. (After Dec. 2019, CDK46i was approved by our national health insurance for HR+ mBC). Trastuzumab-based treatment is an option for breast cancer with overexpression of HER2.

-------------------------------------------------------------------------------------------------------

CONCLUDING REMARKS:

Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries. We have worked hard to incorporate your feedback and hope that these revisions persuade you to accept our submission. Many grammatical or typographical errors have been revised. All the lines and pages indicated above are in the revised manuscript. We acknowledge the reviewer’s comments and suggestions very much, which are valuable in improving the quality of our manuscript. Thank you and all the reviewers for the kind advice.

Sincerely yours,

Guo-Shiou Liao, MD.

Corresponding Author

Division of General Surgery, Department of Surgery,

Tri-Services General Hospital, National Defense Medical Center,

No 325, Sec. 2, Cheng-Kung Rd, Nei-Hu 114, Taipei, Taiwan, R.O.C.

Tel: +886-2-87927191;Fax: +886-2-87927273

E-mail: guoshiou@ndmctsgh.edu.tw

Submitted filename: Response to PlosOne reviewers 20211002.docx

Click here for additional data file.

29 Nov 2021

Survival outcomes in elderly Taiwanese women according to breast cancer subtype and lymph node status: a single-center retrospective study

PONE-D-21-21337R1

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Additional Editor Comments (optional):

All the issues were answered adequately.

Reviewers' comments:

13 Dec 2021

PONE-D-21-21337R1

Survival outcomes in elderly Taiwanese women according to breast cancer subtype and lymph node status: a single-center retrospective study

Dear Dr. Liao:

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