Surgical outcome of combined subsegmentectomy in the right upper lobe for GGO -dominant early stage lung cancer: Analysis of 7 cases.

Combined subsegmentectomy (CSS) is procedure as diagnostic purpose adding sufficient surgical margin. Compared to other procedure, CSS is not common, with the surgical results also being controversial. We analyzed the patients who had undergoing CSS in the right upper lobe for ground glass opacity (GGO) -dominant nodules. Between April 2011 and March 2017, we experienced 7 cases underwent CSS. In all cases, three subsegments resection and lymph node dissection using Video-Assisted Thoracic Surgery (VATS) was performed. The mean radiological tumor size was 1.4 (1.1-1.9) cm and the mean consolidation/tumor ratios was 19 (0-33) %. Pathological diagnosis was all t1a-pIA1 adenocarcinoma in all cases, curative resection was obtained with sufficient margin. There were no serious postoperative complications or death within 90 days after treatment. Unfortunately, one patient died of pneumonia 28 months after surgery, but there was no recurrence and other delayed adverse events (follow up period was mean 42.8 months). We conclude that CSS had effects on both tumor control and preservation of the residual lungs with tolerable complications.

Introduction

In recent years, advances in the imaging examination have revealed the small pulmonary lesions and led to the accurate detection of early stage lung cancer [1]. If the preoperative histological diagnosis of lung cancer is confirmed, standard lobectomy and node dissection is indicated, and if not confirmed, diagnostic lung resection will be performed. Such lesions often require anatomical lung resection for some reason (not palpable, near the central region of the thorax or close to the pulmonary vessels, etc.), which is a further dilemma for surgeons. Also, we have felt as a clinical problem in especially right upper lobe from before. Therefore, we have performed combined subsegmentectomy (CSS) for central small pulmonary lesion which was suspected lung cancer as a diagnostic purpose adding sufficient surgical margin.

CSS, which resects the segment with the adjacent subsegment may be able to guarantee both preservation of residual lung and therapeutic effect by keeping surgical margin. Compared to other anatomical lung resection procedure, this complicated procedure has few reports. In this time, we retrospectively reviewed our 7 patients underwent right upper lobe CSS and analyzed their clinical outcomes.

Case presentation

Between April 2011 and March 2017, we experienced seven right upper lobe CSS (Table 1). The median age was 67 years (range, 53–85), and there was only one male. Patients condition including performance status was generally good. 2 patients with accompanying respiratory disease were well managed with inhaled medicine. Spirometry abnormalities included 2 patients, with 1 having a vital capacity (VC) of less than 80% and 1 with a forced expiratory volume in 1 s (FEV1)/functional vital capacity (FVC) of less than 70% (patient had emphysema).

Table 1

Clinical characteristics of the patients.

Variables	Results
Gender (n)
Male	1
Female	6
Age, years	67 (53–85)
Performance Status (n)
0	6
≧1	0
Smoking history	2
Respiratory comorbidity (n)
COPD	1
Asthma	1
Spirometry test
VC (L)	2.19 ± 0.50
%VC	86.3 ± 10.8
FEV1 (L)	1.62 ± 0.34
FEV1/FVC	84.6 ± 9.2

VC: vital capacity, FEV1: forced expiratory volume in 1 s, FVC: functional vital capacity.

Chest computed tomography (CT) revealed ground glass opacity (GGO) -dominant nodules, that were located near the central region of the lung where wedge resection was supposed to be difficult, in all cases (Fig. 1). The mean tumor diameter was 1.4 (1.1–1.9) cm and the mean CTRs (consolidation/tumor ratios) was 19 (0–33) % (Table 2). In all cases, the preoperative diagnosis was not confirmed and underwent CSS for diagnostic purpose and expectation of treatment (see Fig. 2).

Fig. 1

The radiological finding of Case No.7. Chest computed tomography (CT) revealed a ground glass opacity-dominant nodule located in the right upper lobe (S1a).

Table 2

Clinicopathologic details and postoperative outcomes.

Case No. (age, sex)	B.I.	main location of tumor	Radiological size (cm)		Surgical approach	Resected location	Pathological diagnosis	Recurrence	Prognosis
			Total	solid
1 (67, F)	0	S1a	1.5	0.5	VATS	S1+S2a	t1a-pIA1, pl0, G1, ly0, v0, adeno	No	72 mo, alive
2 (71, F)	250	S2a	1.4	0	VATS	S1a+S2	t1a-pIA1, pl0, G1, ly0, v0, adeno	No	60 mo, alive
3 (53, F)	0	S2b	1.1	0.2	VATS	S1a+S2	t1a-pIA1, pl0, G1, ly0, v0, adeno	No	60 mo, alive
4 (64, F)	0	S1a	1.8	0.5	VATS	S1+S2a	t1a-pIA1, pl0, G1, ly1, v0, adeno	No	28 mo, deada
5 (85, M)	1800	S2b	1.9	0.3	VATS	S2+S3a	t1a-pIA1, pl0, G1, ly0, v0, adeno	No	32 mo, alive
6 (67, F)	0	S2b	1.3	0.2	VATS	S2+S3a	t1a-pIA1, pl0, G1, ly0, v0, adeno	No	26 mo, alive
7 (53, F)	0	S1a	1.2	0.3	VATS	S1+S2a	t1a-pIA1, pl0, G1, ly0, v0, adeno	No	18 mo, alive

VATS: video-assisted thoracoscopic surgery.

Due to pneumonitis.

Fig. 2

Intraoperative findings of Case No.7. Intraoperative findings showing that blood vessels and bronchi belonging to S1 were cut and separated. B2a was secured by silk thread, and this patient underwent combined subsegmentectomy (CSS), resecting S1+S2a.

In all cases, three subsegments resection and lymph node dissection (ND1b) using Video-Assisted Thoracic Surgery (VATS) was performed (Table 2). The mean operation time and blood-loss were 310 (258–389) mins and 106 (25–202) g. There was no case required conversion to thoracotomy (open surgery) or transfusion therapy. All patients underwent curative resection (R0) with surgical margin equal to or greater than tumor diameter. Chest drain removal was done on mean 3 (1–5) day after surgery, and there was no case of prolonged air leak. No postoperative complication beyond grade 3 classified by Clavien-Dingo classification.

The pathological finding was shown in Table 2. Classified by TNM 8th edition, pathological diagnosis was t1a-pIA adenocarcinoma in all cases. Postoperative observation period was mean 42.8 (18–72) months. During the follow-up, all patients was free from neither local nor distant recurrence. Unfortunately, one patient died of pneumonia, but not shown tumor recurrence.

Discussion

Segmentectomy is often adapted for undiagnosed small pulmonary lesion as diagnostic purpose. For lung cancer, several studies have reported [[2], [3], [4], [5], [6]], been adapted as limited lung resection. Excluding the right middle lobe, segmentectomy in the left upper lobe and both lower lobes has been standardized, but in the right upper right lobe it is cumbersome due to its anatomical complexity. Also, due to the number of segments is small, lobectomy is often adapted for diagnosis, so much discussion about the significance of CSS had not been made. We believe that our study leads advanced knowledge by revealing unresolved issues pertaining to CSS.

Subsegmentectomy and CSS are not common procedure compared to segmentectomy, and there has been few previous reports. In our study, patients were recurrence-free including local recurrence during the follow-up. Survival time was also acceptable. Because they had not received adjuvant therapy, the treatment effect seems to be from surgery alone. Although GGO-dominant tumors with low CTRs are known as non-aggressive lung adenocarcinomas [7,8], Suzuki et al. reported that even if the tumors had low CTRs, there was still a possibility of cases with the presence of pathological-invasive components [9]. In our population, the maximum CTRs was 0.33. But one patient with lower CTRs had pathological invasive component (Case No. 4). Therefore, 3 subsegments resected with CSS may be an adequate volume to obtain cure for smaller than 2 cm and N0 stage tumors.

To identify accurate segmental and subsegmental division, we used the air-collapse line or/and a fluorescence imaging video system with indocyanine green (ICG), besides vessel travel as guidance. Although theses technique slightly affected the operation time extension, it seems that it brought about the effect of avoiding local recurrence any more.

Another argument is the influence on residual lung. CSS procedure required more surgical attention to smaller structures, and operation time tended to prolong a little. On the other hand, there was not much intraoperative bleeding, and it was possible to perform surgery safety by VATS approach. Postoperative complications involving invasive treatment was also none. Prolonged air leakage is often a problem after sublobar resections [10], there were no patients in which air leakage was prolonged or relapsed after drain removal.

It is also important that there is no decrease in lung volume due to atelectasis or bronchial stenosis. If there was a lack of blood flow or ventilation, residual lungs should had been affected by organizing and roughening. In fact, such findings were not seen in postoperative CT. With the except for one patient, no postoperative delayed adverse events occurred. In other words, CSS, resecting 3 subsegments could have maintained good ventilation-blood flow redistribution for residual lungs. Although routine spirometry was necessary for detailed evaluation, it could not be performed in all patients. We think it as a future task.

In conclusion, we found CSS which is a complicated procedure that has few reports in the literature led to be acceptable result for early stage lung adenocarcinoma. In the right upper lobe, 3 subsegments resection was balanced to guarantee preservation of the residual lungs.

Conflicts of interest

Conflict of interest statement: the authors have no competing interests.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.