Soo Jin Park1, Moo Hyun Lee2, Sun-Young Kong3,4, Mi Kyung Song5, Jungnam Joo5, Youngmee Kwon1, Eun-Gyeong Lee1, Jai Hong Han1, Sung Hoon Sim1, So-Youn Jung1, Seeyoun Lee1, Keun Seok Lee1, In Hae Park6, Eun Sook Lee7,8. 1. Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do, Goyang, 10408, Republic of Korea. 2. Department of Surgery, Keimyung University School of Medicine, Daegu, Republic of Korea. 3. Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Republic of Korea. 4. Department of Laboratory Medicine & Genetic Counselling Clinics, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea. 5. Biometrics Research Branch, Division of Cancer Epidemiology and Management, Research Institute, National Cancer Center, Goyang, Republic of Korea. 6. Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do, Goyang, 10408, Republic of Korea. parkih@ncc.re.kr. 7. Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do, Goyang, 10408, Republic of Korea. eslee@ncc.re.kr. 8. Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Republic of Korea. eslee@ncc.re.kr.
Abstract
PURPOSE: We assessed the use of chemotherapy in breast cancer patients to investigate the factors that changed trends in chemotherapy following the adoption of the 21-gene expression assay in tumor genomic profiling. METHODS: Our study used 2033 patients from the National Cancer Center in Korea diagnosed with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer (tumor size of 0.5 cm or larger and 0-3 node metastases) from 2010 to 2015. We analyzed use of the 21-gene expression assay, changes in frequency of adjuvant chemotherapy use, and clinicopathological factors related to adjuvant chemotherapy to assess the impact of the 21-gene expression assay. RESULTS: Adjuvant chemotherapy use declined from 33.33% (2011) to 13.59% (2015) [relative risk (RR), 0.71; 95% CI 0.56-0.89; ptrend = 0.004] in patients with 21-gene expression assay data. Among patients without assay data, adjuvant chemotherapy use decreased from 76.79 to 40.17% between 2010 and 2015 (RR 0.87; 95% CI 0.84-0.91; ptrend < 0.001), especially for patients with node-negative/micrometastasis (RR 0.85; 95% CI 0.81-0.89; ptrend < 0.001). The frequency of adjuvant chemotherapy was significantly decreased after introduction of the 21-gene expression assay (p < 0.001). Tumor size (p < 0.001), progesterone receptor (PgR) status (p = 0.001), and proliferation index (Ki-67) levels (p < 0.001) were important factors for chemotherapy decision-making in node-negative/micrometastasis patients who did not undergo the assay. CONCLUSIONS: For HR-positive, HER2-negative breast cancer patients with 0-1 node metastases, chemotherapy use declined significantly after the adoption of the 21-gene assay. PgR status and Ki-67 were useful for chemotherapy decision-making in cases without the 21-gene assay.
PURPOSE: We assessed the use of chemotherapy in breast cancerpatients to investigate the factors that changed trends in chemotherapy following the adoption of the 21-gene expression assay in tumor genomic profiling. METHODS: Our study used 2033 patients from the National Cancer Center in Korea diagnosed with hormone receptor (HR)-positive, humanepidermal growth factor receptor 2 (HER2)-negative breast cancer (tumor size of 0.5 cm or larger and 0-3 node metastases) from 2010 to 2015. We analyzed use of the 21-gene expression assay, changes in frequency of adjuvant chemotherapy use, and clinicopathological factors related to adjuvant chemotherapy to assess the impact of the 21-gene expression assay. RESULTS: Adjuvant chemotherapy use declined from 33.33% (2011) to 13.59% (2015) [relative risk (RR), 0.71; 95% CI 0.56-0.89; ptrend = 0.004] in patients with 21-gene expression assay data. Among patients without assay data, adjuvant chemotherapy use decreased from 76.79 to 40.17% between 2010 and 2015 (RR 0.87; 95% CI 0.84-0.91; ptrend < 0.001), especially for patients with node-negative/micrometastasis (RR 0.85; 95% CI 0.81-0.89; ptrend < 0.001). The frequency of adjuvant chemotherapy was significantly decreased after introduction of the 21-gene expression assay (p < 0.001). Tumor size (p < 0.001), progesterone receptor (PgR) status (p = 0.001), and proliferation index (Ki-67) levels (p < 0.001) were important factors for chemotherapy decision-making in node-negative/micrometastasis patients who did not undergo the assay. CONCLUSIONS: For HR-positive, HER2-negative breast cancerpatients with 0-1 node metastases, chemotherapy use declined significantly after the adoption of the 21-gene assay. PgR status and Ki-67 were useful for chemotherapy decision-making in cases without the 21-gene assay.