Abstract P2-14-06: Systemic therapy for and prognosis of older stage II and III breast cancer patients: Evaluation of data from the Japanese breast cancer registry
Authors: Yamada Akimitsu , Sawaki Masataka , Kumamaru Hiraku , Miyata Hiroaki , Nakayama Kanako , Shimizu Chikako , Miyashita Mika , Honma Naoko , Endo Itaru , Taira Naruto , Saji Shigehira 
Published: March 2020

Abstract
Background: Currently, treatment for older breast cancer patients is largely based on data derived from trials enrolling younger patients; thus, the standard of care for older breast cancer patients remains controversial.
Aim: To investigate the clinicopathological characteristics, treatments, and prognosis in older stage II and III breast cancer patients using data from the Japanese Breast Cancer Registry (JBCR).
Methods: We reviewed data from the JBCR, a nationwide registry of newly diagnosed and operated primary breast cancer patients in Japan. To clarify those characteristics, we compared clinicopathological characteristics, treatments, and prognosis among three groups: older group, patients aged ≥75 years; young-old group, patients aged 65–74 years; post-menopause group, patients aged 55–64 years.
Results: In total, we reviewed 56,093 cases of stage II/III breast cancer diagnosed between 2004 and 2011 (older: n=12,727; young-old: n=17,860; post-menopause: n=25,506). The estrogen receptor (ER) positivity rate was higher (older vs. young-old vs. post-menopause: 73.3% vs. 72.0% vs. 68.0%) and HER2 positivity rate was lower in the older group than in the other two groups (12.9% vs. 16.8% vs. 23.6%) (p&lt;0.001).
The following table shows the rate of administration of adjuvant systemic therapy according to the ER and HER2 status.
Age (years)≥7565–7455–64p-valueER+Chemotherapy10.042.562.9&lt;0.001Endocrinetherapy83.788.887.7&lt;0.001ER-Chemotherapy33.576.787.7&lt;0.001HER2+Chemotherapy27.474.386.3&lt;0.001Trastuzumab31.659.162.7&lt;0.001
Nearly half of the older patients (48.3%) who received chemotherapy received either cyclophosphamide-methotrexate-fluorouracil or oral fluorouracil. As for hormone therapy, tamoxifen was used more frequently in the older group than in the young-old and post-menopause groups (16.5% vs. 8.6% vs. 7.2%).
The following table shows the results of the 5-year overall survival (OS) and breast cancer-specific survival (BCSS) analyses:
Conclusions: Chemotherapy was less common in older patients, especially patients with HER2+ or triple negative breast cancer, resulting in worse BCSS. As older patients tend to have several comorbidities, comprehensive geriatric assessment might be helpful in determining systemic therapies for older patients.
Age (years)≥7565–7455–64p-valueER+OS/BCSS (%)84.1/94.592.5/96.093.2/94.9&lt;0.001/&lt;0.001HER2+OS/BCSS (%)75.7/87.190.6/93.991.6/93.2&lt;0.001/&lt;0.001Triple negativeOS/BCSS (%)64.9/78.681.8/86.382.6/85.3&lt;0.001/&lt;0.001
Citation Format: Akimitsu Yamada, Masataka Sawaki, Hiraku Kumamaru, Hiroaki Miyata, Kanako Nakayama, Chikako Shimizu, Mika Miyashita, Naoko Honma, Itaru Endo, Naruto Taira, Shigehira Saji. Systemic therapy for and prognosis of older stage II and III breast cancer patients: Evaluation of data from the Japanese breast cancer registry [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-06.