Factors Influencing Adjuvant Chemotherapy and Trastuzumab Choice in Older Human Epidermal Growth Factor Receptor 2-positive Breast Cancer Patients

Objectives: This study aims to evaluate influence factors for adjuvant chemotherapy regimen choice on the basis of trastuzumab in older human epidermal growth factor receptor 2 (HER2)-positive breast cancer under multi-disciplinary team (MDT) modality. Materials and Methods: HER2-positive breast cancer patients aged ≥ 60 years who received breast cancer surgery between April 2013 and December 2017 in Shanghai Ruijin Hospital were retrospectively enrolled. Clinical and pathological features, MDT recommendations, administration of adjuvant treatment, cardiotoxicity, and disease outcome information were reviewed and analyzed. Results: A total of 222 older HER2-positive breast cancer patients were included and recommended to receive adjuvant chemotherapy plus trastuzumab therapy. Paclitaxel plus trastuzumab (PH, 41/222, 18.5%), docetaxel plus carboplatin and trastuzumab (TCH, 62/222, 27.9%), and antharcyclines plus cyclophosphamide followed by taxanes and trastuzumab (AC-TH, 119/222, 53.6%) were the three main regimens. Patients with T1a-b (P<0.001), grade 1-2 (P=0.008), node-negative (P<0.001), stage I (P<0.001), low Ki-67 level (P<0.001) disease, with cardiovascular comorbidities (P=0.011), and aged ≥ 70 years (P<0.001) were more likely to be recommended to PH regimen. Among the 178 patients who finally received adjuvant chemotherapy plus one-year trastuzumab treatment, only four patients (4/117, 3.4%) were recorded to have asymptomatic LVEF declining ≥ 10% but remaining ≥ 50% within one-year trastuzumab treatment. Conclusions: Clinical factors, including age, tumor size, node status, and cardiovascular comorbidity influenced the recommendation of trastuzumab with chemotherapy for older HER2-positive breast cancer patients. Low risk older HER2-positive breast cancer patients treated with PH had favorable outcome and good cardiac safety, which needed further clinical validation.