e12511 Background: Standard adjuvant therapy for HER2 positive female breast cancer patients that are estrogen receptor (ER) positive is chemotherapy, trastuzumab, and endocrine therapy. For patients older than 70 years of age, the combination of chemotherapy and trastuzumab may increase the toxicity profile. The purpose of this study was to evaluate the role of chemotherapy in for the ER+/PR+/HER- and ER+/PR+/HER+ subtypes in patients over age 70. These subtypes differ only by HER2 status. Methods: We identified 13,167 cases of patients over age 70 with stages 1-3 first primary invasive breast cancer from the California Cancer Registry diagnosed between January 1, 2000 and December 31, 2010. Of these, 9,710 were ER+/PR+/HER- and 988 were ER+/PR+/HER+. Cox regression analysis adjusted for race/ethnicity, socioeconomic status, grade, and year of diagnosis was used to compare risk of mortality for combination endocrine and chemotherapy versus endocrine therapy alone. Analyses were conducted separately for each stage. Results: For the ER+/PR+/HER- subtype, there was no difference in the risk of mortality for patients given endocrine and chemotherapy versus endocrine therapy alone for stages 1 and 2. For stage 3, there was a 57% reduced risk of mortality (HR = 0.43; 95%CI: 0.27-0.69) for patients given combination chemo and endocrine therapy. For the ER+/PR+/HER+ subtype, there were no differences in risk of mortality in any stage due to treatment. Conclusions: With the exception of stage 3 patients with the ER+/PR+/HER- subtype, chemotherapy appears to add little or no benefit to risk of mortality for patients over 70 years of age. These results support the use of endocrine therapy and anti-HER2 therapy without chemotherapy in elderly patients with early stage, estrogen receptor positive, HER2 positive breast cancer.
52P Adjuvant endocrine therapy in HER2-positive breast cancer patients: Systematic review and meta-analysis
