Abstract 2761: Adjuvant chemotherapy outcomes of node negative, T1a,T1b,T1c hormone receptor-negative HER2-positive breast cancer patients

Background: Patients (pts) with early stage HER2neu-positive breast cancers have a higher risk of recurrence and death compared to hormone receptor positive patients. NCCN guidelines recommends adjuvant chemotherapy for Stage II and above HER2-positive breast cancer patients. It is unclear what benefit patients with Stage I HER2-positive breast cancer receive from adjuvant chemotherapy. The current study evaluates the effects of adjuvant chemotherapy on the survival of early stage ER/PR negative, HER2-positive breast cancer patients registered to the National Cancer Data base (NCDB) from 2010-2012. Patients and Methods: 3416 women from the NCDB were identified with Stage I ER, PR negative, HER2-positive breast cancer diagnosed between 2010-2012. The primary measured outcome was overall survival. Pts were grouped by tumor size (T1a,T1b,T1c) and adjuvant chemotherapy or no adjuvant chemotherapy. Additionally, patients were also grouped into lumpectomy with radiation and mastectomy with or without radiation. Adjusted variables included age, race, Charlson Comorbidity Index (CCI), payer status, income, education, distance travelled, diagnosing/treating facility and treatment delay. Multivariate Cox regression was used to investigate the effect of adjuvant chemotherapy on overall survival while adjusting for other factors. Results: There were a total of 3416 patients, mean age at diagnosis of 57.9 (range 22-90). The mean age was 56.2 years for the chemotherapy group and 61.8 for the no chemotherapy group. Pathological stage distribution was T1a (24.9%), T1b (24.7%) and T1c (50.2%). Adjuvant chemotherapy was received by 49.5% of T1a, 83.5% of T1b and 95% of T1c pts. Mean patient follow up was 2.7 years (range 0.05-5 years) In univariate analysis, the hazard ratio (HR) of death for chemotherapy vs no chemotherapy in each T stage was: T1a; 1.22 (0.46-3.28), T1b; 0.221 (0.095-0.512), T1c; 0.217 (0.094-0.498). In multivariate analysis, adjusting for other factors in the model, HR of death was 0.51 (95%CI: 0.26-1.03) for chemotherapy vs no chemotherapy. The HR of death was 1.92 (95%CI: 1.11-3.32) for pts who received mastectomy without radiation compared to lumpectomy with radiation. In addition, we observed a HR of 5.16 for CCI score of 2 or above as compared to score of 0. There was no difference in outcome based on payer status or race. Conclusion: Patients with early stage T1 a-c HER2-positive breast cancer had a marginal improvement in overall survival with the addition of chemotherapy. Patients who underwent lumpectomy with radiation were also found to have better overall survival compared to mastectomy without radiation. However, the relatively short follow up and the lack of cancer recurrence information preclude making definitive conclusions relative to adjuvant therapy for pts with these tumors. Longer follow-up and prospective controlled trials will be needed to quantify these potential benefits. Citation Format: Anu Paul, Runhua Shi, Prakash Peddi, Gary Burton. Adjuvant chemotherapy outcomes of node negative, T1a,T1b,T1c hormone receptor-negative HER2-positive breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2761. doi:10.1158/1538-7445.AM2017-2761