1521 Background: Aspirin or NSAID (A/N) use post diagnosis is associated with lower risk of breast cancer recurrence and mortality in cohort studies. A potential mechanism is that A/Ns may suppress cell growth and induce apoptosis in tumors driven by phosphatidylinositol 3 kinase ( PIK3CA), the most common oncogene mutation in breast cancer. An interaction of A/Ns and PIK3CA mutation has been observed for colorectal cancer prognosis, but has not been studied in breast cancer. The objective was to assess time to breast cancer recurrence (TTR) with respect to A/N use and PIK3CAmutation. Methods: Patients with HR+/HER2- breast cancer treated at Massachusetts General Hospital in 2009-2014 who received tumor genotyping were included. PIK3CA mutations, including 8 common hotspot mutations, were assessed by a high-throughput tumor genotyping assay using DNA from formalin-fixed, paraffin-embedded tumor tissue. A/N use beginning 6 months post diagnosis through metastasis was extracted from electronic medical records using coded data and natural language processing. Patients with de novo metastatic disease or progressive disease within 6 months of primary diagnosis were excluded. TTR was estimated using Cox proportional hazards models. Results: Among breast cancer patients (N=212), 60 (28%) used A/Ns and 69 (33%) had PIK3CA mutation (see Table). After adjusting for age, stage, adjuvant endocrine therapy, radiation, and chemotherapy, A/N users had significantly longer TTR (HR=0.65 p=0.01). The association was similar for wild type (HR=0.58 p=0.01) and PIK3CA mutated tumors (HR=0.60 p=0.06), with no significant interaction of A/N use and PIK3CA (p=0.34). Conclusions: Among HR+ breast cancer patients, those who used A/Ns following primary diagnosis had longer TTR than non-users, regardless of tumor PIK3CA mutation status. The study provides a model for how tumor genomics could be integrated into secondary chemoprevention studies. [Table: see text]
FemZone trial: a randomized phase II trial comparing neoadjuvant letrozole and zoledronic acid with letrozole in primary breast cancer patients
