Clinical characteristics and outcome of metaplastic breast cancer: A retrospective tertiary care center experience.

Abstract

1095 Background: Metaplastic breast cancer (MBC) is a rare neoplasm which accounts for less than 1% of all breast cancers. MBC is associated with worse prognosis and there is a paucity of literature on management. We evaluated the clinical characteristic and outcomes of MBC patients at our institution. Methods: After IRB approval, 136 patients diagnosed with MBC were reviewed from the Cleveland Clinic tumor registry from 2000-2017. Patients were evaluated for overall survival (OS) and progression free survival (PFS) using univariable analysis. Time to event variables were estimated by Kaplan-Meier method. Results: A total of 136 pathologically proven MBC patients were included in the study. Median age at diagnosis was 60 years (27-92). Eighty two percent (n = 112) had nuclear grade III, 7% (n = 10) had high grade dysplasia, 2% (n = 3) had nuclear grade I, and 4% (n = 5) had nuclear grade II; 60% (n = 82) patients were diagnosed at stage II, 21% (n = 28) at stage I, 14% (n = 19) at stage III, and 5% (n = 7) at stage IV. Estrogen receptor, progesterone receptor and Her2 expression were positive in 16% (n = 22), 9% (n = 12), and 10% (n = 14) respectively. Only 37% (n = 50) patient had lumpectomy, 18% (n = 25) received hormonal therapy, 56% (n = 76) received radiation, 51% (n = 70) received anthracycline chemotherapy and 26% (n = 36) received non-anthracycline chemotherapy; 37% (n = 50) had chemotherapy after 4 weeks of surgery and 35% (n = 48) patients had chemotherapy within 4 weeks of surgery. On univariable analysis, the 5-year OS for stage III was 30% (14% - 64%), hazard ration (HR) of 4.53 (95% CI, 1.71 - 12.01) (p = 0.002), for stage IV HR of 43.26 (95% CI, 12.34 - 151.64) (p = 0.001); chemotherapy within 4 weeks of surgery was associated with a higher risk of death, HR of 0.30 (95% CI, 0.12 - 0.74) (p = 0.009). Hormonal therapy, radiation therapy, surgery and type of chemotherapy was not associated with significant change in OS and PFS. In our cohort, 2-year OS was 79 % (73 % - 87 %) and 5-year OS was 69 % (61 % - 77 %); 2-year PFS was 61 % (52 % - 70 %) and 5-year PFS was 72 % (65 % - 81 %). Conclusions: Stage of MBC and chemotherapy within 4 weeks of surgery was associated with statistically significant OS and PFS on univariable analysis. Randomized clinical trials are warranted to improve outcomes in MBC patients.