Abstract P6-19-03: The role of lumpectomy and radiation therapy in men 70 years of age and older with early breast cancer on hormone therapy: A NCDB analysis

Abstract

Abstract Background: Current consensus guidelines for the treatment of male breast cancer are driven by female-only clinical trials despite data suggesting distinct biologic, clinicopathologic, and prognostic differences between male and female breast cancer patients. This includes a recent retrospective multicenter analysis showing greater overall survival among male breast cancer patients who underwent lumpectomy with radiation therapy (RT), compared to total mastectomy or lumpectomy alone. In light of these findings and the CALGB 9343 trial performed in women, we sought to evaluate if survival was also equivalent in men ≥70 years old with early stage breast cancer treated with hormone therapy and lumpectomy with or without radiation therapy (RT), as shown in women. Methods: We performed a retrospective analysis of 752 stage I (T1N0M0), estrogen receptor (ER) positive male breast cancer patients ≥70 years of age who were treated with hormone therapy and underwent lumpectomy with or without RT or total mastectomy (without RT) from the National Cancer Database (NCDB) between the years 2004 to 2014. Chi-squared, Kruskal-Wallis, and analysis of variance tests were used to compare demographic and clinicopathologic differences between groups. Multivariable Cox proportional hazards regression analysis was used to compare overall survival between treatment groups, controlling for demographic and clinicopathologic differences. Results: Most patients underwent total mastectomy (67.4%), with only 32.6% treated with lumpectomy. Of those who underwent lumpectomy, 72.6% (n=178) underwent adjuvant RT. There were significant differences in age, tumor size, histology, grade, surgical margins, nodal surgery, and chemotherapy between patients who underwent lumpectomy without RT, lumpectomy with RT, and total mastectomy (p<0.05). Lumpectomy without RT patients were older (78.9 vs. 76.0 & 76.9 years, p<0.01), more frequently presented with invasive ductal carcinoma (77.6% vs. 71.3% & 85.4%, p<0.0001), and less frequently underwent axillary nodal surgery including sentinel lymph node biopsy (71.7% vs. 91.6% & 94.9%, p<0.0001) compared to lumpectomy with RT and total mastectomy patients. In multivariate analysis, there were no significant differences in overall survival for lumpectomy without RT, lumpectomy with RT (HR 0.71, 95%CI 0.39-1.27, p=0.25), and total mastectomy alone (HR 0.92, 95%CI 0.55-1.56, p=0.76). Older age, higher Charlson-Deyo comorbidity scores, and poorly differentiated tumors were associated with poorer overall survival, while treatment at an academic/research center was associated with improved overall survival (p<0.05). Conclusion: In this national sample of elderly ER positive male breast cancer patients with early disease on hormone therapy, lumpectomy alone was associated with equivalent survival compared to lumpectomy with RT and total mastectomy alone. These results suggest that breast conserving surgery without radiation therapy is appropriate for this subset of male breast cancer patients and greater adoption by breast surgeons should be considered. Citation Format: Bateni SB, Arora M, Daly ME, Bold RJ, Canter RJ, Sauder CA. The role of lumpectomy and radiation therapy in men 70 years of age and older with early breast cancer on hormone therapy: A NCDB analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-19-03.