Abstract P6-19-02: Clinicopathologic features and radiation therapy utilization in patients with male breast cancer: A national cancer database (NCDB) study

Abstract

Abstract Introduction: Male breast cancer (MBC) is an uncommon malignancy, accounting for approximately 1% of all breast cancers (BC). The purpose of this study was to compare the clinicopathologic features of and radiation therapy (RT) utilization by patient age in patients with non-metastatic MBC and female breast cancer (FBC) using a large national database. Methods: The NCDB is a comprehensive national database that captures approximately 70% of newly diagnosed cancer patients in the US. Data for patients meeting study criteria were extracted including patient demographics, tumor characteristics, treatment modalities used, and overall survival (OS). Comparison of clinicopathologic factors between MBC and FBC were made using the Chi-Square test. Overall survival curves were estimated using Kaplan-Meier method. All results are presented as MBC vs FBC patients. Results: A total of 23,305 MBC patients and 2,678,061 FBC patients with non-metastatic breast cancer were identified in the NCDB database. The median patient age was 65 vs 60 yrs (MBC vs FBC, p < 0.001). Median tumor size was 19mm vs 15 mm (p < 0.001). In patients who had a LN evaluation, the median number of LN examined was 4 vs 3 and the median number of positive LN's were 1 vs 0. Percentage of patients undergoing breast conserving surgery was 25.6% vs 54.8%. Central tumor location was most common in MBC (30.3% vs 6.3%) and UOQ location was most common in FBC (17.2% VS 33.6%). The pathologic tumor characteristics for patients with MBC and FBC is shown in Table 1. Invasive lobular histology was less common in MBC patients (3.1% vs 7.5%). Higher percentage of female patients had non-invasive and Grade I cancers. MBC patients were more likely to have ER or PR positive tumors and less likely to have triple negative tumors. Lymph vascular invasion (LVI) was more likely to be present in MBC patients. There was a tendency towards earlier stage tumors in female patients. Regardless of gender, postoperative RT use was lower in patients 70 years or older compared to younger patients. Doing a stage-by-stage comparison, median survival was lower for patients with MBC compared to FBC. Conclusion: MBC is an uncommon malignancy accounting for approximately 1% of all breast cancers. Compared to FBC, patients with MBC presented with more advanced stage BC, and were more likely to have LVI. Median survival rates were lower for patients with MBC compared to FBC. MBCFBCp-valueBehaviorInvasive86.5%80.3%< 0.001GradeII13.7%18.1%< 0.001 II41.535.5 III/undif30/0.9%29.6/1.3% ER or PR positive 92.2%81.6%< 0.001Her2/neu positive 11.6%14.6%< 0.001Triple Negative 5.3%12.9%< 0.001LVIPresent27.7%16.6%<0.001Tumor StageTis11.1%16.4%< 0.001 T141.547.3 T228.119.7 Nodal StageNx17.0%18.1%< 0.001 N053.861.0 N121.115.8 N25.73.5 Stage Grouping010.5%16.9%< 0.001 I35.848.7 II39.426.6 III14.37.8 RT after BCSAll patients60.4%73.5%< 0.001RT after MastectomyT34 N12344.9%45.6% Older RT after BCSAll patients51.6%63.1%< 0.001Older RT after MastectomyT34 N12340.1%31.9%< 0.001Median OS (Mo)Stage 0 / I180 / 168NR / 189< 0.001 Stage II / III120 / 78180 / 98< 0.001Older - 70 years or greater; NR - Not reached Citation Format: Algan O, Herman T. Clinicopathologic features and radiation therapy utilization in patients with male breast cancer: A national cancer database (NCDB) study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-19-02.