Revisiting Exclusion of Prior Cancer in Clinical Trials of Male Breast Cancer

Background: Eligibility criteria for cancer clinical trials present challenges to enrollment. Many trials exclude patients with a prior cancer. This common practice may be especially detrimental to trials of rare cancers, such as male breast cancer, that struggle to accrue adequate numbers of participants. Objectives: To estimate prevalence of prior cancer among men newly diagnosed with breast cancer and describe characteristics of men with prior cancer compared to those without. Methods: We identified men diagnosed with breast cancer between 2011-2015 using population-based data from National Cancer Institute's Surveillance, Epidemiology, and End Results program of cancer registries. We used sequence number and diagnosis year to identify cancers diagnosed prior to breast cancer (inclusive of prior breast, different, and unknown types of cancer). We compared sociodemographic, tumor, and treatment characteristics of men with and without prior cancer using chi-square tests. Results: Among 2317 men, nearly one quarter (24.3%) had any prior cancer, and the majority (58.7%) of these were of a different cancer type. A higher proportion of men with a prior cancer of a different type were older, had smaller (≤ 2 cm) breast tumors, were diagnosed with stage 0-1 breast cancer, and did not receive surgery compared to men without any prior cancer; there were no statistically significant differences by race and ethnicity, county median income, hormone receptor status, or surgery type. Conclusion: Given prevalence of prior cancer in this rare and understudied population of men diagnosed with breast cancer, including men with prior cancer in clinical trials may improve accrual.