e24046 Background: Fewer than 1% of all cases of breast cancer occur in men, and little is known about the late effects of the disease and its treatment in this population. We developed a pilot survey with the aim of identifying primary areas of concern among men who have been treated for breast cancer. The findings will be used to develop a more comprehensive survey assessing the late effects or collateral damage of male breast cancer treatment. Methods: An anonymous survey was developed with the assistance of patient advocates from the Male Breast Cancer Coalition (MBCC). The survey asked for the men’s current age and contained five open-ended questions. Respondents were asked to (1) describe the most significant types of collateral damage they had experienced; (2) share the effects of disease and treatment on areas of their lives (physical, emotional, psychological, financial); (3) identify resources they had found to be helpful; and (4) provide advice to other men with breast cancer. The fifth question allowed for additional free-text entry. The survey, distributed by the Dr. Susan Love Foundation for Breast Cancer Research and MBCC via social media postings and email, was open from January to February 2021. Results: Sixty-eight men responded to the survey. Mean age of respondents was 62.9 (range 34 - 87). Sexual dysfunction, peripheral neuropathy, musculoskeletal complaints, and fatigue were the most commonly reported collateral damage symptoms. In their open-ended answers, many respondents expressed anxiety about and fear of recurrence, being self-conscious regarding their appearance, and negative effects on sexual function and intimacy. Some described the social isolation of being a man with breast cancer, and several discussed job loss and financial hardship as a result of their diagnosis and treatment. Online resources, including MBCC, were popular sources of support, as were family, friends, and faith. The respondents’ advice to other men with breast cancer included many recommendations to “be your own advocate,” seek out others for support and networking, and “prepare for a pink world.” Conclusions: This pilot study provides important preliminary information regarding late effects and collateral damage of male breast cancer and its treatments, as well as insights into the male breast cancer experience not captured in prior work. This information will be used to inform a more comprehensive project that assesses collateral damage and quality of life among men who have been treated for breast cancer. The findings also will be used to develop recommendations on how to educate clinicians about the needs of male breast cancer survivors and how to better alleviate the late effects and collateral damage they experience.