BackgroundMentorship in the field of radiation oncology (RO) promotes career development and satisfaction. Many individuals, however, do not have access to mentorship or are unsatisfied with their mentorship experience, potentially due to insufficient gender-concordant mentorship opportunities. To address this, the Society for Women in Radiation Oncology (SWRO) created the SWRO Mentorship Program for women, gender minorities, and those with intersecting marginalized identities at all stages of training for physicians and medical physicists. We present the five-year experience of the largest multi-institutional mentorship program, to our knowledge, in RO. MethodsPublicly available information and the SWRO mentorship sign-up form were used. Descriptive statistics and binomial tests compared to reference points were conducted. ResultsBetween January 2018 and June 2023, 296 individuals from 19 countries participated in the mentorship program, generating 225 mentee-mentor pairs. The majority were female (89.2%), based in the United States (US; 84.8%), and on the physician-track (96.6%). The remainder of the analysis focused on US-based, physician-track participants (n = 244), the majority of whom were female (96.7%) and trainees (58.2%). Among those who have completed RO residency, most accepted a first job in academia (82.1%) and remained in academia at the time of the analysis (76.3%). A significantly higher proportion of SWRO mentorship participants compared to the reference point took a first job in academia (82.1% vs 58.3%; p<0.0001). The most common disease sites of focus for the physician-track trainees who finished residency are breast (50.4%), central nervous system (32.7%), and gynecologic malignancies (30.1%), with 54% listing more than one. The most common expressed goals of mentorship are research (35.8%), leadership (24.5%), and building connections within a specific geography or institution (19.2%). ConclusionsThe SWRO experience demonstrates the feasibility of a large-scale, multi-institutional mentorship program in RO.