Abstract 7339: Mayo Clinic breast cancer cohort: A valuable resource for breast cancer research

Abstract The Mayo Clinic Breast Disease Registry (MCBDR) was developed to serve as a cohort of newly diagnosed breast cancer patients to address questions of etiology, prognosis, and survivorship. Eligibility is limited to patients 18 years or older with a confirmed first stage 0-4 breast cancer diagnosis within the last year. Consent is completed via phone, patient portal, or in-person. Upon enrollment, a baseline questionnaire and blood collection are completed. Annual follow-up surveys that capture BC outcomes are sent to all living participants. The MCBDR cohort (N=9, 215, enrolled between 2001 and 2023) is 99% female, with an average age at diagnosis of 58 years (SD=12. 7). Currently, MCBDR has an average time since diagnosis of 9. 8 years (SD=6. 4). The participants are 94% white, and 55% live in Minnesota. At the time of baseline questionnaire completion, 77% were married, 84% had a bachelor’s degree or higher, and 8% reported financial hardship. Further, 35% reported a history of smoking, 11% consumed more than two drinks per day, and 9% reported fair or poor social relationships. Within MCBDR, 53% of the participants had stage 0 or 1 cancer at diagnosis, while 28% had stage 2, 9% stage 3, and 3% stage 4 BC. Tumors were triple negative in 9%, HER 2 positive in 9%, hormone receptor-positive and HER2 low or negative in 55%, and 27% had missing HER2 status. Pathological TNM staging was available on 98%, among which 33% were staged at T2 or higher and 27% were node-positive. Definitive BC surgery was completed at Mayo Clinic for 73%, with 35% undergoing mastectomies and 44% having lumpectomies. 74% were treated with radiation, 56% underwent chemotherapy, and 79% were treated with endocrine therapy. Clinical genetic testing results have been nurse-abstracted for 94% of the cohort. Of those known to be tested, 521 (6%) had a pathogenic or likely pathogenic mutation identified in a BC causing gene. In addition, whole exome sequencing was completed on 71% of MCBDR participants in 2020, in which 167 previously unknown pathogenic or likely pathogenic mutations were identified. After the initial diagnosis and active treatment phase, nurse abstraction identified 151 (2%) participants known to have been diagnosed with a contralateral BC diagnosis, and 4% known to have been diagnosed with a second primary other than breast. Recurrence in the same breast has been reported for 242 (3%), with 72% of those recurrences occurring within 5 years of initial diagnosis and another 19% occurring 5-10 years post diagnosis. Among the 1, 262 (14%) who are deceased, 24% died from BC and 19% had distant metastases at diagnosis or a distant recurrence. Amongst all deceased, 6% died within 1 year of their diagnosis and 43% died within 5 years of diagnosis. For participants who died from BC, 10% died within 1 year of their diagnosis and 64% died within 5 years of diagnosis. MCBDR data has been used in numerous publications and is an essential resource for efficient observational research analyses. Citation Format: Nicole L. Larson, Janet Olson, Kathryn Ruddy, Fergus Couch, Denise Herman, Feven Abraha. Mayo Clinic breast cancer cohort: A valuable resource for breast cancer research abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7339.