A national cohort study examining breast cancer diagnostics, treatments, and outcomes in individuals on hormone therapy - over 5% of adult americans take hormone therapy (HT) and this number is…

The Medical College of Wisconsin, Inc. received a $156,000 Project Grant award dated June 18, 2025, from the National Cancer Institute (NCI) under the Cancer Cause and Prevention Research program (CFDA 93.393) to conduct a national cohort study examining breast cancer diagnostics, treatment, and outcomes in individuals using hormone therapy (HT). The project, which will be completed by May 31, 2027, will create a multi-institutional retrospective cohort of breast cancer patients on HT from 23 institutions to collect detailed patient demographic, treatment, and outcome data. The research addresses significant knowledge gaps regarding how HT influences breast cancer screening methods, treatment planning (particularly for hormone-receptor positive cases), and survival outcomes across diverse patient populations including pre-menopausal females and males—populations underrepresented in existing breast cancer research.

The grant deliverables include three primary aims: establishing a national cohort database with granular clinical and demographic information from HT-using breast cancer patients; analyzing and comparing breast cancer stage, treatment patterns, and survival outcomes between the HT cohort and a matched general breast cancer cohort from the Surveillance, Epidemiology, and End Results (SEER) database; and creating a Patient and Community Advisory Board to support data interpretation, dissemination of findings, and design of future patient-centered research. These research products will generate foundational evidence to inform evidence-based screening and treatment guidelines for individuals on hormone therapy diagnosed with breast cancer.

A national cohort study examining breast cancer diagnostics, treatments, and outcomes in individuals on hormone therapy - over 5% of adult americans take hormone therapy (HT) and this number is anticipated to increase in the upcoming decades. The potential impact of HT on breast cancer (BC) risk, treatment, and outcomes is unclear - especially amongst younger females and in males. Current data on BC in individuals on HT is primarily based upon studies examining post-menopausal females, which limits the knowledge of how HT may influence BC in pre-menopausal females males. This is exceedingly relevant given the increasing use of HT and the increasing incidence of BC in the united states. Specifically, there is limited data on how BC is diagnosed in these individuals (screening VS physical examination), 2) how HT may alter BC treatment plans (especially for those with hormone-receptor positive BC), and 3) BC outcomes among individuals on HT compared to the average population with BC. Thus, to fill these significant knowledge gaps and address a major unmet need in a growing population, we propose creating a novel national multi-institutional retrospective cohort of patients on HT with BC to investigate these data gaps and create a patient and community advisory board to support data interpretation and next steps. Aim 1 will create a national cohort of patients on HT with BC from 23 institutions to collect granular patient demographic, HT, and BC data. Aim 2 will analyze BC stage and patient age at diagnosis, clinicopathologic and BC treatment data, and BC-specific survival in the HT cohort from aim 1 and compare findings to a general BC cohort from the seer database matched by SEX. Aim 3 will create a patient and community advisory board to aid in data interpretation, public dissemination of our findings, and support future patient-centered research. Findings will result in foundational data to inform evidence-based BC screening and treatment guidelines for individuals on HT. Furthermore, results of this innovative work will support the development of a national prospective cohort and tumor bank to refine BC screening and treatment guidelines and support translational research efforts for patients on HT.