Data are scarce on breast cancers (BC) identified in females with elevated genetic susceptibility, and comparisons are lacking between periods before and after they entered a sustained risk-governance scheme based on genetic risk stratification. We investigated clinical endpoints within the cohort enrolled in the Phare Grand Ouest (PGO) project. The PGO project enrolls BRCA1 and BRCA2 pathogenic variant (PV) carriers, as well as high-risk females without a BRCA PV, from eight clinical cancer genetics services. The analytical dataset consisted of all women with either newly arising (incident) or pre-existing (prevalent) BC, matched 1:1 on age at first tumor detection. Associations between tumor dimensions and disease stage, and the following explanatory factors were examined using multivariable generalized linear and logistic regression models: chronological age, tumor molecular subtype, PV carrier status, incident/prevalent BC category, and measures of healthcare accessibility. Within the paired cohort, women with incident BC joined the program at a significantly younger chronological age, yet age at initial tumor discovery was similar. They bore smaller tumors, and the likelihood of being diagnosed with advanced-stage illness was roughly 30% lower relative to women in the prevalent BC group (OR = 0.29, P < 0.01). Early age and a triple-negative profile were both independently tied to larger tumor dimensions. Healthcare accessibility measures exerted no discernible impact. The coordinated, person-centered framework for governing high genetic risk embedded in the PGO was plausibly associated with earlier BC detection, both in PV carriers and in high-risk non-carriers. These results reinforce the incremental worth of person-focused surveillance pathways that fuse genetic risk appraisal with extended clinical monitoring, while simultaneously opening avenues for deeper exploration in this domain.
