Mainstreamed genetic testing of breast cancer patients: experience from a single surgeon's practice in a large US Academic Center.

This study evaluated the impact of mainstreamed genetic testing (MGT) on the timing and uptake of testing in an academic breast surgeon's practice. Before September 2019 (pre-MGT phase), a breast surgery practice at Massachusetts General Hospital followed a traditional model of a pre-test consultation with a genetic counselor (GC) following a referral. After September 2019 (post-MGT phase), the same practice offered patients genetic testing in a single clinical encounter with a breast surgeon. We evaluated the waiting time between referral and GC visit in the pre-MGT phase and compared the uptake and positivity rates between both phases. In the pre-MGT phase (204 patients), the median waiting time for GC visit was seven days for patients with a newly diagnosed cancer, 211 days for patients with a personal history of cancer, and 224 days for non-cancer patients who had a family history. A total of 105 (51.5%) patients completed a GC appointment. In the post-MGT phase (202 patients), a significantly higher proportion of patients (88.1%, p < 0.001) consented to genetic testing, while the proportion of patients who tested positive was lower (pathogenic variant: 11.9% vs. 20.0%; variant of uncertain significance: 19.9% vs. 28.0%; p = 0.047). Implementing MGT can reduce the number of clinical visits, significantly shorten patients' wait time to test initiation, and increase the completion of genetic testing. Successful integration of this model relied on the genetic expertise of the breast surgeon involved and the support of the GC team.