Breast Cancer MRI Screening of Patients After Multiplex Gene Panel Testing.

Importance: Enhanced breast cancer screening with magnetic resonance imaging (MRI) is recommended to women with elevated risk of breast cancer, yet uptake of screening remains unclear after genetic testing. Objective: To evaluate uptake of MRI after genetic results disclosure and counseling. Design, Setting, and Participants: This multicenter cohort study was conducted at the University of Southern California Norris Cancer Hospital, the Los Angeles General Medical Center, and the Stanford University Cancer Institute. Patients were recruited from July 1, 2014, through November 30, 2016. Following multiplex gene panel testing and genetic counseling, patients responded to surveys about breast MRI screening at 3, 6, 12, and 24 months and to a final survey between 3 and 4 years after counseling. Participants met standard clinical criteria for genetic testing or had a 2.5% or greater probability of inherited cancer susceptibility. Patients were categorized based on breast cancer risk from genetic testing results and Tyrer-Cuzick model-calculated risk as having (1) a BRCA or other high-risk pathogenic variant (PV), (2) a moderate-risk PV, (3) a higher lifetime breast cancer risk (≥20%), or (4) a lower lifetime breast cancer risk (<20%). Analysis was conducted from September 28 to November 9, 2023. Interventions: Genetic testing with a 25- or 28-gene panel, and pretest and posttest genetic counseling by a genetic counselor or an advanced practice genetics nurse practitioner, which included cancer-specific screening recommendations. Main Outcomes and Measures: MRI screening adherence over time across risk groups was estimated using Cox proportional hazards regression modeling. Likelihood of screening adherence (odds ratios [ORs] with 95% CIs), controlling for potential confounders, was estimated using logistic regression. Results: This study included 638 patients, with a mean (SD) age of 50.7 (13.3) years at testing. There were 43 patients (6.7%) with a BRCA or other high-risk PV, 16 (2.5%) with a moderate-risk PV, 146 (22.9%) with higher lifetime breast cancer risk, and 433 (67.9%) with lower lifetime breast cancer risk. A total of 52 patients (8.2%) identified as Asian, 21 (3.3%) as Black, 271 (42.5%) as Hispanic, and 255 (40.0) as White. Compared with patients with lower lifetime breast cancer risk, patients with a BRCA or other high-risk PV and those with a moderate-risk PV were approximately 10 times (OR, 9.81 [95% CI, 4.05-23.86]; P < .001) and 4 times (OR, 4.12 [95% CI, 1.10-14.35]; P = .03) as likely to undergo MRI, respectively. Patients with a BRCA or other high-risk PV were nearly 16 times (OR, 15.81 [95% CI, 5.17-48.31]) as likely to report consistent yearly MRI screening compared with patients with lower lifetime risk. Conclusions and Relevance: In this study, women with inherited PVs conferring increased breast cancer risk had higher and more consistent MRI uptake than women with lower estimated risk. These findings emphasize the importance of genetic cancer risk assessment for effective enhanced breast cancer screening.