Genetic counseling referral rates and genetic testing outcomes in women with young breast cancer: a 20-year Canadian review.

Purpose: Despite guidelines recommending genetic testing for all cases of very young breast cancer (VYBC), poor uptake has been reported. This study aimed to examine genetic testing referral rates and outcomes over a 20-year period within the Canadian context.

Methods: A retrospective chart review of all incident VYBC cases (at or below 35 years of age) between January 1, 2000 and December 31, 2019 was conducted. Descriptive statistics were used to summarize demographic factors and logistic regression analyses were performed to identify the predictors associated with referral for genetic counseling and positive genetic test results.

Results: 628 women were identified with VYBC. Most women presented with stage 2 (42%), hormone receptor-positive (HR +) and HER2-negative (54%) invasive ductal carcinoma (94%). Over the study period, referral rates increased from 44 to 84%. Of women initially tested for BRCA1/BRCA2, only 21% were referred for updated panel testing. Among those tested, 19% had a pathogenic variant, 21% of whom reported no family history of cancer. Predictors of referral included stage 0-2 disease while predictors of positive test results included a second breast cancer diagnosis and positive family history.

Conclusion: Despite guidelines based on age alone, barriers to referral persist. Results of this study suggest the need for new models of care that ensure equitable access to genetic testing for all women diagnosed with VYBC regardless of family history, ethnicity, or disease stage. As genetic testing criteria evolve, protocols must address these barriers to prevent missed opportunities for testing.