Chemotherapy type and survival in young BRCA1/BRCA2 carriers with HER2-negative early breast cancer.

Homologous recombination deficiency due to germline pathogenic BRCA1 and BRCA2 variants, the theoretical basis for increased sensitivity to double-strand break-inducing agents.

The international BRCA BCY Collaboration (NCT03673306) is a retrospective multicentre cohort study of carriers of germline BRCA1 or BRCA2 pathogenic variants diagnosed with stage I-III breast cancer at age 40 years or younger between 2000 and 2020. The authors compared disease-free and overall survival by (neo)adjuvant chemotherapy type in 4200 HER2-negative patients from 109 centres, 58.7% of whom had triple-negative disease, with a median follow-up of 8.1 years. Anthracycline-taxane, anthracycline-no-taxane and non-anthracycline regimens were used in 74.4%, 19.3% and 6.3% of patients respectively, and platinum agents were given in 19.8% of triple-negative cases. After multivariable adjustment, no significant differences in disease-free or overall survival were seen between anthracycline-no-taxane and anthracycline-taxane (adjusted HR 0.88; 95% CI 0.73-1.05 and 1.20; 95% CI 0.87-1.67) or non-anthracycline regimens, and platinum use in triple-negative disease was not associated with improved outcomes. The authors see this as a basis for prospective de-escalation studies in this genetically defined population.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

The value of this cohort lies in its size and age homogeneity, both rare in the young BRCA population, and the null platinum signal is worth knowing when the question arises in the genetics clinic after a germline result. But the reverse reading must be resisted: a non-significant result in a retrospective cohort with only 6.3% non-anthracycline regimens and clinician-driven treatment allocation primarily reflects indication bias and lack of power in the minority arms, not demonstrated equivalence. The operational message is therefore the authors' own, generating de-escalation hypotheses to test prospectively rather than changing regimens today for a carrier patient.

Analysis by Dr Thibaut Benquey