Key clinical point: Some relatives of women with early-onset breast cancer (BC) may have an increased risk of developing discordant early-onset cancers (other than breast cancers).
Major finding: Among relatives of women with early-onset BC, offspring had a higher risk for any discordant early-onset cancer (standardized incidence ratio [SIR] 1.27; 95% CI 1.03-1.55), siblings' children had an increased risk for early-onset testicular cancer (SIR 1.74; 95% CI 1.07-2.69) and ovarian cancer (SIR 2.69; 95% CI 1.08-5.53), and siblings had an increased risk for early-onset pancreatic cancer (SIR 7.61; 95% CI 1.57-22.23).
Study details: Findings are from an analysis of a population-based cohort including 54,753 relatives from 5562 families of females diagnosed with early-onset BC.
Disclosures: This study was funded by the Cancer Foundation Finland and Academy of Finland. The authors declared no conflicts of interest.
Source: Rantala JNJ et al. Familial aggregation of early-onset cancers in early-onset breast cancer families. Int J Cancer. 2023;153(2):331-340 (Apr 19). Doi: 10.1002/ijc.34538