Age-Related Germline Landscape of Endometrial Cancer: Focus on Early-Onset Cases

Early-onset endometrial cancer (eoEC) is increasing, and germline drivers may be enriched in younger patients. We sought to define germline pathogenic variants (gPVs) in those with EC by age.

We identified patients with EC who underwent clinical tumor-normal sequencing from December 2014 to June 2021 and collected clinical variables. Logistic regression models evaluated associations between age at EC diagnosis and presence of gPV, biallelic inactivation, and Lynch Syndrome (LS). Age categories were defined as early-onset (eoEC, EC < 50 years) and late-onset (EC ≥ 70 years) and were compared with those diagnosed ages 50-69 years.

Among 1,625 patients with EC, the median age at diagnosis was 63 (range, 24-96) years. We observed gPV in 28 (16%) of 170 patients with eoEC, 152 (14%) of 1,066 patients diagnosed age 50-69 years, and 36 (9%) of 389 patients with late-onset EC (P = .016). LS was enriched in eoEC, with 6.5% of patients diagnosed age <50 years having LS. In multivariable models compared with those with EC diagnosed age 50-69 years, eoEC was more likely to exhibit biallelic inactivation (odds ratio, 3.34 [95% CI, 1.44 to 7.35]) and be associated with LS (hazard ratio [HR], 3.49 [95% CI, 1.63 to 7.01]). Among early-onset EC, 14 (50%) of 28 gPV were high penetrance and 14 (50%) of 28 exhibited biallelic inactivation. However, heterogeneity was observed, and rates of gPV were 8.9% and 19%, biallelic inactivation was 0% and 11%, and LS was 2.2% and 8% in those diagnosed age <40 years and 40-49 years, respectively.

Rates of gPV, biallelic inactivation, and LS differ across age groups for EC, with high-penetrant genes driving tumorigenesis enriched in younger patients. However, very-early-onset EC may have different drivers and necessitates more research.