Comprehensive Analysis of Breast Cancer in Very Young Women (<35 years), a Single Institution Experience.

Background

Breast cancer in young women is associated with aggressive disease and poor outcomes. Whether very young age (≤35 years) confers distinct clinicopathologic features compared with other young patients remains incompletely characterized.

Methods

A retrospective analysis of all primary breast carcinomas diagnosed at a single academic institution (2014-2020) was performed. Clinicopathologic features, molecular subtypes, genetic testing results, and survival outcomes were compared between patients aged ≤35 years (very young) and 36-40 years. Multivariate Cox proportional hazard modeling assessed the independent prognostic significance of very young age.

Results

Of 2,742 women diagnosed with breast cancer, 271 (9.8%) were ≤40 years, including 128 (4.6%) aged ≤35. Very young patients demonstrated higher tumor grade (53.4% vs. 39.1%, p<0.05), lower estrogen receptor positivity, and a higher proportion of triple-negative (27.3% vs. 16.0%) and Luminal B (38.8% vs. 31.1%) subtypes. Metaplastic carcinoma was significantly enriched in the very young group (7.0% vs. <1%, p<0.05). Pathogenic germline mutations were detected in 22.7% of very young patients versus 11.3% of those aged 36-40, with BRCA1 predominating. On multivariate analysis, age ≤35 was an independent predictor of disease recurrence (HR 2.02, 95% CI 1.095-3.744, p=0.024), but not disease-specific survival..

Conclusions

Breast cancer in very young women may represent a biologically distinct subcategory, with more aggressive features and higher recurrence risk. Metaplastic carcinomas may be significantly enriched in this population, and there is a high prevalence of germline mutations. These findings suggest a need to tailor diagnostic and therapeutic strategies to the unique molecular and genetic characteristics of breast cancer in younger patients to improve early detection and long-term survival.