Breast cancer in women aged 25 years and younger.

To evaluate breast cancer characteristics in women aged 25 years and younger.,This was a retrospective, nested, within-cases matched study. The study design was based on a two-phase protocol. In the first phase, stage, grade, histologic subtype, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 status were compared between 28 patients (aged 25 years and younger) and 685 older premenopausal women (aged older than 25 years) with breast cancer. The second phase aimed to determine whether young patients exhibited worse prognosis when compared with older premenopausal women.,Young patients presented at a more advanced stage (P=.012) and exhibited a higher grade (P=.018). No significant differences were noted regarding histologic subtype, estrogen receptor, and progesterone receptor status. Genetic testing for BRCA1 and BRCA2 mutations was performed in 12 of 28 young patients and mutations were found in 25% of them. Moreover, young women presented poorer overall survival (hazard ratio [HR] 4.30, 95% confidence interval [CI] 1.09-17.03) than their older counterparts, matched by histologic subtype, stage, and grade; a similar pattern was noted regarding relapse-free survival (HR 8.28, 95% CI 2.24-30.60).,Breast cancer diagnosis in women aged 25 years and younger is uncommon; however, these patients present at a more advanced stage, with a higher grade, and exhibit poorer survival.