Tumor characteristics, therapy, and prognosis in young breast cancer patients ≤ 35 years

Purposes Young breast cancer patients aged 35 years and younger are a small group of women who tend to present at high-risk form of the disease. More analysis of the data on tumor characteristics, treatment, and survival is necessary to help improving treatment and outcome. Methods In this retrospective study, we compared the clinical and tumor characteristics, the treatments, and the survival of 257 women aged ≤ 35 years, with 6566 women aged 50–69 years. We used a registry-based data of patients with invasive, non-metastatic breast cancer diagnosed between 2000 and 2015. Results Young women showed lower rate of hormone receptor (HR) positivity. Their tumors were more often HER2-positive, which showed lower rate of differentiation and higher rate of Ki-67 expression compared to their older counterparts. Women aged 35 years and younger were more likely to undergo neoadjuvant therapy and mastectomy. Endocrine therapy was underrepresented in young patients. 5-Year disease-free survival (DFS) was significantly lower in the younger patient group (81.7% vs. 91.3%, p < 0.001), while 5-year overall survival (OS) was not impaired (91.4% vs. 91.1%, p = 0.847). Conclusion The unfavorable disease-free survival in the group of younger patients might be explained by their unfavorable tumor characteristics. The surgical treatment appears to be more aggressive in young breast cancer patients and is more frequently combined with chemotherapy and immunotherapy, either in a neoadjuvant or in an adjuvant setting.