Primary Breast Sarcoma in Pediatric, Adolescent, and Young Adult Patients: A Single-Institution Review

Primary breast sarcoma (PBS) accounts for approximately 1% of all breast malignancies. Research in pediatric, adolescent, and young adult (AYA) populations is limited and often based on large national databases. This study aims to characterize clinical presentation, treatment patterns, and outcomes of PBS in these populations.

We performed a retrospective review of patients ≤39 ys diagnosed with PBS or malignant/borderline phyllodes tumors (PTs) at our institution (2000-2024). Patients with prior breast cancer or breast irradiation were excluded. Clinical, pathologic, treatment, and outcome data were collected. Disease-free survival (DFS) and overall survival (OS) were estimated using Kaplan-Meier methods, with comparisons by log-rank tests. Cox proportional hazards models were used to assess associations with mortality.

A total of 208 patients were included (median age, 31.3 y; age range, 11.7-39.9 y). Angiosarcoma (n = 70, 33.7%) was the most common histology. A pathogenic mutation was identified in 32.0% of patients tested, most commonly Li-Fraumeni syndrome. At a median follow up of 38.2 mo, 77 (37.7%) patients developed recurrence. The 5-y OS was 80.9%, and 5-year DFS was 64.4%. Mastectomy was associated with a higher hazard of death compared to breast-conserving surgery on multivariable analysis (hazard ratio 5.05; 95% confidence interval, 1.51-16.91; P = 0.01).

In this single-institution cohort of pediatric and AYA patients, mastectomy was associated with worse observed OS. Nearly one-third of patients who received genetic testing had a pathogenic mutation. Recurrence was noted in over one-third of patients. These findings provide institutional-level outcome data and highlight the need for larger multi-institutional studies in this rare population.