The impact of adjuvant radiotherapy on borderline and malignant phyllodes tumors of the breast.

Abstract

Background: Borderline and malignant phyllodes tumors (PTs) are rare fibroepithelial breast neoplasms associated with a high risk of locoregional recurrence (LRR). Although adjuvant radiation therapy (RT) is increasingly used, its clinical benefit remains uncertain. This study aimed to assess the impact of RT and identify factors associated with LRR in patients with borderline and malignant PTs.

Methods: A retrospective review was conducted on 102 patients (50 borderline, 52 malignant PTs) who underwent surgery between 2012 and 2021. Clinical, pathological, and treatment data were analyzed. The primary endpoint was LRR. Kaplan-Meier and Cox regression models were used to assess recurrence and risk factors.

Results: Median follow-up was 4.3 years. Malignant PTs were more likely to be > 10 cm (63.5% vs. 22%), undergo mastectomy (75% vs. 11%), and receive adjuvant RT (78.9% vs. 8%) compared to borderline PTs (all P < 0.001). Among patients without RT, malignant PTs had a significantly higher LRR than borderline PTs (36.4% vs. 4.4%, P < 0.010). In malignant PTs, RT was associated with a lower LRR (12.2% vs. 36.4%), though not statistically significant (P = 0.081). Tumor subtype was the only independent predictor of LRR (P = 0.011). Among malignant PTs who received RT, treatment initiation beyond 12 weeks post-surgery was associated with increased LRR (P = 0.009). Radiation technique, dose, and use of bolus were not significantly associated with LRR.

Conclusion: Malignant PTs demonstrated higher LRR than borderline PTs. While the benefit of RT was not statistically significant, a trend toward reduced recurrence was observed.