Real-world efficacy of postoperative radiotherapy with a moderate dose-escalation for phyllodes tumors of the breast.

Background: Phyllodes tumors are rare breast tumors comprising less than 1% of cases, categorized as benign, borderline, or malignant. Treatment typically involves complete surgical excision with wide margins. Adjuvant radiotherapy may be recommended for borderline or malignant tumors, or when clear margins cannot be achieved through surgery alone. Methods: We conducted a retrospective review of 14 women diagnosed with phyllodes tumors between 2015 and 2023. Among them, 36% had benign tumors and 64% had borderline/malignant tumors. The majority (86%) underwent breast-conserving surgery. Postoperative radiation therapy was delivered to the whole breast/chest wall, with a median biologically effective dose (BED) of 92.7 Gy (90.0-102.6 Gy), representing a moderate dose-escalation over conventional breast cancer schedules. Results: After a median follow-up of 48.5 months, no local or distant recurrence were observed. Mild to moderate skin toxicity occurred in all patients: 36% reported grade 1, 43% grade 2, and 21% grade 3 toxicity. One patient developed grade 2 fibrosis during follow-up. No significant correlations were found between the severity of acute/late toxicity and tumor size, surgical approach, or the radiation field's planning target volume (PTV). Conclusions: Adjuvant radiation therapy appears to be well tolerated and feasible for high-risk phyllodes tumors. However, the decision to utilize radiotherapy should be personalized, considering tumor characteristics and the risks and benefits associated with treatment.