Adjuvant interstitial three-dimensional pulse-dose-rate-brachytherapy for lip squamous cell carcinoma after surgical resection

Purpose
The purpose of this study was to report clinical outcomes of patients treated with pulse-dose-rate brachytherapy (PDR-BT) for lip cancer after insufficient surgery.

Material and methods
Twenty lip cancer patients were treated from January 2012 to September 2016. Primary treatment included surgery with or without reconstruction. All patients were diagnosed with squamous cell carcinoma, most of the tumors were pT1. Brachytherapy procedures were done after post-operative wound healing. Median of three plastic tubes were implanted using a free-hand technique. Two PDR-BT treatments were scheduled for every patient, with the gap of median 13 days. The planned dose was 0.8-1 Gy per pulse to the total dose of 50 Gy from two PDR-BT treatments. Patients were evaluated every 3-6 months. Follow-up time was counted from the last day of treatment to any event or last visit. Early and late toxicities were scored with RTOG scale.

Results
Average follow-up was 34.7 months (range, 12.7-67.6). Three- and five-year estimated disease-free survival was 95% and local control was 100%. One patient suffered from regional relapse in the submental region (IA lymph node group). Skin erythema or dry desquamation (grade 1) or wet desquamation (grade 2) was observed in 13 patients (65%) and one patient (5%), respectively. Six patients presented no acute toxicity. Moreover, there were no complications involving lip mucosa. All patients had grade 1 soft tissue fibrosis in the irradiated area, besides that, late toxicity included only skin complications. There were no significant factors associated with late toxicity ≥ grade 2.

Conclusions
PDR-BT in the adjuvant treatment of the lip cancer yields high local control with low toxicity. Even patients with close margins after surgery (< 5 mm) should be considered as candidates for PDR-BT.