A case-control study of patients with squamous cell carcinoma of the oral cavity and oropharynx treated with pulsed-dose-rate brachytherapy.

Abstract

Pulsed-dose-rate (PDR) brachytherapy is thought to mimic the radiobiological benefits of continuous low-dose-rate (cLDR) delivery but is safer for medical personnel. We set out to evaluate the outcomes of this technique in patients with head and neck squamous cell carcinoma. A total of 36 consecutive patients treated with PDR brachytherapy were randomly matched to 72 cLDR controls according to T-stage, tumor site, and management strategy. Local recurrence and late complications were compared between the two groups. Baseline characteristics were similar in both groups. Oral cavity cancers predominated at 81%, and 89% had T1/T2 tumors. Seventy-five percent of patients underwent surgery before radiation treatment. Median followup was 59 and 30months for cLDR and PDR patients, respectively. Three-year actuarial local recurrence-free survival was 97% and 94% for cLDR and PDR patients, respectively (p=0.77). Three-year cumulative risk of Grade ≥2 complications was 45% and 32% for cLDR and PDR patients, respectively (p=0.2). For cLDR, a dose rate exceeding 68cGy/h resulted in more complications (RR 5.3, p<0.05). Similarly, PDR patients receiving ≥75cGy/pulse were at higher risk. PDR brachytherapy in head and neck squamous cell carcinoma yields comparable results to cLDR treatment. Dose rate was correlated with the risk of late complications, regardless of technique.