Radiation therapy in head and neck with telecobalt beam quality: Tolerance to 70 Gy dose in a five-week overall treatment time

Vollständiger Abstract

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Head and neck malignancies are associated with accelerated tumor repopulation when overall treatment time (OTT) extends beyond 28 days, potentially compromising the effectiveness of radiotherapy. To address this limitation, a treatment strategy was developed to reduce OTT by delivering a total radiation dose of 70 Gy over five weeks. In a pilot study involving high-grade head and neck malignancies, a total dose of 70 Gy was delivered using cobalt radiotherapy with tissue compensation at 2 Gy per fraction, administered either 7 fractions/week or 6 fractions/week. Good compliance with the full 70 Gy treatment course was observed. Radiation sequelae in the 7 fractions/week group included Grade III skin reactions in 16% of patients and Grade III mucositis in 26%, both considered acceptable. Based on these results, a randomized non-inferiority trial was conducted to compare acute toxicities between the 7 fractions/week and 5 fractions/week treatment arms, both delivering a total dose of 70 Gy. A total of 107 patients receiving concomitant chemoradiotherapy (CTRT) and 34 patients receiving neoadjuvant chemotherapy followed by concomitant chemoradiotherapy (NACT-CTRT) were treated with 70 Gy over five weeks. Another 99 CTRT patients and 42 NACT-CTRT patients received the same total dose of 70 Gy over seven weeks. In the 7 fractions/week arm, the observed Grade III–IV skin toxicity was 1.6%, and Grade III–IV mucosal toxicity was 12.7%, both significantly lower than the literature-reported value of 69% (p < 0.0001). For the 5 fractions/week arm, Grade III–IV skin toxicity was 3.2%, while Grade III–IV mucosal toxicity was