Purpose: To evaluate the efficacy and toxicity of tirapazamine, a hypoxic cytotoxin, combined with conventional radiotherapy (RT) for advanced head and neck carcinomas.
Materials and methods: From Oct. 1994 to Nov. 1996, 40 patients with stage III or IV carcinomas of the head and neck were enrolled in a Phase II trial to receive conventional RT (70 Gy in 7 weeks) with concurrent tirapazamine (159 mg/m2 intravenously, 3 times per week for 12 doses). One patient subsequently withdrew from the protocol treatment, and was excluded from analyses. Among the 39 cases, the primary sites were located in the oropharynx (n = 28), supraglottic larynx (n = 6), or hypopharynx (n = 5). Twenty-seven patients had T3 or T4, and 27 had N2 or N3 disease.
Results: Thirty-two (82%) patients received full 12 drug doses. Thirty-two patients (82%) received full 70 Gy of RT. The most frequent drug toxicities were muscle cramps (77%) and nausea/vomiting (62%), usually grade 1 or 2. Overall, 13 patients (33%) experienced grade 3 or 4 drug-related toxicities. No excessive RT-associated acute normal tissue reactions were observed. With a median follow-up of 13 months, the 1-year and 2-year local control rate was 64% and 59% respectively.
Conclusion: The tirapazamine regimen was well tolerated with a compliance rate of 82%. The toxicity of RT with concurrent tirapazamine was acceptable in treating advanced head and neck carcinomas. The disease control trend was encouraging. Further clinical studies are warranted.