Misonidazole and unconventional radiation in advanced squamous cell carcinoma of the esophagus: a phase II study of the Radiation Therapy Oncology Group

This is a report on Radiation Therapy Oncology Group (RTOG) Protocol78-32, a Phase I/II prospective study aimed at determining tolerance, tumor response, and survival of squamous cell carcinoma of the esophagus treated with unorthodox fractionation radiotherapy combined with misonidazole. Misonidazole was administered by mouth 4 to 6 hr prior to radiation, at a dose of 1.0 to 1.25 Gm/.m2; blood levels were measured at about 4 hr after intake of the drug and reported in micrograms/ml. Radiotherapy was administered at 4 to 6 hr post-misonidazole dose and given with 400 rad fractions, alternating 2 or 3 times/week, up to 4,800 rad. A total of 43 patients were entered; 26 are evaluated for survival at 1 year post accession. Thirty patients (88%) received the planned radiation course. Twenty-eight patients (78%) received the planned misonidazole dosage. Tumor response, evaluated in 18 patients, showed a complete regression (C.R.) in only 2 patients (11%); and partial response (P.R.) in 6 patients (33%). Eight patients (44%) showed no tumor response to planned therapy. Toxicity was acceptable and in 38 evaluated patients only 4 reported (11%) nausea and vomiting, 7 reported mild paresthesias (18%). The median survival was only five months. In 26 patients evaluated for 1 year survival determination, only 1 survived (3.8%) this period. In view of the poor tumor response and low survival observed, we do not recommend that this particular fractionation regimen with misonidazole be used in a Phase III randomized trial in squamous cell carcinoma of the esophagus