A comparison of misonidazole sensitized radiation therapy to radiation therapy alone for the palliation of hepatic metastases: results of a Radiation Therapy Oncology Group randomized prospective trial

Between May 1980 and July 1983, the RTOG conducted a randomized prospective study comparing external radiation therapy and misonidazole to radiation therapy alone for patients with hepatic metastases. Two hundred fourteen patients were accessioned to this study of whom 187 were evaluable. Radiation therapy was delivered to the whole liver to a dose of 21.0 Gy in 7 fractions. Misonidazole was administered orally, 1.5 gm/m2 daily 4-6 hr before each treatment. Patients in the two treatment groups were evenly distributed with respect to stratification variables including primary site, extent of metastatic disease, and Karnofsky Performance Score (KPS). End points examined included amelioration of hepatic pain, improvement of KPS and alkaline phosphatase, decrease in liver and tumor size, and survival. The addition of misonidazole did not significantly improve the therapeutic response to radiation therapy in any of the parameters studied. Hepatic irradiation was effective in relieving abdominal pain with 80% of the symptomatic patients achieving improvement following therapy. Pain was completely relieved in 54% of these patients. Patients with liver metastases from colon carcinoma improved more frequently than those with metastases from other primary tumor sites (p = 0.02). Relief of pain occurred more frequently in patients treated with radiation therapy and misonidazole (87%) compared with radiation therapy alone (74%) (p = 0.08). Palliation of pain was prompt, occurring within a median of 1.7 weeks from the initiation of treatment, and 94% of patients who improved did so within 6 weeks of treatment. The median duration of response was 13.0 weeks in the symptomatic patients; 52% of those surviving 3 months remained improved. KPS improved in 28% of patients. Serial CT scans revealed a partial response in 7% and a marginal response in 13% of patients. One patient had a complete response to treatment. The median survival of patients treated in this series was 4.2 months with no difference between the two treatment groups. Patients with metastases from colon carcinoma and an initial KPS of 80 or more (48% of the patient population) had a median survival of 5.8 months with radiation therapy alone compared with 6.6 months with radiation therapy and misonidazole (p = 0.36). There was no significant treatment related morbidity. Radiation therapy remains an excellent palliative tool for the management of patients with symptomatic hepatic metastases. Further research must continue to identify new methods of selectivity enhancing the tumor response to radiation therapy.