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Background. The third and final randomization of Radiation Therapy Oncology Group (RTOG) 83–02 was performed to identify the maximal tolerated dose and potential efficacy of accelerated hyperfractionated radiation therapy (AHRT) in 1.6 Gy twice-daily fractions for adult malignant glioma. Methods. From December 1987 to July 1989, 304 patients with malignant glioma were stratified by age, performance status, and histologic findings and randomized to receive total AHRT doses of 48.0 or 54.4 Gy, with 80 mg/m2 of bis-chlorethyl nitrosourea (BCNU) for 3 days every 8 weeks. Distribution of other prognostic factors, including neurologic function, extent of surgery, tumor size, and sex, was comparable in each treatment arm. Results. One Grade 5 radiation therapy (RT)-related toxic effect was reported (in the 54.4-Gy treatment arm), and the incidence of late Grade 3–5 RT-related toxic effects at 18 months was 1% at 48.0 Gy and 4% at 54.4 Gy. The median survival times (MST) for the 48.0 Gy and 54.4 Gy treatment arms were 11.7 and 10.8 months, respectively, comparable to the MST in prior RTOG trials with a similar proportion of patients with glioblastoma multi-forme (79%). For the 123 patients who were 60 years of age or older, the MST for the 48.0 Gy and 54.4 Gy treatment arms were 8.9 and 10.4 months, respectively, and compare favorably with the MST of 6.0 months reported with standard RT and BCNU treatment used for 101 patients who were 60 years of age or older in two prior RTOG malignant glioma trials (74–01 and 79–18). Although these results differ significantly (P < 0.0015), this contrast is not significant when adjusted by performance status. Conclusions. The maximum tolerated dose of AHRT has yet to be identified, and pursuit of this information may most benefit patients with malignant glioma who are 60 years of age or older.

Between January 1983 and November 1987, the Radiation Therapy Oncology Group conducted a prospective, randomized, multi-institutional, dose searching Phase I/II trial to evaluate hyperfractionated radiation therapy in the treatment of supratentorial malignant glioma. Patients with anaplastic astrocytoma, or glioblastoma multiforme, age 18-70 years with a Karnofsky performance status of 40-100 were stratified according to age, Karnofsky performance status, and histology, and were randomized. Initially randomization was to one of three arms: 64.8 Gy, 72.0 Gy, and 76.8 Gy. Fractions of 1.2 Gy were given twice daily, 5 days per week, with intervals of 4 to 8 hr. All patients received bis-chlorethyl nitrosourea (BCNU) 80 mg/m2 on days 3, 4, 5 of radiation therapy and then every 8 weeks for 1 year. After acceptable rates of acute and late effects were found, the randomization was changed to 81.6 Gy and 72.0 Gy with a weighting of 2:1. Out of 466 patients randomized, 435 were analyzed. The distribution of prognostic factors was comparable among the 76.8 Gy arm, 81.6 Gy arm, and the final randomization of the 72 Gy arm. The 64.8 Gy arm and the initial randomization of the 72 Gy arm had somewhat worse prognostic variables. Late radiation toxicity occurred in 1.3-6.8% of the patients, with a modest increase with increasing radiation dose. The best survival occurred in those patients treated with 72 Gy (median survival of 12.8 months overall, and 14 months for the final 72 Gy randomization). The Cox proportional hazards model confirmed the prognostic variables of age, histology and Karnofsky performance status. In addition, the longer interval of 4.5-8 hr was associated with a worse prognosis than the 4-4.4 hr interval (p = 0.0011). The difference in survival between the 81.6 Gy arm and the lower three arms approached significance (p = 0.078) with inferior survival observed in the 81.6 Gy arm. When therapy was evaluated by radiation therapy dose received (60-74.4 Gy compared with 74.5-84.0 Gy), the p value was 0.062 in favor of the lower dose range. Patients with anaplastic astrocytoma treated with 72 Gy by hyperfractionation + BCNU had at least as good a survival as those treated with 60 Gy by conventional fractionation + BCNU on Radiation Therapy Oncology Group protocols 7401 and 7918. This suggests that 72 Gy delivered by 1.2 Gy twice daily is no more toxic than 60 Gy delivered by conventional fractionation.

Fifty-four patients with Grade III or IV malignant glioma were treated with the hypoxic-cell radiosensitizer misonidazole, and radiation therapy (RT) in a Phase II trial of the Radiation Therapy Oncology Group (RTOG). The median survival was 39 weeks. Toxicity was acceptable. Almost all toxicities were reversible and self-limited. The were no significant changes in hematologic, hepatic or renal parameters. The median survival obtained is similar to the results with conventional radiotberapy. A Phase III trial is under way comparing standard radiation and BCNU chemotherapy (1,3-bis (2-chloroethyl)-1-nitrosourea) with sensitized radiation and chemotherapy (RT + misonidazole + BCNU). Additive toxicity between misonidazole and BCNU was not observed in a pilot group.

A randomized prospective study was performed to evaluate misonidazole radiosensitized radiation therapy in the treatment of malignant glioma. The control arm, Group A, consisted of conventional radiation therapy (6000 cGy/6-7 weeks) to the whole brain plus BCNU (80 mg/m2 on day 3, 4, 5, and then repeated q 8 weeks for 2 years). The BCNU schedule was identical in both arms. In the experimental arm, Group B, misonidazole 2.5 gm/m2 was given once a week for six weeks, to a total dose of 15 gm/m2. It was given orally four hours prior to 400 cGy on Mondays. On Tuesdays, Thursdays and Fridays, 150 cGy was delivered to a total of 5100 cGy/6 weeks. An additional 900 cGy/5F/1 week was given without misonidazole. Patients were stratified according to the prognostic factors of age, performance status, and histology. Distribution of these characteristics among the treatment groups was comparable. As of March 1, 1982, 245 patients were randomized with follow-up information available on 202 patients. The median follow-up is 12 months (range 3-39 months). There is no significant difference in the survival of the two groups. The median survival for Group A was 12.6, and for Group B, 10.7 months. Misonidazole toxicity included an 11% peripheral neuropathy and a 3% central nervous system toxicity. BCNU toxicity included severe hematologic toxicity in 25%, including one death, and significant pulmonary toxicity in 6 out of 55 patients who received a minimum total dose of 960 mg/m2 of BCNU.