A prospective randomized study of various irradiation doses and fractionation schedules in the treatment of inoperable non-oat-cell carcinoma of the lung. Preliminary report by the radiation therapy oncology group

Abstract

Preliminary analysis is presented of a prospective randomized study involving 365 patients with histologically proven unresectable non-oat-cell carcinoma of the lung treated with definitive radiotherapy. The patients were randomized to one of four treatment regimens: 4000 rad split course (2000 rad in five fractions one week, two weeks rest, and an additional 2000 rad in five fractions in one week) or 4000, 5000, or 6000-rad continuous courses in five fractions per week. Ninety to 100 patients were accessioned to each group. The one-year survival rate is 50% and the two-year survival rate, 25%. The patients treated with the split course have the lowest survival rate (10% at two years) in comparison with the other groups (range = 20–25%). The complete and partial local regression of tumor was 49% in patients treated with 4000 rad and 55% in the groups treated with 5000 and 6000 rad. For patients who achieved complete regression of the tumor following irradiation, the two-year survival rate is 40%, in contrast to 20% for those with partial regression, and no survivors among the patients with stable or progressive disease. The incidence of intrathoracic recurrence was 33% for patients treated with 6000 rad, 39% for those receiving 5000 rad, and 44–49% for those treated with a 4000-rad split or continuous course. At present, the data strongly suggest that patients treated with 5000 or 6000 rad have a better response, tumor control, and survival rate than those receiving lower doses. However, additional followup of patients at risk in each group will be necessary before a final conclusion is drawn. Patients with high performance status (Kornofsky index higher than 70), or with tumors in earlier stages (T1N2 or T3N0) have a two-year survival rate of approximately 40%, in comparison with 20% for other patients. The various irradiation regimens have been well tolerated, with complications being slightly higher in the 4000-rad split course group (10 severe and 2 life-threatening) and in the 6000-rad continuous course group (9 severe and 4 life-threatening). The most frequent complications have been pneumonitis, pulmonary fibrosis, and dysphagia due to transient esophagitis. Further investigation will be necessary before the optimal management of patients with bronchogenic carcinoma by irradiation is established.