Patterns of tumor recurrence after definitive irradiation for inoperable non-oat cell carcinoma of the lung.

Abstract

<h2>Abstract</h2> Preliminary analysis was carried out on a prospective randomized cooperative group study involving 375 patients with histologically proven unresectable non-oat cell carcinoma of the lung who were 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, five fractions in one week) or 4000, 5000 or 6000 rad continuous courses, five fractions per week. 84 to 100 patients were accessioned to each group. The one year survival rate was about 40%; the two year survival rate was 10% to 18%. The patients who were treated with the split course had the lowest survival (10% at two years) compared with the other groups (14% to 18%). Complete and partial local tumor regression was 48 % in patients who were treated with 4000 rad, 65 % in the 5000 rad and 61 % in the 6000 rad group. The rate of initial intrathoracic recurrence was 38 % in patients who were treated with 6000 rad; 45 % in those who received 5000 rad, 51 % and 64 % with 4000 rad split or continuous course, respectively. Patients who showed complete or partial regression of the tumor following irradiation exhibited an initial local recurrence rate of 42 % and 46 % respectively in contrast to 57 % for those without tumor regression. Patients with epidermoid carcinoma had an initial local failure rate of 53%, adenocarcinoma and large cell undifferentiated carcinoma 41 %. Distant metastases concurrent with or prior to intrathoracic failure were significantly higher in the patients with adenocarcinoma or large cell adenocarcinoma (63%) than in epidermoid carcinoma (33%). The present data strongly suggest that patients who were treated with 5000 or 6000 rad had a better response, tumor control and survival than those who were treated with lower doses. Additional follow-up of patients at risk in each group will be necessary before a final conclusion is drawn. Further investigations should determine the impact that a variety of prognostic factors may have in efficacy of irradiation in patients with bronchogenic carcinoma. This information will be extremely useful in the design of future therapy for these various subpopulations of patients with different manifestations of the disease.