PURPOSE/OBJECTIVE: To report on two consecutive Phase II cooperative trials in which we evaluated the combination of alternating hyperfractionated accelerated radiotherapy and cisplatin-based chemotherapy in inoperable Stage III non-small cell lung cancer (NSCLC). PATIENTS & METHODS: Between February 1986 and September 1989, 65 patients were entered in the first trial (GOTHA I), and between December 1989 and October 1992 67 were enrolled in the second trial (GOTHA II). In both protocols, radiotherapy (RT) was administered twice daily, at 6 h intervals, 5 days a week, to a total dose of 63 Gy in 42 fractions of 1.5 Gy. RT was given during weeks 2, 3, 6, and 7, over an elapsed time of 6 weeks. In GOTHA I, three cycles of cisplatin, 60 mg/m2 day 1, mitomycin, 8 mg/m2 day 1, and vindesin 3 mg/m2 day 1 and the first day of the following week, were given during weeks 1, 5, and 9; in GOTHA II, cisplatin 70 mg/m2 day 1 and vinblastin 5 mg/m2 day 1 and the first day of the following week were given during weeks 1, 5, 9, 13, 17, and 21. RESULTS: With a minimum follow-up of 3 years, the 1-, 2-, 5-, and 8-year overall survival probability was 56% (95% CI 47-64%), 27% (20-35%), 12% (7-18%) and 9% (3-16%), respectively, with a median survival of 13.6 months (11.4-16.8). Median follow-up for survivors was 6 years (3.3-9.9). There were no survival differences between Stages IIIA and IIIB (p = 0.84), performance status 0, 1, 2 (p = 0.87), sex (p = 0.45) or between the two treatment protocols. At this time, 14 patients are alive, and 118 have died: 102 from NSCLC, 4 from acute toxicity, 2 from secondary surgery, 4 from other medical causes, and 6 from unknown causes. Correlation between response and long-term survival was poor, since of the 24 patients who survived 3 years or more, only 6 (25%) were classified as having a complete response; the remainder having either a partial response (11, 46%), no change (6, 25 %), or "progressive disease" (1, 4 %). First site of relapse was local in 31% of these cases, distant in 43%, local and distant in 15 %, and unknown in 11%. Main grade 3-4 acute toxicities were nausea-vomiting (17%), mucositis (15%), leukopenia (41%), and thrombocytopenia (11%). Eight patients presented with grade 3-4 symptomatic lung radiation pneumopathy. CONCLUSION: Based on this experience with 132 patients, this combination of alternated RT and chemotherapy (CT) for inoperable Stage III NSCLC is feasible with acceptable toxicity, and long-term results suggest a gain in survival when compared to those obtained with conventional RT alone. However, the still high local and distant failure rates indicate that both local and systemic therapies need to be improved.