Combined modality treatment with chemotherapy and radiation produces tumor regression in most patients with small-cell lung cancer, but the impact on survival has been small, and less than 20% of patients with limited disease survive 2 years. Survival time is extremely short after failure to respond or relapse after treatment. Local control remains a problem, with one third of patients having recurrence only at the primary site. In an attempt to prolong survival and perhaps achieve cure, we undertook surgical resection in 28 patients with limited small-cell lung cancer who did not have complete remission with standard treatment or who had only local recurrence after treatment. There were 28 patients, 22 male and six female, median age 61 years (range 41 to 76). All patients had been treated with chemotherapy and 13 had received preoperative radiotherapy to the primary site and mediastinum. Eight patients underwent an operation for relapse after complete remission. Five patients had had no response to treatment, three had had a slight response followed by progression during chemotherapy, and 12 had achieved partial response but had greater than 3 cm residual masses. Twelve patients required pneumonectomy, 15 lobectomy, one patient had unresectable disease, and two had bulky residual masses after the operation. Three others had microscopic residual disease. Pathologic examination showed only small-cell lung cancer in 18 patients, mixed small-cell and non-small-cell in four, and only non-small-cell lung cancer in six. There were only four patients with stage I disease, 10 with stage II, and 14 with stage III. The median survival from the date of diagnosis for the entire group is 105 weeks and from the date of operation, 74 weeks. The projected 5-year survival rate is 23%. The two patients with residual masses died with local progression, and distant metastatic disease developed in 17 others. One patient died at 6 years without recurrent disease. Eight patients are alive 2 to 5 years after diagnosis. Seven of these patients required only a lobectomy, four had stage I disease, two had stage II, and two had stage III disease. Five had pure small-cell lung cancer and three had mixed small-cell and non-small-cell tumors. All of the patients with pathologic stage I disease remain alive compared with one of 10 with stage II disease and two of 14 with stage III. In summary, relapse or failure to respond to chemotherapy may be due to non-small-cell lung cancer or a mixed tumor.(ABSTRACT TRUNCATED AT 400 WORDS)