Postoperative adjuvant chemotherapy in non-small cell lung cancer: prognostic value of DNA ploidy and post-recurrent survival. Eighty-six patients with non-small cell lung cancer who underwent curative operations were postoperatively randomized to control and adjuvant chemotherapy groups. In the adjuvant chemotherapy group, patients received cisplatin-based combination chemotherapy 3 or 4 weeks after operation and the average cycle of chemotherapy was 2.3 (from 1 to 6 cycles). In this trial, no evidence of improved survival or delayed recurrence was seen in the treated patients. In multivariate analysis of prognostic variables, the most important factor was the pathological stage of the disease and, second, DNA ploidy of the primary tumor. Although histology (squamous vs. non-squamous cell carcinoma) had a trend to influence the survival, it was not a significant factor. A total of 33 patients had recurrences: 17 and 16 patients were in control and adjuvant chemotherapy groups, respectively. Postrecurrent survival in the adjuvant chemotherapy group was significantly shorter than that in the control group, as determined by the generalized Wilcoxon and log rank tests. Median survival time after recurrence in the control and adjuvant therapy groups was 18.5 and 7.5 months, respectively. These results suggest that DNA ploidy of primary tumors should be considered as a prognostic factor in future trials of adjuvant therapy. Furthermore, analysis of postrecurrent survival in the adjuvant chemotherapy trial, as well as that of overall and disease-free survivals should be done. 