Cisplatin, continuous-infusion 5-fluorouracil, and intermediate-dose methotrexate in the treatment of unresectable non-small cell carcinoma of the lung. Forty-one patients with unresectable non-small cell carcinoma of the lung (NSCCL) were treated with cisplatin 20 mg/m2/d for 5 days as a daily bolus injection, 5-fluorouracil 800 mg/m2/d by continuous infusion for 5 days, and intermediate-dose methotrexate 200 mg/m2 on days 15 and 22 of a 28-day cycle (PFM). One complete and 23 partial responses were observed, yielding an overall response rate of 60%. There was no significant difference in response rates based on histologic subtype or extent of disease (locally unresectable versus metastatic). Median duration of response was 6 months, and the median survival of all patients was 10 months. Two patients with unresectable disease at presentation became resectable after chemotherapy and remain disease-free at 46+ and 53+ months. Toxicity was modest, with oral mucositis the major adverse effect. Clinically important neutropenia was uncommon. PFM is an active regimen in NSCCL and deserves further study in the "neoadjuvant" setting. 