BACKGROUNDThe objective of this study was to evaluate the feasibility, toxicity, and efficacy of a novel three‐drug regimen containing paclitaxel, carboplatin, and topotecan followed by oral etoposide in the first‐line treatment of patients with small cell lung carcinoma.METHODSOne hundred five patients with previously untreated, limited stage or extensive stage small cell lung carcinoma were treated in this multicenter, community‐based, Phase II trial. All patients received paclitaxel 135 mg/m2 by 1‐hour intravenous (IV) infusion on Day 1, carboplatin at an area under the serum concentration‐time curve of 5.0 IV on Day 1, and topotecan 0.75 mg/ m2 IV on Days 1–3. The treatment regimen was repeated at 21‐day intervals for 4 courses. Patients with limited stage disease also received radiation therapy (45 grays [Gy]; in single daily fractions of 1.8 Gy) beginning concurrently with the third course of chemotherapy. Patients who had an objective response or stable disease after 4 courses of combined paclitaxel, carboplatin, and topotecan then received 3 courses of oral etoposide (50 mg alternating with 100 mg for 10 consecutive days) repeated at 21‐day intervals.RESULTSTreatment with paclitaxel, carboplatin, and topotecan produced response rates of 88% and 93% in patients with extensive stage disease and limited stage disease, respectively. The median survival for patients with extensive stage and limited stage disease was 8.3 months and 17.2 months, respectively. The addition of oral etoposide was feasible, but there was no suggestion that it prolonged remission. This three‐ drug regimen was associated with acceptable toxicity in patients with a good performance status, although it was tolerated very poorly by patients with an Eastern Cooperative Oncology Group performance status of 2; 5 of 12 patients (42%) had treatment‐related deaths.CONCLUSIONSAlthough this three‐drug regimen was active in the treatment of patients with small cell lung carcinoma, it was more toxic than standard platinum and etoposide regimens and provided no apparent improvement in efficacy. Further investigation of topotecan as a component of first‐line therapy should focus on two‐drug combination regimens in which the topotecan dose can be optimized. Routine use of three‐drug regimens in patients with small cell lung carcinoma should await demonstration of superiority in randomized trials. Cancer 2002;94:2426–33. © 2002 American Cancer Society.DOI 10.1002/cncr.10508