Topotecan in the treatment of relapsed small cell lung cancer.

Small cell lung cancer (SCLC) represents about 15% to 20% of all lung cancers. Chemotherapy is the cornerstone of the treatment, cisplatin-etoposide combination being the most used combination as first-line therapy. Despite high initial chemosensitivity, most SCLC patients will experience relapse sooner or later. Unfortunately, second-line chemotherapy does not result in a high response rate like first-line therapy, most patients having developed wide chemoresistance. This chemoresistance is far more important in refractory patients, ie, those who never responded to first-line therapy or who relapsed within 3 months after the end of chemotherapy, than in sensitive patients, ie, those who relapse more than 3 months after the end of chemotherapy. Topotecan, a topoisomerase I inhibitor, is the most studied drug in this second-line setting and has proved its efficacy as a single agent and in combination. A phase III trial comparing oral topotecan to best supportive care (BSC) in relapsed SCLC demonstrated a significant survival benefit as well as a better quality of life. Although the usual schedule is 1.5 mg/m(2), days 1-5 intravenously, it is not convenient for patients with relapsed SCLC, especially those who are refractory because of their short survival expectation. Oral topotecan is of similar efficacy and much more convenient with limited stay in a treatment unit and has a comparable toxicity profile for these patients with short expected survival. Combination of topotecan with platinum salts or taxanes does not seem to improve further the outcome of the patients and thus single-agent therapy with topotecan is the standard treatment for relapsed SCLC.