Second-line chemotherapy for small-cell lung cancer (SCLC)

Although small-cell lung cancer (SCLC) generally shows an excellent response to initial chemotherapy, most patients finally relapse and salvage chemotherapy is considered. Usually, the response to salvage chemotherapy significantly differs between sensitive and refractory relapse. Sensitive relapse is relatively chemosensitive and re-challenge with the same drugs as used in the initial chemotherapy has been used historically, while refractory relapse is extremely chemo-resistant and its prognosis has been abysmal. To date, a number of clinical trials have been carried out for relapsed SCLC; however, the number of randomized trials is quite limited. At present, topotecan is the only drug approved by the US Food and Drug Administration for relapsed SCLC, and is considered the standard second-line chemotherapy in many countries. More recently, amrubicin has also shown more favorable antitumor activity, and is the most promising at present. Unfortunately, targeted agents have failed to demonstrate effectiveness for SCLC. Better understanding of the molecular mechanisms is clearly needed.