Maintenance chemotherapy for small cell lung cancer: a critical review of the literature.

Maintenance chemotherapy after induction therapy is a controversial topic in small cell lung cancer. We carried out a critical review of the literature on this topic. Since 1980, 13 randomized trials have been published. One shows a statistically significant difference in survival in favor of maintenance, five obtain some survival advantages in subgroups of patients, one shows a significantly shorter survival with maintenance and in six studies, there is no difference between both arms. A quantitative overview or meta-analysis was unpracticable because of the lack of data for calculation of the odds ratio in the publications and because of the heterogeneity of the studies' designs. A qualitative overview was carried out using two scales: the Chalmers scores and the European Lung Cancer Working Party (ELCWP) score. Correlation between both scores was excellent. There was no significant difference in quality scores with both methods between negative trials and those who showed some survival advantage for survival. The overall quality of the publications was not good, with important methodological aspects missing, such as a clear definition of the primary objective or an a priori estimate of the sample size necessary to conduct the trial. We concluded that maintenance chemotherapy could have some indications and that good quality trials, as reflected by very high quality scores, need to be carried out in the future.