Is there a case for cisplatin in the treatment of small-cell lung cancer? A meta-analysis of randomized trials of a cisplatin-containing regimen versus a regimen without this alkylating agent

Abstract

Chemotherapy is the backbone of small-cell lung cancer therapy. However, optimal drug combinations and schedules remain to be defined and there is hitherto no world-wide accepted standard regimen. Cisplatin, an alkylating agent with high putative toxicity is currently widely used although its effectiveness in this disease has not been established firmly. We conducted a meta-analysis of published data reporting trials randomizing a cisplatin-containing regimen versus a regimen without this alkylating agent in order to determine possible differences in survival response and toxicity. Nineteen trials have been identified in medical literature (4054 evaluable patients). Ten trials randomized patients to receive a cisplatin-etoposide regimen versus a regimen without any of these two drugs. A subgroup analysis was, therefore, carried out in the nine remaining trials that randomly allocated patients between two regimens differing in the absence or presence of cisplatin, whereas etoposide was given (or not given) in both arms (1579 evaluable patients). The DerSimonian and Laird method was used to estimate the size effects and the Peto and Yusuf method was used in order to generate the odds ratios (OR) of reduction in risk of death and the increase in probability of being responders to chemotherapy. There was no significant difference between the cisplatin-containing regimen and the regimen without this drug when the risk of toxic-death was taken into account with respective probabilities of 3.1 and 2.7% (NS). Patients randomized in a cisplatin-containing regimen had an increase in probability of being responders with an OR of 1.35, 95% confidence interval (CI) of 1.18-1.55; P < 10(-5) corresponding to an increase of objective (partial plus complete) response rate from 0.62 to 0.69 (a result taking into account a significant heterogeneity). Patients treated with a cisplatin-containing regimen benefited from a significant reduction of risk of death at 6 months and 1 year with respective OR 0.87, 95% CI 0.75-0.98, P = 0.03, and or 0.80, 95% CI 0.69-0.93, P = 0.002 (no statistical heterogeneity). This corresponded to a significant increase in the probability of survival of 2.6% and 4.4% at 6 months and 1 year respectively. The meta-analysis restricted to the subset of nine trials without etoposide treatment imbalance reached similar conclusions. A cisplatin-containing regimen yields a higher response rate and probability of survival than does a chemotherapy containing others alkylating agents without a perceptible increase in risk of toxic-death.