Measurable or assessable disease in lung cancer trials: does it matter?

The goals of this study were to analyze and compare the major clinical response rates and survival of patients with either measurable or assessable disease status to treatment with systemic chemotherapy.

All patients had stage IIIB or IV non-small-cell lung cancer (NSCLC) and were enrolled onto three consecutive phase III clinical trials. Patients were stratified by disease status (measurable or assessable) before randomization to systemic chemotherapy. The three trials were conducted in the setting of a multicenter cooperative oncology group. Composite data were obtained for the three trials. Major clinical responses, time to progression, and survival were analyzed and compared in patients with measurable or assessable disease using standard statistical methods.

Four hundred twenty-six patients were enrolled onto the three trials from June 1981 through August 1990. Measurable disease was present in 236 patients (55%) and assessable disease in 190 (45%). Each study was well balanced for the number of patients with measurable or assessable disease on either treatment regimen. A major clinical response was observed in 71 patients with measurable disease (30%; 95% confidence interval [CI], 24 to 36). Forty patients with assessable disease responded to treatment (21%; 95% CI, 16 to 28) (P = .04). The time to progression for all patients (P = .23) and for responders only (P = .10) was not significantly different based on disease status. Overall survival and survival of responders only was not significantly different, but patients with assessable disease tended to do better. Using multivariate analysis, sex and disease status had a borderline influence on the major response rate (P = .05). Performance score (PS) was the only factor that was significantly correlated with survival.

NSCLC patients with assessable disease have major clinical response rates, time to progression, and survival that are similar to those of NSCLC patients with measurable disease. This study supports the inclusion of patients with assessable-disease lung cancer in both phase II and III trials conducted in the cooperative group setting.