Evaluation of response criteria in advanced lung cancer.

Because we found it illogical to attempt measurement of nonmeasurable but visible tumors in patients with advanced lung cancer, we devised and used a separate set of response criteria for patients with evaluable, nonmeasurable tumors. Patients with evaluable disease who had obtained a tumor regression after therapy were compared to patients with measurable disease who had obtained a tumor regression according to standard criteria. Among 191 cases evaluated (54% with measurable and 46% with evaluable disease), 59 tumor regressions were found (35 in patients with measurable disease and 24 in patients with evaluable disease). Evaluating regressions in patients with both types of disease, we could not detect statistical differences in regression rates, times to regression, durations of regression or survival. We believe the response criteria used for patients with evaluable, nonmeasurable lung cancer to be valid in assessing response to therapy.