Prognostic factors in small cell lung cancer: Multivariate model based on 778 patients treated with chemotherapy with or without irradiation

The relationships between prognostic factors and duration of survival in small cell lung cancer were investigated in a consecutive series of 874 patients treated with combination chemotherapy with or without irradiation. The series included 443 patients with limited and 431 patients with extensive stage disease based on staging including bone marrow examination and peritoneoscopy with liver biopsy but no routine scans. The median durations of survival for the two disease categories were 48 and 30 weeks, respectively. The influence on survival of various pretreatment factors was investigated by use of univariate methods and Cox’s multivariate regression model. Patients in each stage were treated according to one of three controlled trials. Variations among the applied treatment regimens did not result in significant differences in duration of survival among patients with limited disease. An alternating regimen was superior to continuous therapy in patients with extensive disease and raised serum lactate dehydrogenase. Prognosis was correlated with disease extent. Surgical resection as well as limited stage disease thus both contributed to survival. Poor performance status, reduced hemoglobin concentration, and raised values for serum lactate dehydrogenase were significantly associated with a reduced duration of survival in both stages. Females with limited disease lived significantly longer than males while advanced age was a negative prognostic factor in extensive disease. Plasma sodium and serum urate were both predictive of survival in limited disease. Proved metastatic disease affecting specific sites or total number of metastatic sites did not carry significant prognostic information in a model including a general variable characterizing stage of disease. Fifty of the 778 patients, on whom the multiple regression model was based, were alive and disease free 2 years after the start of the treatment. Two-year survival rates were strongly correlated to groupings based on prognostic factors, and information about disease extent was not mandatory for predicting the probability of long term disease-free survival.