Prognostic factors in small cell carcinoma of the lung: a cancer and leukemia group B study

Prognostic factors were studied in 224 patients with small cell carcinoma of the lung entered in a Cancer and Leukemia Group B protocol. Extent of disease was the major predictor of complete remission (CR) frequency and survival greater than 2 years, with CR rates being 40% for patients with limited disease (LD) and 10% for those with extensive disease. Patients who were classified as having extensive disease on the basis of isotope scan evidence of a single bone metastasis had survival characteristics and response rates similar to those of patient with LD. A multivariate analysis of various factors, which may influence overall survival, reveals a good-risk population to be defined as having LD and an initial performance status less than or equal to 2, with or without a single metastatic focus on bone scan. Furthermore, this risk definition fairly successfully predicted which patients had the greatest chance of achieving a CR (45%). Age less than 70 years was shown to be a significantly adverse factor on survival in these multivariate analyses after adjusting for risk. When long-term survivors (less than 24 months) were investigated by multivariate analyses, the new risk system was found to be the only significant pretreatment factor. Interestingly, sex was the next marginally influential factor on long-term survival. Future stratification by these risk categories should lead to more homogeneous subgroups for comparison of different therapeutic approaches and should provide some indication as to how much better the newer treatment program is within each risk group.