Subclassification of small cell cancer of the lung: the Southeastern Cancer Study Group experience

Cancers in more than 300 patients being treated by Southeastern Cancer Study Group protocols for small cell carcinoma of the lung (SCCL) were subclassified as oat cell or intermediate types by criteria developed by two groups of investigators. With Cox survival and logistic regression models, no differences in survival or responsiveness to therapy were found between these types of tumors. These and previously published results suggest that the only intermediate tumors worth distinguishing are the "22/40" tumors with morphologic features precisely intermediate between those of SCCL and non-SCCL, including mildly vesicular nuclei, common small nucleoli, and rims of stained cytoplasm. Such tumors are the dividing point between SCCL and non-SCCL and constitute a small fraction of the spectrum from SCCL to non-SCCL.