The role of histopathologic subtyping in predicting neurologic complications in small-cell lung-cancer

We examined the significance of histologic subtyping of small cell lung cancer (SCLC) as a prognostic factor for neurologic complications and in particular central nervous system (CNS) metastases. Pretreatment material of 239 consecutive patients with SCLC was retrospectively reexamined according to the histologic subclassification of the Pathology Panel of the International Association for the Study of Lung Cancer. Besides the classic small cell type (n=178), this subclassification distinguishes two variant cell types: mixed (n=31) and combined (n=1), which were treated as one group in the further statistical analysis. Twenty nine cases were not classified, for the following reasons: autopsy material only (n=14), slides missing (n=7), and initial SCLC diagnosis changed (n=8). The results showed that neurologic complications registered in a prospective neurologic follow-up were common in both subtypes and predominantly metastatic in nature. The data did not reveal any significant difference between histologic subtypes with regard to CNS metastases and brain metastatic-free survival. Paraneoplastic syndromes tended to occur more frequently in patients with classic small cell type. However, this relationship needs further study. It was concluded that no prognostic relevance exists for histologic subtyping with respect to neurologic complications.