Combined Small Cell Carcinoma of the Lung: Is It a Single Entity?

We identified no significant clinical or pathologic differences between pure SCLC and CSCLC; CSCLC was associated with decreased overall survival compared with pure SCLC. The histologic components of CSCLC had high genetic concordance but also showed divergent genotypes. These findings may suggest a common precursor with subsequent acquisition of oncogenic changes in CSCLC.