Background: In the classification recently proposed by the Pathology Committee of International Association for the Study of Lung Cancer, small cell lung carcinoma (SCLC) was divided into three subtypes: pure SCLC, mixed small cell/large cell carcinoma (mixed SC/LC), and combined SCLC.
Methods: To examine the clinical utility of this classification, histologic specimens, cytologic specimens obtained by brushing or fine-needle aspiration, and sputum cytologic specimens from 430 patients with SCLC were reviewed.
Results: When the subtype of SCLC was determined from the biopsy specimen, cytologic specimen obtained by brushing or fine-needle aspiration, and sputum cytologic specimen, the frequency of mixed SC/LC was 25 of 299 (8.4%), 75 of 400 (18.8%), and 8 of 232 (3.4%), respectively. Whatever the diagnostic method, patients with mixed SC/LC showed a poorer response to treatment and worse prognosis than those with pure SCLC: a median survival of 144 days versus 285 days when classified with the use of biopsy specimens; 160 days versus 275 days with cytologic specimens obtained by brushing or fine-needle aspiration; and 47 days versus 259 days with sputum cytologic specimens, respectively.
Conclusions: These findings showed that mixed SC/LC should be separated from pure SCLC as a distinctive group and that cytologic studies of specimens obtained by brushing or fine-needle aspiration were sensitive and useful procedures for this purpose.