Detection of large cell component in small cell lung carcinoma by combined cytologic and histologic examinations and its clinical implication.

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.