HISTOLOGIC-CHANGES IN SMALL-CELL LUNG-CARCINOMA AFTER TREATMENT

BACKGROUND. Small cell lung carcinoma (SCLC) has been divided into thr ee subtypes: pure SCLC, mixed small cell/large cell carcinoma (mixed S C/LC), and combined SCLC. Patients with mixed SC/LC show a worse progn osis than those with pure SCLC. METHODS. Persistence of histologic sub type in SCLC in tile primary sites during the course of treatment or i n the different organs at autopsy was examined. For this purpose, biop sy or cytologic specimens before chemotherapy, and autopsy specimens f rom 175 patients with SCLC were reviewed. They included 147 (84%) men and 28 (16%) women with an age range of 29-83 (median, 65) years. RESU LTS. The frequency of mixed SC/LC in the primary sites was statistical ly higher in autopsy (14.3%) than that in biopsy or cytology specimens (8.6%) (P < 0.05). At autopsy, involved organs were categorized into two groups according to frequency of appearance of mixed SC/LC, i.e., a higher frequency group, including the liver (31 of 85; 36.4%), adren al gland (15 of 56; 26.8%), brain (6 of 9; 66.7%), and extrathoracic l ymph nodes (17 of 59; 28.8%) and a lower frequency group, including th e lung (metastatic sites) (12 of 102; 11.8%), pleura (8 of 74; 10.8%), and intrathoracic lymph nodes (12 of 94; 12.8%). The difference in fr equency between these two groups was statistically significant (P < 0. 05). CONCLUSIONS. These findings suggest that primary pure SCLC can pr ogress to mixed SC/LC with an increased potential for distant metastas is. Cancer 1996; 77:278-83. (C) 1996 American Cancer Society.