Frequency of carcinoma not otherwise specified (NOS) as a histologic diagnosis among non-small cell lung cancer (NSCLC) cases between 1989 to 2006: An epidemiologic study from the California Cancer Registry

Abstract

e19049 Background: Recent clinical trials demonstrated differential survival benefit from different chemotherapy regimens according to NSCLC histologies. We investigated the distribution of carcinoma NOS (not otherwise specified) among NSCLC cases in California. Methods: Retrospective population-based analysis of 175,298 NSCLC patients diagnosed histologically or cytologically from the statewide California Cancer Registry from 1989 to 2006. Results: Carcinoma NOS accounted for 22.2% of all NSCLC patients, was most commonly diagnosed cytologically (36.7%) and had the worst 5-year survival estimates (5.8%) and median OS (5 months) compared to other major histologies. The proportion of carcinoma NOS was highest among stage 4 disease and increased significantly from 1989 to 2006 among all patients, both males and females, all 4 major ethnicities (Caucasian, African-American, Hispanic, and Asian), all age- categories, and all AJCC stages. The percentage of the very elderly (80+) increased from 10.8% to 17.1% among all NSCLC patients and they had the highest percentages of carcinoma NOS and cytologically-diagnosed NSCLC among all age categories. Among stage 4 patients, carcinoma NOS patients derived less survival benefit from chemotherapy than adenocarcinoma patients during the most recent period of diagnosis and Cox proportional hazards analysis indicated carcinoma NOS (vs. adenocarcinoma; HR = 1.061, 95% CI: 1.040- 1.083) and cytologically-diagnosed NSCLC (vs. histologically-diagnosed NSCLC, HR = 1.043, 95% CI: 1.024–1.062) were independent unfavorable prognostic factors for OS. Conclusions: Carcinoma NOS was a common histologic diagnosis and was increasing in proportion among NSCLC in California from 1989 to 2006. This may be partially attributed to the increasing number of the very elderly patients and stage 4 patients. No significant financial relationships to disclose.