Factors associated with histologic versus cytologic diagnosis of lung cancer.

Abstract

6048 Background: In the era of molecularly targeted agents, optimal lung cancer treatment decision making requires high quality pathology, including histologic rather than cytologic results. If there are differences in the likelihood of histologic diagnosis by race, ethnicity, or socioeconomic status (SES), it could contribute to disparities in lung cancer treatment and outcomes. Methods: We evaluated the nature of the pathologic diagnosis among 3760 lung cancer patients enrolled in CanCORS (the Cancer Care Outcomes and Research Consortium), a multi-region population- and health system-based prospective cohort study. Patients were diagnosed in 2002-2005. Patients were classified as having a histologic or a cytologic diagnosis, on the basis of procedures performed from 3 months before to 3 months after diagnosis, abstracted from medical records. A multivariable generalized logistic regression model was fitted to evaluate the association of clinical, sociodemographic, and health system factors on type of diagnosis, conditional on patients’ not having primary surgery for lung cancer. Results: Overall, 44% of patients had a procedure yielding histology (30% with primary surgery and 14% without). Race, SES, and gender were not significantly associated with having a histologic diagnosis. Older patients were significantly less likely to have histology (in reference to age < 65: odds ratio [OR] 0.70 (95% CI 0.51-0.96) for age 65-74 and OR 0.65 (95% CI 0.46, 0.91). for age 75+) In a secondary analysis substituting geographic region for data collection site, we found that patients treated in the South and Midwest (compared to the West) and those receiving care in staff model HMOs were more likely to have cytology only. Conclusions: In the first several years after the approval of targeted agents for lung cancer, the majority of patients were not receiving histologic diagnoses. We did not identify disparities in care by race or ethnicity; but other non-clinical factors including region of the country and health system characteristics appeared to play a role. Future studies should consider the quality of the pathologic information in evaluating disparities in lung cancer treatment and outcomes.