OBJECTIVES:

Diagnosis of NSCLC has improved substantially over the years, accompanied by advances in treatment options. The diagnostic staging criteria for lung cancer is being continuously updated by the American Joint Committee on Cancer. The primary aim is to study variation in distribution of histologic stage at time of diagnosis of NSCLC during 2004-2015. The secondary aim is to quantify the magnitude of geographical variation in survival post-diagnosis in patients with stage IIIB/IV NSCLC.

METHODS:

The Surveillance, Epidemiology, and End Results(SEER) registry data was used. Patients diagnosed with NSCLC during 2004-2015 as the only cancer were included. NSCLC was identified using the International Classification of Diseases for Oncology third edition codes. Registries were categorized as: West, South, Midwest or Northeast regions as per the US Census. Survival analysis using Cox-proportional hazards regression was performed on a sub-cohort of patients with stages IIIB/IV. Patients who died of other causes or were alive/lost-to-follow-up were censored. The proportional hazards assumption was checked for the main explanatory variable (region) using Schoenfeld’s test and the hazard were found to be proportional.

RESULTS:

Among the 310,509 patients diagnosed with NSCLC, there were: 46.2% female, 80.2% white, 28.1% from the South and 61.4% stage IIIB/IV patients. The diagnosis of stage IA and IB increased from 15.6% in 2004 to 23.6% in 2015, unknown stage cases reduced from 9.4% in 2004 to 2.2% in 2015. Survival analysis performed on the sub-cohort showed that patients in the Northeast region had a 7.5%(HR=0.925,p<0.0001) lower risk of cancer-related death compared to those from the South, adjusted for socio-demographic and clinical variables.

CONCLUSIONS:

Geography plays an important role in the survival of NSCLC patients; however, SEER does not give access to chemotherapy treatment variables. Thus, the next step will be to utilize SEER-Medicare Part D linkage to study geographic differences in NSCLC treatment patterns.