Socio-economic status and social isolation as determinants of survival in non-small cell lung cancer

B63

In the USA, African Americans have a higher burden of certain cancers and tend to have poorer outcomes. We hypothesized that the observed disparity by ethnicity in outcomes of patients diagnosed with non-small cell lung cancer could be explained by socio-economic differences between ethnic groups.
 To identify the possible causes of these disparities we studied a cohort of 367 non-small cell lung cancer (NSCLC) patients diagnosed in a tertiary institution in a Metropolitan area in the State of Maryland from January 1st, 1990 to December 31st, 1992 67.6 % of the patients were white Caucasians and 32.4% were African American. Based on the median incomes of their census tract of residence, 89 patients were classified as low income and 278 as higher income. Survival analysis, chi-squared tests and Cox-regression were used to study the effects of socio-economic status (SES), marital status, and racial composition of census tracts on survival.
 Among Stage I patients, 5 year survival for married patients was 55% compared to 25% for patients who were not married (p-value = 0.003). African Americans were 2.3 times more likely to be unmarried compared with Caucasians this difference was significant (p-value < 0.001). After adjusting for potential confounders using Cox proportional hazards regression the most important predictors of survival were marital status, stage at diagnosis, residence in a neighborhood with > 85% African American residents, squamous histology, smoking history and residence in a low income census tract. Patients who were married had a significantly better survival than unmarried patients, harzard ratio was 0.29 (p-value < 0.001). Residents of highly segregated census tracts, i.e. areas with > 85% African Americans; were 71% more likely to die within 5 years of a NSCLC diagnosis. African American heritage was not found to be significantly associated with excess mortality after a NSCLC diagnosis.
 The results of our bi-racial cohort indicated that residents of highly segregated minority neighborhoods had an increased risk of death compared to all other patients. Unmarried patients also had a significantly increased risk of death after a NSCLC diagnosis. This suggests that some of the contributing factors to the disparities in NSCLC survival by ethnicity and income may be due to relative social isolation and residence in highly segregated minority meighborhoods.