The Influence of Neighborhood Socioeconomic Status and Follow-up on Survival in Early-Stage Non-Small Cell Lung Cancer Treated With Stereotactic Ablative Radiotherapy

Abstract

Cancer patients with lower socioeconomic status (SES) have been shown to have worse outcomes, but the influence of neighborhood-level SES has not been well-established. One widely used geographic measure of SES is via a publicly available, U.S. Census-based neighborhood disadvantage metric called the Area Deprivation Index (ADI). We hypothesized that residence in a lower SES neighborhood, as indicated by higher ADI, would be associated with worse progression-free (PFS) and overall survival (OS) in patients with early-stage non-small cell lung cancer (NSCLC) treated with stereotactic ablative radiotherapy (SABR).A retrospective review was conducted using an institutional database containing patient and disease characteristics including race, smoking status, and Charlson Comorbidity Index (CCI) scores. Neighborhood-level factors, such as ADI and rural-urban codes, were incorporated by applying clinical informatics to manage large-scale data. Loss to follow-up was defined as being alive but with no follow-up > 6 months after completing SABR. Kaplan-Meier with log-rank analysis and Cox regression were conducted for PFS and OS, and logistic regression was performed to evaluate for predictors of loss to follow-up. Statistical significance was set at P < 0.05.There were 513 patients treated from 2004-2018 with a median follow-up of 25 months (range: 0-190). Median PFS was 20 months, and median OS was 36 months. The median age was 73 years; 45% were male, 14% were Black, 30% were actively smoking, 74% were from an urban neighborhood. Median SABR dose was 54 Gray in 3 fractions. ADI scores ranged from 21.68 to 156.85 and were normally distributed; the first quintile mean ADI was 71.49 (least disadvantaged) and the fifth quintile mean ADI was 124.97 (most disadvantaged). On Kaplan-Meier (log-rank) analysis, loss to follow-up was associated with worse PFS and OS (P < 0.001). On multivariable analysis, loss to follow-up (HR 12.43, 95% CI: 6.40-24.18) and Black race (HR .59, 95% CI: .36-.98) were associated with improved PFS. For OS, after controlling for other variables, loss to follow-up (HR 5.41, 95% CI: 4.15-7.05), higher ADI (HR 1.01, 95% CI: 1.00-1.02), urban home location (HR 1.56, 95% CI: 1.18-2.05), higher CCI (HR 1.16, 95% CI: 1.08-1.24), and larger tumor size (HR 1.13, 95% CI: 1.01-1.27) were associated with worse OS, whereas female sex (HR .61, 95% CI: .49-.76) and Black race (HR .42, 95% CI: .28-.65) were associated with improved OS. ADI, urban home location, and race were not significant predictors of loss to follow-up.Loss to follow-up, urban home location, and lower socioeconomic status, as represented by higher ADI values, were found to be independently associated with worse OS, suggesting the importance of considering SES and potential barriers to follow-up in patient care.