Monash Health, Berwick, VIC, Australia
Liang G Qu , J. Bailey Vaselkiv , Marlon Perera , Lorelei A Mucci
Background: It is unknown if the impact of rural versus urban settings may impact outcomes in men with metastatic prostate cancer, and in particular survival. This study aimed to examine differences in survival for patients in the United States with de novo metastatic prostate cancer, according to urban-rural status. Methods: This retrospective cohort study utilised data from the publicly available Surveillance, Epidemiology, and End Results database. Data on demographics, urban-rural status, histopathology, and survival were extracted for men aged 18-75 diagnosed with metastatic prostate cancer between 2009-2018. Rurality was re-classified from the rural-urban continuum code which ranged from 1 (most urban) to 9 (most rural). Individuals missing rurality status or survival-related data were excluded. Overall and cancer-specific survival between individuals living in urban and rural settings were analysed using multivariable Cox regression and adjusted restricted mean survival time modelling. Subgroup analyses were performed for histological subtypes of prostate cancer. Sensitivity analyses were performed using varying definitions of rurality. Results: Altogether, 21,291 individuals were included, with 2,510 living in rural settings, defined as rural-urban continuum code ≥ 4. The rural and urban participants differed in age, race, U.S. region, and marital status. There was no association between urban-rural status and overall survival (adjusted hazard ratio [HR] = 1.03, 95% confidence interval [CI]: 0.97-1.09, 11,333 events) or cancer-specific survival (1.03, 0.97-1.10, 9,380 events) using Cox regression models. Adjusted restricted mean survival time modelling demonstrated that urban patients lived 2.29 months longer than rural patients (95% CI: 0.61-3.97). Sub-analyses of neuroendocrine, intraductal, and other histological subtypes did not show an association between urban-rural status and overall survival. A more selective definition of rurality (rural-urban continuum code ≥ 5) resulted in a persisting difference in overall mean survival time (2.12 months, 0.24-4.01) using restricted mean survival time modelling. Similarly, a broader definition of rurality (rural-urban continuum code ≥ 3) also resulted in a difference in overall mean survival time (1.98 months, 0.59-3.36). Conclusions: This retrospective analysis demonstrated that a U.S. individual with metastatic prostate cancer who resided rurally died sooner compared to those from urban areas, suggesting greater disease impact in rural settings.
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