Examining the “Medicare Effect” on Distant-Stage Cancer Diagnoses by Site, Gender, and Rurality

Abstract

Background: Compared to cancers detected early, distant stage cancers are associated with lower survival, diminished quality of life, and higher costs. Evidence suggests that greater access to comprehensive health insurance (i.e., Medicare) improved early detection. Yet, few studies have evaluated the effect of Medicare coverage across cancers or factors influencing healthcare use. Methods: This study analyzed 35 years of population-based cancer registry data from the Surveillance Epidemiology and End Results program for eight common cancers: Oral, Digestive, Respiratory, Skin, Genital, Urinary, Endocrine, and Breast. Leveraging the subjective threshold determining Medicare’s eligibility at age 65, Medicare’s effect on the probability of a distant diagnosis was estimated using Robust Non-Parametric Regression Discontinuity models. Results: Medicare was associated with reduced proportion of distant diagnoses for five common cancers. The proportion of distant cancers declined by 1.7-percentage points for digestive cancers (p < 0.01), 1.6-percentage points for respiratory cancers (p < 0.01), 0.5-percentage points for genital cancers (p < 0.05), 1.4-percentage points for urinary cancers (p < 0.01), and 0.8-percentage points for female breast cancers (p < 0.01). The relative difference from average distant stage rates for these significant estimates range from 3% (Respiratory) to 15% (Genital). Most estimates were consistent across gender, but Medicare was only associated with declined distant-stage diagnoses for patients in urban and metro regions. Conclusions: This study reaffirms that Medicare coverage is associated with earlier diagnoses for patients in urban and metro regions for digestive, respiratory, genital, urinary, and female breast cancers. These results stress the importance of healthcare insurance, but also reveal the limitations of insurance expansion policies for patients in rural areas and for cancers without standard screening protocols.