Abstract PO-220: Associations of timing of Medicaid enrollment with stage at diagnosis, treatment delays, and mortality in women with breast cancer
Authors: Xie Evaline , Colditz Graham A. , Lian Min , Greever-Rice Tracy , Schmaltz Chester , Lucht Jill , Liu Ying 
Published: January 2022

Patients insured by Medicaid present with more late-stage breast cancer and poorer survival than privately insured patients. Delayed coverage may contribute to these disparities, since, in many states, diagnoses of cancer and other illnesses influence Medicaid eligibility. Prior studies have linked post-diagnosis Medicaid coverage with lower rates of screening mammography and greater risk of late-stage cancer, but less is known about its impacts on risks of breast cancer treatment delays and mortality. In this study, we examined the relations of timing of Medicaid enrollment in Missouri to breast cancer stage at diagnosis, treatment delays, and mortality. Using Medicaid administrative claims linked to the Missouri Cancer Registry, we identified 4,583 women ages 18 to 65 who were enrolled in Medicaid and diagnosed with breast cancer between 2007 and 2016. We used logistic regression to estimate the odds ratio (OR) of late-stage diagnosis for pre-diagnosis (≥30 days before diagnosis) versus post-diagnosis (within 30 days before diagnosis or later) enrollment, adjusting for age, race/ethnicity, marital status, and ten census tract-level socioeconomic variables. We performed similar regression to analyze odds of treatment delay, further adjusting for tumor characteristics. Cox proportional hazards models were used to estimate the hazard ratio (HR) of breast cancer-specific mortality for pre- versus post-diagnosis enrollment, sequentially adjusting for sociodemographic factors, tumor characteristics, and treatment. Timing of Medicaid enrollment was also defined using two other cutoffs, 90 days and 1 year. Patients enrolled in Medicaid ≥30 days before diagnosis were significantly less likely to be diagnosed at a late stage compared to those who enrolled in Medicaid after diagnosis (OR=0.69, 95% CI=0.60-0.79). This result persisted using 90-day (OR=0.64, 95% CI=0.56-0.74) and 1-year thresholds (OR=0.55, 95% CI=0.47-0.65). We did not observe any significant difference in the likelihood of treatment delays between the two groups using the 30-day (OR=0.93, 95% CI=0.80-1.10), 90-day (OR=1.00, 95% CI=0.85-1.18) or 1-year thresholds (OR=0.93, 95% CI=0.77-1.12). After adjustment for sociodemographic factors, there was no significant difference in the risk of breast cancer mortality for patients enrolled in Medicaid ≥30 days pre-diagnosis relative to patients enrolled post-diagnosis (HR=0.98, 95% CI=0.83-1.14). The same model, however, showed a lower risk of mortality for patients enrolled in Medicaid before diagnosis when using 90 days (HR=0.85, 95% CI=0.72-0.999) or 1 year (HR=0.79, 95% CI=0.66-0.96) as the threshold. These findings suggest that women who enroll in Medicaid earlier may benefit from earlier diagnoses, but only longer-term enrollment may have survival benefits. Timing of Medicaid enrollment does not appear to play a role in timely initiation of breast cancer treatment.

Citation Format: Evaline Xie, Graham A. Colditz, Min Lian, Tracy Greever-Rice, Chester Schmaltz, Jill Lucht, Ying Liu. Associations of timing of Medicaid enrollment with stage at diagnosis, treatment delays, and mortality in women with breast cancer [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-220.