Abstract PD6-06: PD6-06 Racial and ethnic disparities with influenza vaccine use in long-term survivors of metastatic breast cancer
Authors: Doshi Sahil D. , DeStephano David , Accordino Melissa K. , Elkin Elena B. , Wright Jason D. , Hershman Dawn 
Published: March 2023

Abstract
Background: Due to therapeutic advancements, people diagnosed with metastatic breast cancer (MBC) are living longer. This is particularly true for elderly patients who are often diagnosed with more indolent disease. However, elderly patients have higher rates of comorbidity and are vulnerable to other adverse health outcomes, but the primary care management of patients with advanced cancer may be sub-optimal. Every year influenza results in hundreds of thousands of hospitalizations and tens of thousands of deaths. Guidelines recommend the influenza vaccine annually for those over the age of 65 as well as those with cancer based on studies showing a 40-60% reduction in hospitalizations and death. Patterns of use in patients with MBC is unknown. Methods: A retrospective analysis was conducted using the Surveillance, Epidemiology, and End Results (SEER)–Medicare linked data. Patients were included if they were diagnosed with stage IV MBC from 1/1/2008 – 12/31/2017, were ≥65 years of age, and had continuous Medicare enrollment for 12 months prior to diagnosis and at least three months after. Our primary outcome of interest was influenza vaccine use identified via CPT codes and defined as any use, use among patients surviving &gt; 3-years, use among patients surviving &gt;5-years, and repeated vaccine use. We then conducted bivariate analyses using demographic variables, including race, ethnicity, SES, age, and marital status, and clinical factors, including chemotherapy use, ER/PR positivity, and HER2 positivity. A multivariable logistic model was used to identify factors associated with influenza vaccine use in each cohort. Results: We identified 5182 patients with stage IV MBC during the study period that met our inclusion criteria. Overall, the median survival was 21 months and only 44% received at least one vaccination at any time after diagnosis. Within the cohort with the &gt; 3-year survival (n=1864), only 1222 (66%) received an influenza vaccination at least one time and only 54% received the vaccine at least two times during 3 years of follow-up. Among patients with at least five-years of survival (n=763), 73% received at least one vaccination and only 65% received the vaccine at least two times during 5 years of follow-up. In a bivariate analysis in the 3-year survival cohort, we found that black race (47% vs 67%, p&lt; 0.001) and Hispanic ethnicity (53% vs 66%, p=0.026), compared to white race and non-Hispanic ethnicity, respectively, were significantly associated with decreased vaccine use. The only factor associated with increased use was chemotherapy exposure. A multivariable model found lower odds of influenza vaccine receipt for black patients (OR=0.44, 95% CI 0.30-0.65, p&lt; 0.001) and Hispanic patients (OR=0.58, 95% CI 0.36-.94, p=0.026). Similar findings were found in the 5-year survival cohort. Ongoing landmark analyses will be presented evaluating the impact of vaccination on survival. Conclusions: Over 50% of survivors with MBC do not receive the influenza vaccine after diagnosis. Importantly black and Hispanic patients with MBC are about half as likely to receive the influenza vaccine as white patients. Given the known impact of influenza vaccination in the elderly, improving access to vaccination could be an important strategy to reduce disparities in health outcomes. Our findings demonstrate primary care access disparities amongst the MBC population and indicate a need for educational and policy-based interventions.
Citation Format: Sahil D. Doshi, David DeStephano, Melissa K. Accordino, Elena B. Elkin, Jason D. Wright, Dawn Hershman. PD6-06 Racial and ethnic disparities with influenza vaccine use in long-term survivors of metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD6-06.