Influenza vaccination in elderly patients with advanced colorectal cancer

Purpose: To examine influenza vaccination use in patients undergoing chemotherapy for advanced cancer. Methods: All Medicare patients treated for stage IV colorectal cancer between 1993 and 1998 while living in one of the regions monitored by the Survival, Epidemiology, and End Results Program who were alive in the fall months and who survived at least 4 months with their cancer were considered eligible to have received vaccination. Their medical bills were analyzed to determine receipt of influenza vaccination and subsequent outcomes. Results: Eligibility criteria were met by 1,225 patients who were undergoing chemotherapy during 1,577 person-years of observation. Overall, 39.7% of patients received influenza vaccination, increasing from 26% in 1993 to 43% in 1998. When vaccination was administered, it was provided by primary care physicians 68% of the time. Vaccinated patients were more likely to be white, of higher socioeconomic status, and to have more comorbidity. Fewer diagnoses of influenza and pneumonia infections were made in vaccinated patients while undergoing treatment. Those patients who were immunized also had fewer chemotherapy interruptions and were more likely to survive through to the beginning of the next fall (hazard ratio, 0.88; 95% confidence interval, 0.77 to 0.99). There was a trend toward decreased resource use among immunized patients. Conclusion: This study observed outcomes associated with influenza vaccination that are similar to those reported for patients without cancer. However, rates of immunization are relatively low, and disparities exist for vulnerable populations. As part of delivering high-quality care, oncologists should promote influenza vaccination for their patients who are undergoing treatment for advanced cancer.