Abstract
Introduction: Cancer and diabetes mellitus (DM) are leading causes of death in the United States. Each year, over 245,000 women are diagnosed with breast cancer, and approximately 18% of patients diagnosed have preexisting DM. The presence of a comorbidity, such as DM increases women’s mortality risk by 40%. While studies have shown decreased adherence to hypoglycemic medications after cancer diagnosis, the effect of cancer related beliefs on DM medication adherence has not been fully explored. In this study, we evaluated the association between cancer related beliefs and DM medication adherence in survivors of breast cancer. Hypothesis: Patients with greater positive beliefs about cancer (including personal control, treatment control and understanding) would exhibit greater adherence to DM medication. Methodology: We enrolled women >55 years with Stage 0-IIIA breast cancer diagnosed in the past 10 years, who had completed chemotherapy and/or were prescribed hormonal therapy and had pre-existing type 2 DM treated with at least 1 oral DM medication. Cancer related beliefs were assessed using the Illness Perception Questionnaire (IPQ). Medication adherence was evaluated using the Medication Adherence Rating Scale (MARS). Adherence was dichotomized at a mean MARS score of ≥4.5. Wilcoxon rank-sum tests were used to examine the relationship between patients’ cancer related beliefs and DM medication adherence. Results: Thus far, 108 women have completed baseline surveys. Of these participants, 37% were black, 31% white, 14% Hispanic, 6.5% Asian, and 8.3% other. The mean age was 65 years. Cancer survivors who were adherent to DM medication had a greater sense of personal control over their cancer (median score 22.0 vs. 19.0, p<0.001) and endorsed a better understanding of their cancer (median score 20.0 vs. 14.0, p=0.03). No associations were seen between beliefs about the duration and consequences of cancer and DM medication adherence. Conclusion: Among breast cancer survivors with comorbid DM, having a greater sense of control over and understanding of cancer was associated with DM medication adherence. Working with breast cancer survivors to increase their perceived control over and understanding of their cancer may help improve adherence to DM medication.