Psychosocial factors that predict adherence to cancer therapy: Analysis of depression, self-efficacy, and social support

Cancer is a diverse group of diseases, which results from abnormal human gene expression, and when untreated leads to increased mortality. In 2014, over 1.6 million individuals in the United States are projected to receive the diagnosis of cancer. Diagnosis with cancer is a unique stressor, which encompasses biological, psychological, and social challenges. Cancer therapy (i.e., chemotherapy, radiation) requires that the patient engage in significant health behavioral changes and often results in unpleasant and disruptive side effects. Adherence to treatment is a significant and ubiquitous medical problem as well as a complex, multidimensional behavioral change process. Adherence is defined as “the extent to which a person’s actions or behaviors coincide with advice or instruction from a health care provider intended to prevent, monitor, or ameliorate a disorder.” Failure to adhere reasonably well to treatment regimens diminishes the full therapeutic benefit. Given that adherence involves multiple health behaviors and that non-adherence can result in worsening disease or death, the factors that predict likelihood of engaging in adherence behaviors warrant investigation. Overall, patient adherence is theorized to be explained by a combination of factors including: (1) patient attitudes, beliefs, and motivations, (2) mood, (3) perceived self-efficacy, (4) social support factors, (5) medical system factors, and (6) disease-related/treatment related factors. Therefore, adherence behaviors of cancer patients (i.e., medication-taking behavior and appointment attendance) were investigated in terms of the relationship of these behaviors with three of the mentioned theorized psychosocial areas, namely depressed mood, self-efficacy, and social support factors. Simultaneous multiple regression analyses were used to investigate whether depressed mood, self-efficacy for coping with cancer, and functional social support factors predicted the likelihood of patients engaging in each adherence behavior. Overall, of the 100 participants, patients at the Southwest Cancer Treatment and Research Center (SCTRC), most, but not all, patients adhered to prescribed medical therapy and attended the majority of their scheduled appointments. Notably, the results suggest that the simultaneous regression model explained a significant proportion of variance in participants’ self-reported medication taking behavior, R2 = .098, F (3, 93) = 3.36, p = .02. Patients’ depression scores significantly predicted their self-reported medication taking behavior. The other variables in the model, however, did not predict patients’ self-reported medication taking behavior, above and beyond participants’ depression scores. Moreover, the regression model was not significant for predictors of appointment attendance. Given that patients’ with greater depression symptoms were less likely to adhere to medications, assessing and treating depression may be an essential component in interventions to reduce rates of non-adherence and to reduce potential impact on treatment outcomes.