Direct-to-consumer advertising (DTCA) of prescription medications and healthcare facilities has generated much debate over the potential benefits and adverse consequences for the public at large, patients, clinician-patient relationships, and the overall healthcare system. This dissertation is aimed at contributing to this debate through studying the impact of DTCA in the context of cancer treatment. Study 1 assessed the reliability and validity of three candidate measures of patient-reported exposure to cancer-related DTCA across seven criteria. The study found that all three measures performed well in terms of convergent, nomological, discriminant, and face validity. Findings from this study offer support for utilizing these survey measures in future studies targeting cancer patients. Next, Study 2 examined the prevalence and correlates of cancer-related DTCA exposure in a sample of patients in Pennsylvania diagnosed with breast, prostate, or colorectal cancers. On average, patients reported modest exposure to such DTCA (median exposure was once per week). Significant correlates of exposure included cancer type, age, stage of disease, and ethnicity. Study 3 investigated the relationships between DTCA exposure and subsequent information seeking behaviors. The analyses detected a significant association between DTCA exposure and cancer patients' subsequent information engagement with their clinicians at one-year follow-up. Exposure to DTCA was marginally significant in predicting information seeking from non-clinician (lay media and interpersonal) sources. Based on the Integrative Model of Behavioral Prediction, a focused analysis showed a significant indirect path between DTCA exposure and subsequent information seeking from non-clinician sources, mediated through attitudes and intention to seek from these sources. Study 4 was guided by the Structural Influence Model of Communication to explore disparities in health information seeking behaviors arising from DTCA exposure. The study found that the associations between DTCA exposure and active information seeking behaviors were not moderated by patients' age, educational level, race/ethnicity, or cancer type. To conclude, these studies would likely inform the ongoing debate and future research regarding the impact of cancer-related DTCA exposure on communication outcomes and disparities.