Project Summary This application is being submitted in response to the Notice of Special Interest (NOSI) identified as NOT-CA- 21-055. The costs associated with cancer and its treatment may have a tremendous impact on patients’ ability to pay for health insurance, health needs, and basic needs (e.g., food, housing, shelter). Given the variation in health insurance coverage, its ability to offset OOP costs, and individuals’ ability to change insurance, insurance coverage is a modifiable factor relevant to OOP spending. We propose to leverage the unique infrastructure of the CAFÉ randomized trial (R01CA237322) via the proposed supplemental study in response to NOT-CA-21-055. The proposed supplemental study is within the scope of parent grant, a randomized trial of a financial navigation intervention for people newly diagnosed with cancer. The supplemental study goal is to assess the patterns of health insurance plan coverage and OOP costs in the time surrounding a diagnosis of invasive cancer, as well as to understand the experiences of people with cancer who switched health insurance plans following an invasive cancer diagnosis. Specific Aim 1: Evaluate patterns of health insurance coverage and out-of-pocket spending prior to and following a cancer diagnosis, among adult members of KPNW and KPWA diagnosed with cancer. Specific Aim 2: Conduct a qualitative assessment of adult members with cancer who switched health insurance plan coverage using a descriptive phenomenological approach. The proposed mixed-methods supplement study will improve our understanding of insurance coverage change as a modifiable factor of cancer care costs, with high potential to inform future strategies to mitigate patient out of pocket spending related to cancer care.