Breast cancer-related lymphedema is an adverse effect of breast cancer surgery affecting nearly 30% of US breast cancer survivors (BCS). Our previous analysis showed that, even 12 years after cancer treatment, out-of-pocket healthcare costs for BCS with lymphedema remained higher than for BCS without lymphedema; however, only half of the cost difference was lymphedema-related. This follow-up analysis examines what, above and beyond lymphedema, contributes to cost differences.This mixed methods study included 129 BCS who completed 12 monthly cost diaries in 2015. Using Cohen's d and multivariable analysis, we compared self-reported costs across 13 cost categories by lymphedema status. We elicited quotes about specific cost categories from in-person interviews with 40 survey participants.Compared with BCS without lymphedema, BCS with lymphedema faced 122% higher mean overall monthly direct costs ($355 vs $160); had significantly higher co-pay, medication, and other out-of-pocket costs, lower lotion costs; and reported inadequate insurance coverage and higher costs that persisted over time. Lotion and medication expenditure differences were driven by BCS' socioeconomic differences in ability to pay.Elevated patient costs for BCS with lymphedema are for more than lymphedema itself, suggesting that financial coverage for lymphedema treatment alone may not eliminate cost disparities.The economic challenges examined in this paper have long been a concern of BCS and advocates, with only recent attention by policy makers, researchers, and providers. BCS identified potential policy and programmatic solutions, including expanding insurance coverage and financial assistance for BCS across socioeconomic levels.