Patient assistance programs: a valuable, yet imperfect, way to ease the financial toxicity of cancer care.

High out-of-pocket (OOP) spending on cancer drugs is a known contributor to "financial toxicity" among cancer patients. Many predict that this problem will only worsen as patients continue to bear more responsibility for the cost of their medical care and as the use of oral chemotherapeutic agents increases. Although foundations and pharmaceutical companies offer patient assistance programs (PAPs) to improve drug affordability, the degree to which these programs are used is poorly understood. There are several barriers to the use of PAPs that not only affect access to patients who may benefit but also create limitations on the research and study of these programs.