In oncology, the term “financial toxicity” means the financial hardship or financial burden for patients and families that arise from cancer treatment and ongoing expenses. Individuals from any socioeconomic group may experience this, and it can occur in both low- and high-income countries. There are 2 key contributors: (1) high medical payments by individuals/households and (2) reduced income while being treated or recovering from cancer. The former is likely to affect more individuals in high-income countries, whereas the latter is more problematic in poor households although, clearly, individuals will be worse when faced with both high out-of-pocket medical expenses (outgoings) and concurrent loss of earnings (incomings). In some studies, financial hardship is defined as spending greater than 30% of household income on healthcare and is termed “catastrophic spending.”1