This study assessed the extent to which individuals with surgically operable cancer in Southeast Asia experience financially catastrophic out-of-pocket costs, discontinuation of treatment, or death.The ACTION study is a prospective, 8-country, cohort study of adult patients recruited consecutively with an initial diagnosis of cancer from public and private hospitals. Participants were interviewed at baseline and 3 months. In this paper, we identified 4,584 participants in whom surgery was indicated in initial treatment plans and assessed the following competing outcomes: death, financial catastrophe (out-of-pocket costs of >30% of annual household income), treatment discontinuation, and hospitalization without financial catastrophe incurred. We then analyzed a range of predictors using a multinomial regression model.Of the participants, 72% were female and 44% had health insurance at baseline. At 3 months, 31% of participants incurred financial catastrophe, 8% had died, 23% had discontinued treatment, and 38% were hospitalized but avoided financial catastrophe. Health insurance status was found to be associated with lower odds of treatment discontinuation (odds ratio [OR], 0.60; 95% CI, 0.47-0.77) relative to hospitalization without financial catastrophe. Women had greater odds of financial catastrophe than men (OR, 1.35; 95% CI, 1.05-1.74), whereas lower socioeconomic status (range of indicators) was generally found to be associated with higher odds of death, treatment discontinuation, and financial catastrophe.Priority should be given to measures such as programs to extend social health insurance to offset the out-of-pocket costs associated with surgery for cancer faced in particular by women, the uninsured, and individuals of low socioeconomic status in Southeast Asia.