Effects of Social Support and Rural–Urban Residence on Behavioral Financial Toxicity Among Patients With Cancer in China

Background: Cancer-related financial toxicity (FT) is a global challenge encompassing material burden, psychological distress, and cost-related behaviors such as delaying or forgoing treatment. Behavioral FT affects adherence but remains understudied. Objective: To examine independent, interactive, and combined associations of social support and residential setting with behavioral FT among patients with cancer. Methods: This secondary analysis included 1208 patients with cancer from 12 hospitals across 3 Chinese provinces. Hierarchical logistic regression examined independent associations and multiplicative interaction between social support and residential setting on behavioral FT, adjusting for 11 covariates. Additive interaction was assessed using relative excess risk due to interaction, attributable proportion, and synergy index. A 4-group composite variable was used to evaluate the combined association. Results: After adjustment for household income and other covariates, rural residence (odds ratio [OR] = 2.03, P < .001) and low social support (OR = 1.59, P = .005) were independently associated with greater behavioral FT, with no significant multiplicative or additive interaction. However, compared with urban high-support patients, the odds of behavioral FT increased progressively across the urban low-support (OR = 1.90, P = .036), rural high-support (OR = 2.19, P < .001), and rural low-support (OR = 3.26, P < .001) groups. Conclusions: Rural residence and low social support were independently associated with greater behavioral FT, with the highest vulnerability among patients experiencing both. Implications for Oncology Nursing Practice: Oncology nurses should routinely assess patients’ financial concerns and social support, particularly among rural patients, and facilitate referral to financial navigation and supportive services.