The interaction of financial toxicity and social support on social functioning in post-chemotherapy breast cancer patients: a cross-sectional study

Purpose To explore the correlation between financial toxicity, social support, and social functioning in post-chemotherapy breast cancer patients, as well as any possible interaction of financial toxicity and social support on social functioning.Methods Post-chemotherapy breast cancer patients admitted to the thyroid and breast surgery departments of three first-class general hospitals in East China from December 2020 to January 2022 were recruited by convenience sampling for a cross-sectional survey. The survey instruments included the general information form, the comprehensive scores for financial toxicity based on the patient-reported outcome measures (COST-PROM), the social roles and activity participation subscale from the patient-reported outcomes measurement system-breast-chemotherapy (PROMS-B-C) (score range: 8-40), and the social support subscale from PROMS-B-C (score range: 16-80).Results The results showed that low social functioning (low score) in post-chemotherapy breast cancer patients was positively correlated with high financial toxicity (low score) as well as poor economic resources (low score) and poor psychosocial responses (low score) (P<0.01) and negatively correlated with low economic expenditures (low score) (P<0.01); high social functioning (high score) was positively correlated with high social support (high score) (P<0.01). The interaction analysis results showed an additive interaction between financial toxicity and social support in social functioning.Conclusion There was an additive interaction of financial toxicity and social support in the social functioning of post-chemotherapy breast cancer patients. Those patients with high financial toxicity and low social support are the most likely to benefit from relevant intervention measures compared to other breast cancer populations.