Introduction. Breast cancer is a serious health, social and economic problem due to its prevalence. Social costs include all types of costs including irrational costs that relate to physical and mental suffering and pain. Aim. The main goal is to analyse the irrational costs of breast cancer treatment - to determine their severity, prevalence and methods of elimination. Material and methods. The study was conducted among 72 adult women treated for breast cancer. The questions concerned intensification and prevalence of perceived ailments and actions taken by women to minimize them. We used author’s questionnaire. The U Mann-Whitney test was used to evaluate the differences between the groups, and the compatibility of distributions of the variables was tested using the W Shapiro-Wilk test – the level of significance was set at p <0.05. Results. It was found that irrational costs are a common phenomenon in oncological treatment. The biggest concerns were associated with chemotherapy, and the most common declared symptoms were general weakness of the body as well as hair loss and alopecia. Older women felt also significantly worse after surgical treatment (p=0.021). Irrational costs were eliminated by such activities as the purchase of a wig or breast reconstruction. It was found that older women were less likely to buy a wig (p=0.0207) and reconstructive surgery (p=0.021). Conclusions. Irrational costs associated with breast cancer treatment, such as pain or anxiety, are a common phenomenon and can be a serious challenge in planning oncology treatment. Demographic factors have a partial impact on the actions taken by women to eliminate or reduce the perceived consequences of treatment.

Key words: irrational costs, breast cancer, well-being.