Breast cancer is the most frequently occurring cancer, assuming that it accounts for 29% of all new cancers in women (European Cancer Information System). The number of long-term survivors is increasing rapidly due to improving accuracy of the detecting methods, the early diagnosis and advances in cancer treatment. The International Consortium for Health Outcomes Measurement Initiative described upper limb (UL) function as the health outcome that matters most for breast cancer survivors (BCS). 50% of BCS at 6 months post-radiotherapy suffer from of decreased UL function, i.e. difficulties in performing activities of daily living with the upper limb. Patients experiencing UL dysfunctions and other problems are less likely to be physically active. Given that physical inactivity is associated with an increased risk of mortality after breast cancer, taking away the barriers to physical activity (e.g. UL dysfunctions) is very important. Identifying these factors contributing to chronic UL dysfunction is important in terms of identifying targets for prospective evaluation and specific treatment approaches at specific time points during breast cancer treatment. This study aims to find reliable and valid assessment methods for the prognostic factors and upper limb function itself in a small group of BCS and healthy volunteers.