Cancer and its treatments can cause a variety of symptoms. Some of these symptoms are related to the disease and others are seen as a consequence of the treatment. Since patients experience side effects to different degrees despite undergoing the same treatment, it is hypothesized that there is a genetic factor. The individual variation that exists between different patients regarding nausea triggered by chemotherapy, radiotherapy induced skin reactions as well as sleep disorders associated with cancer could partly be explained by genetic differences. We have in these studies confirmed these individual differences. Previous nursing research has mainly focused on the symptoms themselves. The focus in this thesis are the following three main symptoms; nausea and vomiting related to chemotherapy, acute skin inflammation following radiotherapy and sleep problems associated with cancer diagnosis and -treatment.

The aim of this thesis was to find biological markers that can identify the risk of and/or protective factors for nausea and/or vomiting (CINV) as well as understand its heterogeneity (Study 1 and 2). It also aimed to understand the individual factors behind acute radiation skin reactions (ARSR) (Study 3) and sleeping disturbances in patients treated for cancer (Study 4), permitting a more individualized care and optimized health-related quality of life (HRQoL).

In Study 1 and 2 the patients themselves had to document in a diary their experience of nausea and vomiting and well-being. Well-being was considered as synonymous with quality of life. We found a variability and heterogeneity of those symptoms (Study 1). Three genetic markers, FAS/CD95, RB1/LPAR6 and CCL2 that could explain the individual differences and assess the risk of chemotherapy-induced nausea were found in Study 2.

Acute radiation skin reactions (ARSR) along with itching and burning sensation associated with radiotherapy (RT) was assessed by the patients themselves (Study 3) with help of the VAS- and RTOG scales, scoring for visible redness. We found two possible genetic markers, XRCC2 and IFNG. Also, individual differences in symptoms behavior were found.

Sleep disturbances were common and were reported with obvious individual differences [1]. For data collection were used a sleep questionnaire, the Medical Outcomes Study Sleep Scale (MOS), open ended questions and EORTC QLQ- C30 questionnaire of quality of life. Sleep, which is important for all primary body functions, is often affected in connection with cancer diagnosis and -treatment.

Through collaboration between nursing staff and specialists in basic science, we have found that biological markers can help in creating individualized care. Knowledge of individual variations in the severity of chemo- or radiotherapy-induced side effects is important in order to better personalize the treatment and care, improve the treatment results and alleviate or prevent the side effects of oncological treatments. By linking symptoms to biological markers, it will hopefully be able to increase the patients’ total health-related quality of life, this being the main goal of this thesis.