A nutrition intervention in men with prostate cancer : Exploring effects on bowel symptoms from radiotherapy, patient experience, and nutrient intake

Abstract: Objective The main objective of this thesis was to explore the effects of a nutrition intervention on acute and late bowel symptoms in men with localised prostate cancer treated with pelvic radiotherapy (study I), participants’ experiences from receiving the nutrition intervention (study II), and associations with nutrient intakes (study III).Methods A total of 180 men with localised prostate cancer referred to curative radiotherapy targeting the prostate gland and pelvic lymph nodes were recruited to the trial. The participants were randomised to standard care plus a nutrition intervention aiming to modify fibre and lactose intakes (NIG; n=92) or standard care alone (SCG; n=88). Data on bowel symptoms and dietary intake were collected pre-treatment and at seven time points during a 26-month study period. Analyses of the effects of the nutrition intervention on bowel symptoms were conducted for the acute phase (up to 2 months post radiotherapy), and the late phase (7 to 24 months post radiotherapy). Semi-structured interviews were conducted with 15 participants from the NIG to explore experiences of the nutrition intervention.Results The nutrition intervention was associated with statistically significantly, but not clinically significantly, less bother from blood in stools and flatulence during the acute phase. The nutrition intervention was also associated with more bloated abdomen during the late phase (Study I). Social support, contributing to the greater good, prior knowledge, dietary information, and a small need for change facilitated adherence. While feeling limited, wanting to decide for themselves, the timing of the intervention, unmet expectations, and loss of motivation were described as barriers for adherence (Study II). A greater reduction of lactose was associated with decreased intake of calcium at the end of the radiotherapy period. A more modified fibre intake during the radiotherapy period was associated with increased vitamin C, but decreased selenium intake (Study III).Conclusions The effects from the nutrition intervention were small and inconclusive and do not support routine dietary advice aiming to modify fibre and lactose intakes as a mean to substantially reduce adverse effects from pelvic radiotherapy. Tailored nutritional interventions based on individual preferences, prior knowledge, and context, could enhance adherence. There were few associations between modified fibre and lactose intakes and nutrient intakes, thus, no recommendations can be made on whether such dietary advice should continue to be provided to men with prostate cancer undergoing pelvic radiotherapy.