Biological mediators of effect of diet and stress reduction on prostate cancer

Abstract

Background. A 6-month pilot intervention trial was conducted to determine whether adoption of a plant-based diet, reinforced by stress reduction, could reduce the rate of prostate-specific antigen (PSA) increase, a marker of disease progression, in asymptomatic, hormonally untreated patients experiencing consistently increasing PSA levels after surgery or radiation. Methods. A pre-post design was used to examine (1) the effect of intervention on potential mediators of disease progression, including body composition and weight-related biomarkers (sex steroid hormones and cytokines), and (2) whether changes in these variables were associated with change in rate of PSA increase. The baseline rate of PSA increase (from the time of posttreatment recurrence to the start of intervention) was ascertained from medical records. Body composition and biomarkers were assessed at baseline (prior to intervention), during the intervention (3 months), and at the end of the intervention (6 months). Changes in body composition and biomarkers were determined and compared with rates of PSA increase over the corresponding time intervals. Results. There was a significant reduction in waist-to-hip ratio (P =.03) and increase in circulating sex hormone binding globulin (P =.04). The rate of PSA increase decreased from the preintervention period (PSA slope = 0.059) to the period from 0 to 3 months (PSA slope = 0.002, P