Biological mediators of effect of diet and stress reduction on prostate cancer.
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<.01) and increased slightly, although not significantly, from 0 to 3 months to the period from 3 to 6 months (0.029, P=.43).


CONCLUSIONS
Adoption of a plant-based diet and stress reduction may reduce central adiposity and improve the hormonal milieu in patients with recurrent PC. Changes in the rate of increase in PSA were in the same direction as changes in waist-to-hip ratio and opposite those of sex hormone binding globulin, raising the possibility that the effect of the intervention may have been mediated, in part, by these variables.
Saxe
Gordon A
GA
Department of Family and Preventive Medicine, University of California, San Diego, Moores UCSD Cancer Center, San Diego, La Jolla, California 92093-0901, USA. gsaxe@ucsd.edu
Major
Jacqueline M
JM
Westerberg
Lindsey
L
Khandrika
Srikrishna
S
Downs
Tracy M
TM
D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D016207:Cytokines / Q000378:metabolism; D014676:Diet, Vegetarian; D018450:Disease Progression; D005500:Follow-Up Studies; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000628:therapy*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013315:Stress, Psychological / Q000517:prevention & control*; D049629:Waist-Hip Ratio
D016207:Cytokines; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin; D017430:Prostate-Specific Antigen