Dissertation/Thesis Abstract

Self-reported exercise and risk of osteoporosis in prostate cancer patients receiving androgen deprivation therapy
by Mennen-Winchell, Lori J., Dr.P.H., Loma Linda University, 2011, 177; 3721215
Abstract (Summary)

Prostate cancer is stimulated to grow in response to testosterone. Androgen deprivation therapy (ADT) leads to chemical castration and suppression of prostate cancer cell production. Testosterone levels less then 300ng/ml decreases bone mineral density and could result in osteoporosis. Studies have shown that during the first year of ADT, fracture risk, mainly in hips and spine increases about 50%. In men, 40% of hip fractures result in death. Exercise may reduce the risk of osteoporosis and thus contribute to the prevention of hip and other fractures. There is limited data regarding whether exercise is associated with a reduced risk of osteoporosis in men treated with ADT.

Purpose of this study was to evaluate the relationship between self-reported exercise and bone mineral density measured by dual-energy x-ray absorptiometry (DEXA) and 25 hydroxy vitamin D levels in prostate cancer patients receiving ADT.

A convenience sample of 96 men with prostate cancer treated with ADT for a minimum of nine months or longer and up to the time of inclusion in the study completed the Canadian Fitness Survey questionnaire to assess the amount and types of exercise performed. In addition, questions from a section of the NHANES survey about cigarette and alcohol use, history of non traumatic fracture, diseases causing fracture, and use of medication including calcium supplementation were asked. A serum vitamin D level and DEXA scan were completed within a specified time period based on length of time receiving ADT. Subjects were recruited from eight urology practices and one cancer center in Clark County, Nevada.

The relationships between total duration of exercise, intensity, frequency, bone density T-scores, and serum vitamin D were examined using correlation analysis, as was the relationship between specific types of exercise, measured the same way and bone density T-scores. Furthermore, regression analysis was used to examine for potential confounders. Confounders identified for this study include age, body mass index, cigarette smoking, alcohol use, history of non-traumatic fracture or disease causing fracture, and use of medication, including calcium supplementation. Regression analysis was conducted to determine if there was an independent association between exercise and bone mineral density and serum vitamin D. This study provides evidence associating exercise with reduced risk of osteoporosis in patients receiving ADT.

The second study looked at determinants of 25 OH vitamin D. We found that the only independent modifiable determinant was vitamin D supplementation of ≥800 IU/day. Avoiding osteoporosis by increasing exercise in this group of patients is a practical measure that preventive care specialists could institute.

Indexing (document details)
Advisor: Tonstad, Serena
Commitee: Alpert, Patricia, DosSantos, Hildemar, Grigoriev, Victor
School: Loma Linda University
Department: Health Promotion and Education
School Location: United States -- California
Source: DAI-B 77/01(E), Dissertation Abstracts International
Subjects: Public health, Oncology
Keywords: Androgen deprivation, Bone mineral density, Osteoporosis, Physical exercise, Prostate cancer, Vitamin D
Publication Number: 3721215
ISBN: 978-1-339-02629-9
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