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Sun Exposure May Confound Physical Activity–Prostate Cancer Association—Reply

Sun Exposure May Confound Physical Activity–Prostate Cancer Association—Reply In reply Aydin suggests that the inverse association between higher levels of vigorous physical activity and risk of advanced prostate cancer in older men may be related to solar UV exposure.1 Exposure to sun while exercising outdoors is a source of vitamin D production, and in a sample of men in our cohort, those who reported higher levels of physical activity indeed had higher circulating 25-hydroxyvitamin D concentrations. However, both nonvigorous and vigorous activities were associated with higher 25-hydroxyvitamin D concentrations, but for advanced prostate cancer, only vigorous activity was associated with lower risk. Thus, sun exposure is unlikely to be the major factor, though the general point that solar UV-B exposure may contribute to some of health benefits observed with a higher physical activity level is noteworthy. Ross suggests that exercise may lower risk through benefits on glycemic control in men with the metabolic syndrome. Insulin has growth-promoting properties and increases free insulinlike growth factor 1 levels.2 A case-control study in China (a population with low obesity rates) found a 2.6-fold higher risk of prostate cancer comparing the top to bottom tertiles of fasting plasma insulin.3 Also, higher fasting plasma glucose level was positively and higher insulin sensitivity was inversely related to prostate cancer risk.4 No association between insulin and prostate cancer was observed in a prospective study in Sweden.5 Hyperglycemia was associated with a nonstatistically significant increase risk of prostate cancer in another prospective study.6 Increased serum insulin has been associated with increased risk of prostate cancer recurrence.7 Two recent studies found that the metabolic syndrome was associated with increased risk of prostate cancer.8,9 Thus, some evidence suggests that a high insulin or glucose level may increase the risk of prostate cancer incidence or progression. However, it is somewhat paradoxical that men with type 2 diabetes mellitus have a reduced risk of prostate cancer,10 and the relationship between obesity and prostate cancer is unclear. Diabetes and obesity may influence other hormonal systems, such as androgens, that may also affect prostate cancer risk. Examination of vigorous activity in relation to various hormonal axes in older men may help us to better understand the relationship between physical activity and prostate cancer. Correspondence: Dr Giovannucci, Departments of Nutrition and Epidemiology, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115 (edward.giovannucci@channing.harvard.edu). References 1. Giovannucci ELLiu YLeitzmann MFStampfer MJWillett WC A prospective study of physical activity and incident and fatal prostate cancer. Arch Intern Med 2005;1651005- 1010PubMedGoogle ScholarCrossref 2. Giovannucci E Nutrition, insulin, insulin-like growth factors and cancer. Horm Metab Res 2003;35694- 704PubMedGoogle ScholarCrossref 3. Hsing AWChua S JrGao YT et al. Prostate cancer risk and serum levels of insulin and leptin: a population-based study. J Natl Cancer Inst 2001;93783- 789PubMedGoogle ScholarCrossref 4. Hsing AWGao YTChua SDeng JStanczyk FZ Insulin resistance and prostate cancer risk. J Natl Cancer Inst 2003;9567- 71PubMedGoogle ScholarCrossref 5. Stattin PBylund ARinaldi S et al. Plasma insulin-like growth factor-I, insulin-like growth factor-binding proteins, and prostate cancer risk: a prospective study. J Natl Cancer Inst 2000;921910- 1917PubMedGoogle ScholarCrossref 6. Gapstur SMGann PHColangelo LA et al. Postload glucose concentration and 27-year prostate cancer mortality (United States). Cancer Causes Control 2001;12763- 772PubMedGoogle ScholarCrossref 7. Lehrer SDiamond EJStagger SStone NNStock RG Increased serum insulin associated with increased risk of prostate cancer recurrence. Prostate 2002;501- 3PubMedGoogle ScholarCrossref 8. Hammarsten JHogstedt B Clinical, haemodynamic, anthropometric, metabolic and insulin profile of men with high-stage and high-grade clinical prostate cancer. Blood Press 2004;1347- 55PubMedGoogle ScholarCrossref 9. Laukkanen JALaaksonen DENiskanen LPukkala EHakkarainen ASalonen JT Metabolic syndrome and the risk of prostate cancer in Finnish men: a population-based study. Cancer Epidemiol Biomarkers Prev 2004;131646- 1650PubMedGoogle Scholar 10. Giovannucci E Medical history and etiology of prostate cancer. Epidemiol Rev 2001;23159- 162PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Internal Medicine American Medical Association

Sun Exposure May Confound Physical Activity–Prostate Cancer Association—Reply

Archives of Internal Medicine , Volume 165 (21) – Nov 28, 2005

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Publisher
American Medical Association
Copyright
Copyright © 2005 American Medical Association. All Rights Reserved.
ISSN
0003-9926
eISSN
1538-3679
DOI
10.1001/archinte.165.21.2539
Publisher site
See Article on Publisher Site

Abstract

In reply Aydin suggests that the inverse association between higher levels of vigorous physical activity and risk of advanced prostate cancer in older men may be related to solar UV exposure.1 Exposure to sun while exercising outdoors is a source of vitamin D production, and in a sample of men in our cohort, those who reported higher levels of physical activity indeed had higher circulating 25-hydroxyvitamin D concentrations. However, both nonvigorous and vigorous activities were associated with higher 25-hydroxyvitamin D concentrations, but for advanced prostate cancer, only vigorous activity was associated with lower risk. Thus, sun exposure is unlikely to be the major factor, though the general point that solar UV-B exposure may contribute to some of health benefits observed with a higher physical activity level is noteworthy. Ross suggests that exercise may lower risk through benefits on glycemic control in men with the metabolic syndrome. Insulin has growth-promoting properties and increases free insulinlike growth factor 1 levels.2 A case-control study in China (a population with low obesity rates) found a 2.6-fold higher risk of prostate cancer comparing the top to bottom tertiles of fasting plasma insulin.3 Also, higher fasting plasma glucose level was positively and higher insulin sensitivity was inversely related to prostate cancer risk.4 No association between insulin and prostate cancer was observed in a prospective study in Sweden.5 Hyperglycemia was associated with a nonstatistically significant increase risk of prostate cancer in another prospective study.6 Increased serum insulin has been associated with increased risk of prostate cancer recurrence.7 Two recent studies found that the metabolic syndrome was associated with increased risk of prostate cancer.8,9 Thus, some evidence suggests that a high insulin or glucose level may increase the risk of prostate cancer incidence or progression. However, it is somewhat paradoxical that men with type 2 diabetes mellitus have a reduced risk of prostate cancer,10 and the relationship between obesity and prostate cancer is unclear. Diabetes and obesity may influence other hormonal systems, such as androgens, that may also affect prostate cancer risk. Examination of vigorous activity in relation to various hormonal axes in older men may help us to better understand the relationship between physical activity and prostate cancer. Correspondence: Dr Giovannucci, Departments of Nutrition and Epidemiology, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115 (edward.giovannucci@channing.harvard.edu). References 1. Giovannucci ELLiu YLeitzmann MFStampfer MJWillett WC A prospective study of physical activity and incident and fatal prostate cancer. Arch Intern Med 2005;1651005- 1010PubMedGoogle ScholarCrossref 2. Giovannucci E Nutrition, insulin, insulin-like growth factors and cancer. Horm Metab Res 2003;35694- 704PubMedGoogle ScholarCrossref 3. Hsing AWChua S JrGao YT et al. Prostate cancer risk and serum levels of insulin and leptin: a population-based study. J Natl Cancer Inst 2001;93783- 789PubMedGoogle ScholarCrossref 4. Hsing AWGao YTChua SDeng JStanczyk FZ Insulin resistance and prostate cancer risk. J Natl Cancer Inst 2003;9567- 71PubMedGoogle ScholarCrossref 5. Stattin PBylund ARinaldi S et al. Plasma insulin-like growth factor-I, insulin-like growth factor-binding proteins, and prostate cancer risk: a prospective study. J Natl Cancer Inst 2000;921910- 1917PubMedGoogle ScholarCrossref 6. Gapstur SMGann PHColangelo LA et al. Postload glucose concentration and 27-year prostate cancer mortality (United States). Cancer Causes Control 2001;12763- 772PubMedGoogle ScholarCrossref 7. Lehrer SDiamond EJStagger SStone NNStock RG Increased serum insulin associated with increased risk of prostate cancer recurrence. Prostate 2002;501- 3PubMedGoogle ScholarCrossref 8. Hammarsten JHogstedt B Clinical, haemodynamic, anthropometric, metabolic and insulin profile of men with high-stage and high-grade clinical prostate cancer. Blood Press 2004;1347- 55PubMedGoogle ScholarCrossref 9. Laukkanen JALaaksonen DENiskanen LPukkala EHakkarainen ASalonen JT Metabolic syndrome and the risk of prostate cancer in Finnish men: a population-based study. Cancer Epidemiol Biomarkers Prev 2004;131646- 1650PubMedGoogle Scholar 10. Giovannucci E Medical history and etiology of prostate cancer. Epidemiol Rev 2001;23159- 162PubMedGoogle ScholarCrossref

Journal

Archives of Internal MedicineAmerican Medical Association

Published: Nov 28, 2005

Keywords: physical activity,prostate cancer,sun exposure

References