Lifestyle and Anthropometric Risk Factors for Prostate Cancer in a Cohort of Iowa Men

Abstract

PURPOSE: Several lines of evidence suggest that prostate cancer has a hormonal etiology. We evaluated factors known to modulate the endocrine system, including alcohol and tobacco use, physical activity, and obesity as risk factors for prostate cancer.

METHODS: Cancer-free controls $\text{n}\text{= 1572}$ who participated in a population-based case-control study from 1986–1989 (81% response rate) were followed through 1995 for cancer incidence by linkage to the Iowa Cancer Registry; 101 incident prostate cancers were identified.

RESULTS: Compared with non-users of alcohol, men who consumed <22 grams alcohol per week (relative risk [RR] = 1.1; 95% Confidence Interval [CI] 0.6–2.1), 22–96 grams alcohol per week (RR = 2.6; 95% CI 1.4–4.6) and >96 grams alcohol per week (RR = 3.1; 95% CI 1.5–6.3) were at increased risk of prostate cancer after adjustment for age, family history of prostate cancer, body mass index, total energy, and intake of carbohydrate, linoleic acid, lycopene, retinol, and red meat (p for trend < 0.0001). The respective RRs were similar when assessing type of alcohol consumed (beer, wine or liquor) or when well-differentiated, localized tumors were excluded. Body mass index was only weakly and positively associated with prostate cancer after adjustment for age $\text{p for trend}\text{= 0.3}$, but this association strengthened after multivariate adjustment $\text{p}\text{for trend}\text{= 0.08}$ and exclusion of well-differentiated, localized tumors $\text{p}\text{for trend}\text{= 0.03}$. For the latter tumors, men with a $\text{BMI of}\text{24.1–26.6}\text{kg}\text{/}\text{m}{}^2\text{RR}\text{= 1.5; 95\%}\text{CI}\text{0.7 – 3.0}$ and $\text{>26.6}\text{kg}\text{/}\text{m}{}^2\text{RR}\text{= 2.1; 95\%}\text{CI}\text{1.1–4.3}$ were at elevated risk compared to men with a BMI <24.1 kg/m². Tobacco use (cigarettes, cigar/pipe, chewing tobacco and snuff use), height, weight, and both leisure and occupational physical activity were not associated with risk of prostate cancer in this cohort.

CONCLUSIONS: These data suggest that in white men obesity is a risk factor for more clinically significant prostate cancer and confirm limited previous reports showing that alcohol consumption is positively associated with prostate cancer and that this risk is not limited to any specific type of alcohol.

Introduction

The American Cancer Society has estimated that over 184,000 men will be diagnosed with prostate cancer in the United States during 1998 (1). In addition, prostate cancer has risen to be the second leading cause of cancer-related death in the United States (2). Identifying risk factors for prostate cancer has been the subject of many epidemiological studies focusing on environmental and genetic factors, but there are currently few well established risk factors beyond age, race and family history (3).

There continues to be a strong interest in evaluating the role of steroid hormones in the etiology of prostate cancer, because many of these hormones, particularly testosterone, are integral to the normal growth and maintenance of the prostate gland 4, 5. We therefore evaluated the role of lifestyle (alcohol, smoking, and physical activity) and anthropometric (weight, height, and body mass) factors known to correlate with or modulate endogenous steroid hormones as prostate cancer risk factors in a population-based cohort of Iowa men.