That Cup of Joe Affects Your Prostate Cancer Risk

Abstract & commentary

By Rahul Gupta, MD, MPH, FACP, Clinical Assistant Professor, West Virginia University School of Medicine, Charleston, WV. Dr. Gupta reports no financial relationship relevant to this field of study.

Synopsis: Regular coffee consumption is associated with a prominent decrease in fatal or metastatic prostate cancer.

Source: Wilson KM, et al. Coffee consumption and prostate cancer risk and progression in the health professionals follow-up study. J Natl Cancer Inst 2011 May 17; Epub ahead of print.

Coffee has a long history of being blamed for many ills, sometimes justly. However, emerging research indicates that it may not be so bad after all. For instance, recent studies have demonstrated that coffee may have benefits, such as protecting against Parkinson's disease, type 2 diabetes mellitus, and liver cancer.1 In another prospective study of American men, coffee consumption was shown to prevent symptomatic gallstone disease.2 In addition to caffeine and some of the phytochemicals, coffee also has a high content of antioxidants. This has prompted researchers to investigate the relationship of malignancies with coffee consumption. In a study looking at two large cohorts of men and women, regular consumption of decaffeinated coffee was associated with a 52% reduction in incidence of rectal cancer compared to those who never consumed decaffeinated coffee whereas consumption of caffeinated coffee or tea with caffeine or caffeine intake was not associated with the incidence of colon or rectal cancer in either cohort.3 Similarly, in the present study, researchers attempted to investigate the relationship between coffee intake and risk of overall prostate cancer, including that of aggressive disease.

Using data from the Health Professionals Follow-up Study, Wilson et al conducted a prospective cohort study of 47,911 men followed for more than 20 years. Beginning in 1986, the study participants were followed through biennial questionnaires to update information on lifestyle and health outcomes, and usual diet (including intake of regular and decaffeinated coffee), and were assessed every 4 years. These men, who were 40-75 years old at the start of the study, completed a questionnaire about their health and lifestyle when they enrolled. They then answered regular follow-up questionnaires to update this information. The researchers also identified diagnoses of prostate cancer initially by self-reports from the men themselves or their relatives and then confirmed these by checking medical records and pathology reports. Deaths were ascertained through reports from family members and the National Death Index and the underlying cause of death was decided based on information such as medical records, registry information, and death certificates. Total prostate cancer incidence, excluding stage T1a cancers (which are discovered incidentally during treatment for benign prostatic hypertrophy), was studied. Data for men with advanced, lethal, or non-advanced cancers were examined separately to distinguish those patients in whom the cancer was likely to progress clinically.

The study participants overall consumed an average of 1.9 cups of coffee per day. During the 20 years of follow-up (from 1986 to 2006), the researchers found that 5035 of the 47,911 men were confirmed to have developed prostate cancer. Of these, 642 patients had lethal type prostate cancers (defined as fatal or metastatic), 896 were advanced, and 3,221 were non-advanced.

Researchers found that men drinking six or more cups per day had an 18% lower risk of overall prostate cancer compared with non-coffee drinkers (relative risk [RR], 0.82; 95% confidence interval [CI], 0.68-0.98). However, when only lethal forms of the prostate cancer were considered in this group, the risk was decreased by approximately 60% vs non-coffee drinkers (RR, 0.40; 95% CI, 0.22-0.75).

Additionally, both caffeinated and decaffeinated coffee appeared to decrease the risk for lethal prostate cancer. For each one cup per day increment, the risk declined by 6% for regular coffee (RR, 0.94; 95% CI, 0.88-1.01) and by 9% for decaffeinated coffee (RR, 0.91; 95% CI, 0.83-1.00; P = 0.05). Men drinking at least six cups a day had an age-adjusted incidence of only 425 prostate cancers per 100,000 person-years as opposed to 529 in those not consuming coffee. Likewise, the incidence of lethal prostate cancers was 34 vs 79 per 100,000 person-years in those drinking at least six cups vs nondrinkers, respectively. However, no association was found between coffee consumption and low-grade prostate cancers.

Commentary

Coffee contains biological compounds that improve glucose metabolism, have anti-inflammatory and antioxidant effects, and affect sex hormone levels, all of which may have played a role in prostate cancer progression. In fact, coffee is a major dietary source of antioxidants for Americans. This study provides a strong association between coffee consumption and lower risk of lethal and advanced cancers and the authors state that this appears to be related to non-caffeine components of coffee. We currently have not identified modifiable risk factors for advanced prostate cancer, which is the second-leading cause of cancer death among American men after lung cancer. However, the analyzed data from this well done large study (as well as some smaller ones in the past) are clearly insufficient for us to recommend that men start drinking gallons of coffee in an attempt to lower their prostate cancer risk.4 We would need to see these results replicated in other large studies before we can be sure whether coffee consumption affects the risk of prostate cancer. Additionally, heavy caffeine use (four to seven cups of coffee a day) can cause other problems such as tachycardia, restlessness, anxiety, irritability and sleeplessness, gastroesophageal reflux, and risk of heart disease in susceptible people. Also, we must keep in mind that for those drinking more than plain coffee, supplements such as cream and sugar contribute fat and calories to the diet. Therefore, at this time I would stick to the old dictum, "Everything in moderation."

References

1. Higdon JV, Frei B. Coffee and health: A review of recent human research. Crit Rev Food Sci Nutr 2006;46:101-123.

2. Leitzmann MF, et al. A prospective study of coffee consumption and the risk of symptomatic gallstone disease in men. JAMA 1999;281:2106-2112.

3. Michels KB, et al. Coffee, tea, and caffeine consumption and incidence of colon and rectal cancer. J Natl Cancer Inst 2005;97:282-292.

4. Park CH, et al. Coffee consumption and risk of prostate cancer: A meta-analysis of epidemiological studies. BJU Int 2010;106:762-769.