Consuming four or more cups of coffee a day could reduce the risk of prostate cancer recurrence and disease progression, according to a study published in the journal Cancer Causes and Control.

Researchers from the Fred Hutchinson Cancer Research Center in Seattle analyzed 1,001 prostate cancer survivors from a population-based study, aged between 35 and 74 years of age. All survivors had been diagnosed with the disease between 2002 and 2005.

The participants were asked to complete a food frequency questionnaire two years before their prostate cancer diagnosis, and were required to give information regarding their diet and beverage consumption.

The participants were also interviewed about their:

  • Demographic and lifestyle information
  • Family history of cancer
  • Medication use
  • Prostate cancer screening history.

The researchers ran a follow-up analysis five years after the participants' first diagnosis to find out whether the prostate cancer had recurred and/or progressed. Of the original 1,001 participants, 630 then answered questions about their coffee intake and were included in the final results.

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Less recurrence or progression of prostate cancer

The analysis showed that of these participants, 61% consumed at least one cup of coffee a day, while 12% drank four or more cups of coffee a day.

The men who drank four or more cups of coffee a day had 59% less risk of prostate cancer recurrence and/or progression than those whose coffee consumption was just one cup a week or less.

Additionally, the researchers analyzed the link between coffee consumption and prostate cancer-specific death in 894 patients included in the original food frequency questionnaire.

Results showed that 125 men had died after the median follow-up period of 8.5 years. Of these, 38 had died specifically from prostate cancer, but daily coffee consumption was not associated with these deaths.

There was no link found between coffee consumption and reduced mortality from prostate cancer, the researchers add, although they note this study did not include enough men who died from the disease to address that as a separate issue.

Milan Geybels, a previous student at the Fred Hutchinson Cancer Research Center and lead author of the study, says the results of this study differ from those of other studies looking at the same link, as the researchers used a "composite definition" of prostate cancer recurrence/progression. He adds:

"We used detailed information on follow-up prostate-specific antigen levels, use of secondary treatment for prostate cancer and data from scans and biopsies to assess occurrence of metastases and cause-specific mortality during follow up.

Using these detailed data, we could determine whether a patient had evidence of prostate cancer recurrence or progression."

The study authors add that further research is needed to determine exactly how coffee may have effects against prostate cancer. But they say biological activities linked to consumption of phytochemical compounds found in coffee can have "anti-inflammatory and antioxidant effects."

The researchers say that these naturally occurring compounds include:

  • Caffeine, "which can inhibit cell growth and encourage apoptosis"
  • Diterpenes cafestol and kahweol, "which can inhibit cancer growth"
  • Chlorogenic acid, "which can inhibit DNA methylation".

'Don't start drinking lots of coffee - it may be harmful'

The study authors warn that although these results indicate a positive link between higher coffee consumption and reducing the recurrence and progression of prostate cancer, the preventive effect needs to be demonstrated within clinical trials before coffee can be recommended for secondary prevention.

Milan Geybels says:

"Although coffee is a commonly consumed beverage, we have to point out that increasing one's coffee intake may be harmful for some men. For instance, men with hypertension may be vulnerable to the adverse effects of caffeine in coffee.

Or, specific components in coffee may raise serum cholesterol levels, posing a possible threat to coronary health. Patients who have questions or concerns about their coffee intake should discuss them with their general practitioner.

This research is the latest in a variety of studies that claim health benefits, and also risks, of coffee consumption.

US researchers found that drinking four or more cups of coffee a day was linked to risk of early death.

However, a July 2013 study from the Harvard School of Public Health found that suicide risk in adults was lower among those who drank 2 to 4 cups of coffee a day.