The study, published in Cancer Causes & Control, investigated whether the bioactive compounds in coffee and tea had preventative effects on prostate cancer recurrence or reduced progression of the disease - finding that consumption of more than four cups of coffee may provide anti-inflammatory and antioxidant effects that could result in a lower risk of recurrence or progression.
Led by Dr Janet Stanford from the Fred Hutchinson Cancer Research Center, USA, the team behind the study found men who drank four or more cups of coffee per day experienced a 59% reduced risk of prostate cancer recurrence and/or progression as compared to those who drank only one or fewer cups per week.
They did not, however, find an association between coffee drinking and reduced mortality from prostate cancer. However Stanford and her team noted that the study included too few men who died of prostate cancer to address the issue separately.
Indeed, coffee drinking may even be problematic for some men, said the team: "Although coffee is a commonly consumed beverage, we have to point out that increasing one's coffee intake may be harmful for some men," explained Milan Geybels of Maastricht University in the Netherlands, first author of the study.
"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," he said.
The population-based study involved 1,001 prostate cancer survivors, aged 35-74 years old at the time of diagnosis between 2002-2005. Participants answered questions regarding their diet and beverage consumption two years prior to prostate cancer diagnosis using a validated food frequency questionnaire, and were interviewed about demographic and lifestyle information, family history of cancer, medication use and prostate cancer screening history.
The researchers followed up with patients more than five years after diagnosis to ascertain whether the prostate cancer had recurred and/or progressed. Of the original 1,001 patients in the cohort, 630 answered questions regarding coffee intake, fit the follow-up criteria and were included in the final analysis.
Of those, 61% of the men consumed at least one cup of coffee per day and 12% consumed the highest amount: four or more cups per day.
"Our study differs from previous ones because we used a composite definition of prostate cancer recurrence/progression," explained Geybels. "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 team said that their results are consistent with findings from the Harvard's Health Professionals Follow-up Study - which found that men who drank six or more cups of coffee per day had a 60% decreased risk of metastatic/lethal prostate cancer as compared to coffee abstainers.