Janet Stanford of the Fred Hutchinson Cancer Research Center in Seattle and colleagues examined data on 630 prostate cancer patients, of whom 61 percent drank at least one cup of coffee a day.
Stanford said they wanted to see what relation coffee drinking might have with whether the prostate cancer came back or got worse.
"For the men that consumed at least one cup per day, risk of prostate cancer recurrence or progression was reduced by over 50 percent," Stanford said in a statement.
Coffee has chemicals that could affect cancer, but this needs more study, Stanford said.
The research was published in the journal Cancer Causes and Control was supported by the National Institutes of Health.