ROCHESTER, Minn. -- Regular use of aspirin, ibuprofen and other common painkillers appear to protect against prostate cancer among older men, Reuters quoted Mayo Clinic researchers as saying on Tuesday. Men over age 60 who took a daily dose of one of the drugs known collectively as non-steroidal anti-inflammatory drugs (NSAIDs) were half as likely to develop the disease, which is the second-leading cancer killer among U.S. men with more than 30,000 deaths expected this year. The 5 1/2-year study of 1,362 white men in Minnesota found 4 percent of those who took the drugs developed prostate cancer, versus 9 percent of those who did not. The older the patient, the more pronounced the protective effect of the drugs, the study said. But Mayo Clinic researcher Rosebud Roberts, writing in the journal **** Mayo Clinic Proceedings ****, cautioned that the results were inconclusive and needed confirmation. "We also need to determine the duration and dosage use that provides protection against prostate cancer, and to better understand the biologic mechanisms underlying the association between NSAIDs and prostate cancer," Roberts said. In addition, regular use of such drugs can be harmful, causing stomach problems and liver damage in some people. Roberts said previous studies have shown NSAIDs offer protection against breast cancers in women and against colon cancer. The study, part of a larger survey, was also focused solely on white male subjects. "African American men have the highest risk of prostate cancer. We need to complete additional research to determine if these findings are applicable to them," Roberts said.