Dietary fat and prostate cancer progression and survival

Background: The association between dietary factors and the occurrence of p rostate cancer has been studied extensively, but there is, as yet, no publi shed study on the relationship between diet and disease progression among p rostate cancer patients. We studied the association between dietary fat int ake and prostate cancer survival. Methods: We prospectively followed 384 me n diagnosed with prostate cancer between 1990 and 1992 in the Quebec City a rea who participated in a case-control study of diet in relation to prostat e cancer occurrence. Trained nutritionists interviewed the men on their usu al diet using a diet history questionnaire. Deaths in the follow-up were do cumented through record linkage with the provincial mortality file and revi ew of hospital records. The cause of death was taken as written on the deat h certificate. Cox proportional hazards models were used to estimate the re lative risk of dying from prostate cancer associated with terciles of fat i ntake, expressed as percent of dietary energy, while controlling for progno stic factors and total energy. Results: The median duration of follow-up wa s 5.2 years. During the follow-up period, 32 patients died of prostate canc er and 39 died of other causes. The 5-year disease-specific survival was 91 %. After controlling for grade, clinical stage, initial treatment, age and total energy intake, we found that saturated fat consumption was significan tly associated with disease-specific survival (p = 0.008). Compared to men in the lower tercile of saturated fat, those in the upper tercile had three times the risk of dying from prostate cancer (hazards ratio 3.13, 95% conf idence interval 1.28-7.67). Conclusion: Our findings suggest that, if satur ated fat is causally related to disease-specific survival, a moderate reduc tion of its intake below 10% of energy should reduce the risk of dying from prostate cancer. This dietary goal is already recommended for health promo tion and primary prevention of heart disease and cancer.