Objectives: Relationships between dietary factors and the incidence of prostate cancer have emerged from epidemiologic and laboratory studies, but there are no published data on the relationship between diet and disease progression among prostate cancer patients. We studied the association between dietary fat intake and prostate cancer survival.
Methods: We prospectively followed 384 men diagnosed with prostate cancer between 1990 and 1992 in the Quebec City area. On average 3 months following diagnosis, trained nutritionists interviewed the men on their usual diet using a diet history questionnaire. Deaths during follow-up were documented through record linkage with the provincial mortality file and review of hospital records. Cox proportional hazard models were used to estimate the relative risk of dying from prostate cancer associated with terciles of fat intake, expressed as percent of dietary energy, while controlling for prognostic factors and total energy.
Results: The median duration of follow-up was 5.2 years. During the follow-up period 32 patients died of prostate cancer and 39 died of other causes. After controlling for grade, clinical stage, initial treatment, age and total energy intake, we found that saturated fat consumption was significantly associated with disease-specific survival (two-sided p-value = 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 (relative risk = 3.1, 95% confidence interval: 1.3-7.7).
Conclusions: Our findings suggest that saturated fat is related to disease-specific survival and that, if this relation is causal, a moderate reduction of its intake might reduce the risk of dying from prostate cancer.