Fats and cancer

International comparisons of several human cancers indicate a wide variation in incidence and mortality among populations that genetic factors cannot explain thoroughly. These observations have suggested that environmental factors and particularly dietary fats are important in the development of certain cancers like breast or prostate cancer. Experiments in animals showed that the amount and type of dietary fats influence tumor growth. These experiments suggest that n-3 fatty acids are protective whereas n-6 fatty acids increase the growth of tumors. Case-control studies support these results but most cohort studies do not corroborate an association between dietary fat intake and the incidence of cancers, larger studies with different populations and powerful analysis of individual fatty acids are needed before recommending nutritional changes in diet with the aim of reducing cancer risk in humans.