Fats and cancer

International comparisons of several human cancers indicate a wide variatio n in incidence and mortality among populations that genetic factors cannot explain thoroughly. These observations have suggested that environmental fa ctors and particularly dietary fats are important in the development of cer tain cancers like breast or prostate cancer. Experiments in animals showed that the amount and type of dietary fats influence tumor growth. These expe riments 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 f at intake and the incidence of cancers, larger studies with different popul ations and powerful analysis of individual fatty acids are needed before re commending nutritional changes in diet with the aim of reducing cancer risk in humans.