Three-month-old C3H female mice were given
injections of 5-mg pieces of mammary
adenocarcinoma and were then fed diets that either were fat free or contained saturated fat (15% hydrogenated
cottonseed oil) or
linoleate (1-15%
corn oil). After 6 weeks, the
tumors in mice fed the
linoleate diet weighed 3-4 times more than those in mice fed the fat-free or saturated-fat diets. Despite a
linoleate-free diet,
tumors contained appreciable amounts of
linoleate and arachidonate (approximately 2 and 9% of the total
fatty acids, respectively). When the level of dietary
corn oil was increased from 1 to 15%, the
linoleate content of the
tumors increased from 4 to 18% of the total
fatty acids. However, in these instances, the
tumor arachidonate levels increased to maximum values even when the 1%
corn oil diet was used. These observations showed that mammary
tumor growth was depressed by a fat-free or saturated-fat diet and enhanced by dietary
linoleate. Furthermore, they suggested that the growth rate was related to the arachidonate content rather than the
linoleate content of the
tumors.