...ask that person if he/she has read the following:

[Cancer Research 45, 1997-2001, May 1, 1985]

In an attempt to determine the requirement of essential fatty acid for
dimethylbenz(a)anthracene-induced mammary tumorigenesis, rats were fed
diets containing different levels of linoleate: 0.5, 1.1, 1.7, 2.2,
3.5, 4.4, 8.5, or 11.5%. Each diet contained 20% of fat by weight,
with varying amounts of coconut oil and corn oil added to achieve the
desired levels of linoleate. Mammary tumorigenesis was very sensitive
to linoleate intake and increased proportionately in the range of 0.5
to 4.4% of dietary linoleate. Regression analysis indicated that a
breakpoint occurred at 4.4%, beyond which there was a very poor linear
relationship, suggesting the possibility of a plateau. From the
intersection of the regression lines in both the upper and lower
ranges, the level of linoleate required to elicit the maximal
tumorigenic response was estimated to be around 4%. The differences in
tumor yield could not be correlated with changes in prostaglandin E
concentration in the mammary fat pads of normal animals maintained on
similar diets, suggesting that linoleate may act by some other
mechanism to stimulate mammary tumorigenesis.

http://cancerres.aacrjournals.org/cgi/content/abstract/45/5/1997