Sisira brought the subject up, in the context of red meat. He quotes Dr. Myers"
"He says in more than 100 papers in scientific literature that he has read, phytanic acid present in these foods can promote the growth and spread of prostate cancer."
& "Dr. Patrick Walsh in his book "Guide to Surviving Prostate Cancer" says the phytanic acid present in the fat of read meat and dairy products, when metabolized in the body makes a toxic by-product, hydrogen peroxide which can cause mutations in DNA leading to cancer or cancer progression."
There are actually only 15 hits on PubMed. But first, what is it?
"Phytanic acid ... is a ... fatty acid that humans can obtain through the consumption of dairy products, ruminant animal fats, and certain fish. Western diets are estimated to provide 50–100 mg of phytanic acid per day." 
"Unlike most fatty acids, phytanic acid cannot be metabolized by β-oxidation. Instead, it undergoes α-oxidation in the peroxisome, where it is converted into pristanic acid by the removal of one carbon. Pristanic acid can undergo several rounds of β-oxidation in the peroxisome to form medium chain fatty acids that can be converted to carbon dioxide and water in mitochondria."
"In ruminant animals, the gut fermentation of ingested plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats."
So the problem is chlorophyl - not fat, as such. So grain-fed beef is safer than grass-fed? Factory chickens are safer than free-roaming pasture-fed birds? Say it ain't so!
Here is a 2010 EPIC paper :
"Within the European Prospective Investigation into Cancer and Nutrition cohort, 566 incident prostate cancer cases from Germany, Greece, Italy, the Netherlands, Spain, and the United Kingdom were individually matched to 566 controls by study center, age at recruitment, and time of day and duration of fasting at blood collection."
"In controls, plasma phytanic acid concentration was strongly correlated with dairy fat intake .., varied significantly by country .., and decreased with age .. and duration of fasting at blood collection ... There was no significant association of phytanic acid with prostate cancer risk overall ... or by stage or grade of disease. However, in men who had fasted (>3 h) at blood collection, the odds ratio for prostate cancer was 1.27"
"Plasma phytanic acid concentration is significantly associated with intake of dairy fat but not with overall risk of prostate cancer in this European population."
Note that men with PCa who do research, will tend to avoid dairy.
Here is a 2014 ATBC study :
Included "blood samples from 300 prostate cancer cases and 300 matched controls, all of whom were participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study"
"In summary, we observed no overall association between serum phytanic and pristanic acid levels and prostate cancer risk."
Finally, a 2015 study :
"Men undergoing radical prostatectomy for the treatment of localized disease provided a food frequency questionnaire (n = 68), fasting blood (n = 35), benign fresh frozen prostate tissue (n = 26), and formalin-fixed paraffin-embedded (FFPE) sections (n = 67)."
"High-fat dairy intake was the strongest predictor of circulating phytanic acid concentrations"
"Our data underscore the complexity of the relationship between AMACR and its substrates and do not support the unifying hypothesis that excess levels of dietary phytanic acid are responsible for both the overexpression of AMACR in prostate cancer and the potential association between PCa risk and intake of dairy foods and red meat."
No cherry picking. Those were the only hits for <"phytanic acid" prostate men>.
Chlorophyl is off the hook.