Dietary fats linked with prostate cancer aggressiveness

Higher concentrations of prostatic polyunsaturated fatty acids (PUFA) correlate with a lower risk of invasive disease among men with early-stage prostate carcinoma, US investigators report in the December 15th issue of Cancer.

"What this research suggests is that there is a very plausible and probable link between the types of fat consumed after the cancer has already developed and the level of aggressiveness or the extent of disease at the time the cancer is diagnosed and treated," lead author Dr. Vincent L. Freeman, of the University of Illinois at Chicago, told Reuters Health.Studies of the effects of different types of dietary fat intake on prostate cancer risk and prognosis have had mixed results, Dr. Freeman and colleagues note. They point out that many in the field believe biological measures of dietary exposure will be more helpful in clarifying the relationship than studies using dietary recall.To investigate the relationship between PUFA and invasiveness of early stage prostate carcinoma, Dr. Freeman's group tested 196 prostate tissue samples collected during radical prostatectomy for localized disease, using several measures of PUFA exposure. Fifty-two of the men had extracapsular extension, including 19 with seminal vesicle involvement.The researchers found significantly lower levels of PUFA in the men with seminal vesicle involvement. Omega-3 fatty acid percentage and arachidonic acid percentage also were inversely related to the risk of seminal vesicle involvement, as was the ratio of omega 3 to omega 6.There are a number of different mechanisms through which "good" fats like omega 3 fatty acids could help prevent cancer growth, Dr. Freeman noted. For example, while omega 6 acids such as linoleic acid can work through immune system pathways to fuel cancer spread and inhibit apoptosis, omega 3s can block these pathways from using "bad" fats as fuel. PUFAs can also influence communication both within and between cells in other ways, while oxidation of PUFAs can lead to DNA damage.According to Dr. Freeman, the percentage of PUFAs in prostate tissue is likely an accurate marker for long-term fat consumption. "We are reasonably confident that that does reflect some longer term pattern of intake, a pattern of intake long enough to have influence over disease aggressiveness," he said.The researchers conclude: "Because the differences in prostatic concentrations of PUFA were not large, levels associated with a reduced risk of locally advanced prostate carcinoma would appear to be achievable through dietary modification. However, the results of recent attempts to manipulate tissue nutrient levels through dietary modification have been mixed, suggesting that much technical work remains before this can become a feasible and effective preventive strategy."(Source: Cancer 2004;101:2744-2754: Reuters Health: Anne Harding: Oncolink: January 2005.)