Sauer LA, Dauchy RT, and Blask DE,Polyunsaturated fatty acids, melatonin, and cancer prevention. Biochem Pharmacol,2001;61(12):1455-1462

Many nutritional, hormonal, and environmental factors affect carcinogenesis and growth of established tumors in rodents. In some cases, these factors may either enhance or attenuate the neoplastic process.

Recent experiments performed in our laboratory using tissue-isolated rat hepatoma 7288CTC in vivo or during perfusion in situ have demonstrated new interactions among four of these factors. Two agents, dietary linoleic acid (C18:2n6) and "light at night," enhanced tumor growth, and two others, melatonin and n3 fatty acids, attenuated growth. Linoleic acid stimulated tumor growth because it is converted by hepatoma 7288CTC to the mitogen, 13-hydroxyoctadecadienoic acid (13-HODE).

Melatonin, the neurohormone synthesized and secreted at night by the pineal gland, and dietary n3 fatty acids are potent antitumor agents. Both inhibited tumor linoleic acid uptake and 13-HODE formation. Artificial light, specifically "light at night," increased tumor growth because it suppressed melatonin synthesis and enhanced 13-HODE formation.

Melatonin and n3 fatty acids acted via similar or identical G(i) protein-coupled signal transduction pathways, except that melatonin receptors and putative n3 fatty acid receptors were used. The results link the four factors in a common mechanism and provide new insights into the roles of dietary n6 and n3 polyunsaturated fatty acid intake, "light at night," and melatonin in cancer prevention in humans.

Hendrickse CW, Keighley MR, Neoptolemos JP. Dietary omega-3 fats reduce proliferation and tumor yields at colorectal anastomosis in rats. Gastroenterology 1995; 109(2):431-439.

BACKGROUND & AIMS: Colorectal anastomoses show increased mucosal crypt cell proliferation rates (CCPRs) and often form the site for tumor recurrence after resection of colorectal cancer. The aim of this study was to assess the effects of a 20% omega-3 fat diet on CCPRs and anastomotic tumor formation compared with an isocaloric 20% saturated fat diet in experimental colorectal cancer.

METHODS: One hundred sixty male Wistar rats were administered azoxymethane or saline for 6 weeks, after which a colonic anastomosis or sham operation was performed. CCPR, mucosal fatty acids, and tumor yield were analyzed at the anastomosis and proximal and distal colon sites at 15 and 23 weeks.

RESULTS: Diet, carcinogen treatment, and surgery all had significant effects on CCPR with omega-3 fats producing the lowest CCPR at all sites. There were fewer tumors (P < 0.02), including a marked reduction of anastomotic tumors in omega-3 fat-fed animals that was associated with a significant reduction of arachidonic acid in mucosal and tumor lipids.

CONCLUSIONS: Dietary omega-3 fat significantly reduced colonic CCPR and tumor yield, including at the site of anastomosis. Dietary omega-3 fats may be of value to patients after colorectal resection and anastomosis for cancer and warrant further testing.

Norat T, Bingham S, et al. Meat, Fish, and Colorectal Cancer Risk: The European Prospective Investigation into Cancer and Nutrition. J. of the National Cancer Institute, 2005;97(12):906-916

Background:
Current evidence suggests that high red meat intake is associated with increased colorectal cancer risk. High fish intake may be associated with a decreased risk, but the existing evidence is less convincing.

Methods:
We prospectively followed 478 040 men and women from 10 European countries who were free of cancer at enrollment between 1992 and 1998. Information on diet and lifestyle was collected at baseline. After a mean follow-up of 4.8 years, 1329 incident colorectal cancers were documented.

We examined the relationship between intakes of red and processed meat, poultry, and fish and colorectal cancer risk using a proportional hazards model adjusted for age, sex, energy (nonfat and fat sources), height, weight, work-related physical activity, smoking status, dietary fiber and folate, and alcohol consumption, stratified by center.

A calibration substudy based on 36 994 subjects was used to correct hazard ratios (HRs) and 95% confidence intervals (CIs) for diet measurement errors. All statistical tests were two-sided.

Results:
Colorectal cancer risk was positively associated with intake of red and processed meat (highest [>160 g/day] versus lowest [<20 g/day] intake, HR = 1.35, 95% CI = 0.96 to 1.88; Ptrend = .03) and inversely associated with intake of fish (>80 g/day versus <10 g/day, HR = 0.69, 95 % CI = 0.54 to 0.88; Ptrend<.001), but was not related to poultry intake.

Correcting for measurement error strengthened the associations between colorectal cancer and red and processed meat intake (per 100-g increase HR = 1.25, 95% CI =1.09 to 1.41, Ptrend = .001 and HR = 1.55, 95% CI = 1.19 to 2.02, Ptrend = .001 before and after calibration, respectively) and for fish (per 100 g increase HR = 0.70, 95% CI = 0.57 to 0.87, Ptrend<.001 and HR = 0.46, 95% CI = 0.27 to 0.77, Ptrend = .003; before and after correction, respectively).

In this study population, the absolute risk of development of colorectal cancer within 10 years for a study subject aged 50 years was 1.71% for the highest category of red and processed meat intake and 1.28% for the lowest category of intake and was 1.86% for subjects in the lowest category of fish intake and 1.28% for subjects in the highest category of fish intake.

Conclusions:
Our data confirm that colorectal cancer risk is positively associated with high consumption of red and processed meat and support an inverse association with fish intake.

Researchers at a Sydney hospital have found that fish oil can help patients with advanced bowel cancer. Scientists at Concord Hospital say that in a trial, bowel cancer patients who took fish oil with Omega 3 fatty acids respond better to chemotherapy.

Professor Stephen Clarke says cancers produce inflammatory markers in some patients that cause problems in the ability to tolerate chemotherapy. They also cause malnutrition.

But he says the anti-inflammatory and nutritional value of the fish oil has led to a better chance of successful chemotherapy.

"We've just completed a trial using fish oil supplements in this circumstance and what we found in that trial is that we were able to get patients to maintain their weight, we were able tor reduce some of these inflammatory markers and they tolerated the chemotherapy, when we treated them with it, fairly well," he said. "So that needs to be taken onto a randomised trial now."

Professor Clarke says the findings could also apply to people suffering from a range of cancers. He says more research will now be done. "There are a range of other things that we want to look at," he said.

"We want to look at just nutrition by itself, we want to look at nutritional programs combined with exercise, we want to alter the type of nutrition, you know fish oil-type nutrition versus just standard nutritional supplements.

"This is a fairly new field so there are a whole range of trials that can be undertaken."

Source: http://au.news.yahoo.com/060309/21/y64h.html