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06-05-2016 | Colorectal cancer | News | Article

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Immune modulation may be key to ω-3 CRC chemoprevention

medwireNews: The anticancer effects of marine ω-3 polyunsaturated fatty acids (PUFAs) may differ by tumour immune subtypes, say researchers who show that high ω-3 intake reduces the risk of colorectal cancer (CRC) with high, but not low, density of FOXP3+ regulatory T cells.

Among 125,172 participants of the Nurses’ Health Study and the Health Professionals Follow-up Study who provided data on marine ω-3 PUFA intake, 2504 developed CRC during 2,895,704 person–years of follow-up. And of these, sufficient tissue for T-cell density analysis was available for 614 individuals.

The beneficial effect of marine ω-3 PUFA intake was limited to cancers with high infiltration of FOXP3+ T cells – the CRC risk was a significant 43% lower for individuals who consumed at least 0.35 g of marine ω-3 PUFAs per day than those with an intake below 0.15 g/day.

By contrast, high ω-3 intake was not associated significantly with CRC risk reduction among participants with a low tumour density of FOXP3+ T cells, nor in individuals with tumours enriched for other T-cell subtypes, such as CD3+, CD8+ or CD45RO+.

Using an in vitro assay, Andrew Chan, from Massachusetts General Hospital in Boston, USA, and colleagues showed that preincubation with versus without docosahexaenoic acid at doses ranging from 50–200 μM significantly reduced the immunosuppressive activity of regulatory T cells.

These findings support the hypothesis that the anticancer effect of marine ω-3 PUFAs on CRC is, at least partly, mediated through the immune modulation of regulatory T cells, they write in JAMA Oncology.

By Shreeya Nanda

medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2016

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