The Aberdeen University research team found that the proportion of enzymes responsible for processing omega-3 fatty acids, compared to omega-6, was strongly associated with survival of patients with colorectal cancer.
“This is the first finding of the differential expression of these enzymes and the association with this outcome in colon cancer,” said lead researcher Professor Graeme Murray.
"Prior to this study we did not know that such a relationship existed between these enzymes and survival in bowel cancer,” he added.
The study measured the levels of various enzymes in the tumours of patients with bowel cancer. When the researchers analysed the amounts of CYP4A11 and CYP4F11 (the enzymes responsible for metabolising omega-6 and omega-3 fatty acids), they found that patients with higher relative amounts of CYP4A11 were less likely to survive.
Previous research found that CYP4A11 converts omega-6 fatty acids to molecules that promote tumour growth and cancer progression. CYP4F11 metabolises omega-3 fatty acids to compounds that inhibit tumour development.
"The molecules or 'metabolites' that arise from the breakdown of omega-3 - prevent tumour spread and we assume that with more of the enzyme that breaks down omega-3 there will be increased metabolites of omega-3, and this will limit tumour spread. The less a tumour has spread the better the outcome. The converse is true for omega-6 metabolising enzyme – such that a higher proportion of omega-6 metabolising enzyme compared to omega-3 could lead to a worse outcome for the patient,” explained Murray.
"Our findings are important because it highlights a new pathway for understanding survival from bowel cancer." Murray added.
The study concluded that that both CYP4A11 and CYP4F11 enzymes are actionable drug targets with possible future therapeutic applications in colorectal cancer.
Murray suggested next step would be “To understand why there is the differential expression in the cancers that have good outcomes compared with those that have a poorer outcome.”
He was keen to emphasise that the study did not examine any issues regarding dietary intakes of omega-3 versus omega-6 containing foods.
Therefore, no conclusion could be drawn regarding changing the relative amounts of the two fatty acids as a means of improving bowel cancer survival.
Nevertheless, current findings support those in the Shanghai Women’s Health Study (reported by NutraIngredients), which found that higher ratio of dietary omega-6 to omega-3 was associated with increased risk of colorectal cancer.
Source: British Journal of Cancer
Volume 116, Issue 12: pages 1612-1620. doi:10.1038/bjc.2017.135
“The differential expression of omega-3 and omega-6 fatty acid metabolising enzymes in colorectal cancer and its prognostic significance”
Authors: Abdo Alnabulsi, Rebecca Swan, Beatriz Cash, Ayham Alnabulsi and Graeme I Murray.