A 2019 survey estimated that over a quarter or adults in England are obese – and more than a third are overweight. Obesity substantially raises the probability of diseases, such as diabetes, heart disease, stroke, high blood pressure and cancer. New research has revealed that viscerally obese patients have the lowest number of cancer-killing cells in their tumours, lowering their chances of survival.
A team of scientists led by Dr Melissa Conroy and doctor Joanne Lysaght from Trinity College Dublin’s School of Medicine, worked with blood fat and tumour tissue samples collected from oesophagus cancer patients.
The findings of the study showed that obese patients had a significantly lower count of National Killer cells; specialised white blood cells which act as the immune’s system defence barrier.
The researchers discovered an inverse correlation between visceral obesity and NK cells in tumours, such that viscerally obese patients have the lowest number of NK cells in their tumours.
Doctor Conroy said: “For the first time our team has shown that the most viscerally obese oesophageal and gastric cancer patients have the lowest number of crucial cancer-killing natural killer cells in their tumours, and our work has confirmed that visceral obesity in these patients has devastating consequences for the anti-cancer immune response.
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“The natural killer cells are pulled into the visceral fat of these patients by a protein called fractal king where they are altered and even depleted.
“Consequently, the cancer-killing immune cells cannot reach and fight the tumour in sufficient numbers.”
The study, published in the Journal of Immunology, also identified a biological pathway that can be targeted with drugs to reduce the migration of NK cells away from the tumours.
Researchers identified a protein – called Fractalkine – which they believe plays a key role in pulling NK cells into visceral fat and altering their activity.
The researchers said the findings provide hope that a new approach may one day make a difference by redirecting and reinvigorating the anti-cancer immune response.
Doctor Conroy added: “Importantly we have shown that the movement of natural killer cells to the visceral fat of such cancer patients can be significantly reduced by a drug targeting fractalkine.
“Although it takes considerable time to go from a discovery like this to bringing a new drug to patients, it is nonetheless very exciting that our work strongly suggests a therapeutic approach targeting the fractalkine pathway would have significant utility in redirecting and reinvigorating the anti-cancer immune response in these poor prognosis cancers.”
Oesophago-gastric cancers – meaning cancer of the stomach or the oesophagus – are a group of obesity-associated and inflammation-driven cancers with very low survival rates.
The five-year survival rates for both cancers are 20 percent and 32 percent respectively, mainly due to poor treatment response rates.
Furthermore, research shows that excess weight causes more cases of certain cancers than smoking.
Obesity is a condition of excess body fat that occurs when a person’s BMI is above 30.
At a basic level, the condition is caused by an energy imbalance; if the energy input from calories is greater than the energy output from physical activity, the body stores the extra calories as fat.
In most cases, this imbalance results from a combination or circumstances and choices; adults should get at least 2.5 hours of exercise per week, but globally, one quarter of adults aren’t active enough.
Furthermore, calorie dense processed foods and growing portion sizes are leading to passive overeating.
Genetic makeups also play a part, with studies showing a clear causal hereditary relationship to weight gain.
According to the Mayo Clinic, the three main lifestyle choices known to fuel obesity are unhealthy diet, drinking too many liquid calories, such as alcohol, and leading a sedentary lifestyle.