Where body fat is carried can predict cancer risk

Study finds men with over 40in waist and women with over 35in waist are more at risk of cancer as waist size is as good at predicting cancer risk as BMI | via Cancer Research UK 

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Scientists have found that carrying fat around your middle could be as good an indicator of cancer risk as body mass index (BMI), according to research published in the British Journal of Cancer . 

The study combined data from around 43,000 participants who had been followed for an average of 12 years and more than 1,600 people were diagnosed with an obesity-related cancer.

The study found that adding about 11cm to the waistline increased the risk of obesity related cancers by 13 per cent. For bowel cancer, adding around 8 cm to the hips is linked to an increased risk of 15 per cent.

Being overweight or obese is the single biggest preventable cause of cancer after smoking and is linked to 13 types of cancer including bowel, breast, and pancreas.

Full reference: Freisling et al. Comparison of general obesity and measures of body fat distribution in older adults in relation to cancer risk: meta-analysis of individual participant data of seven prospective cohorts in Europe. British Journal of Cancer. (2017) 116, 1486–1497

Read more at Cancer Research UK

Obesity linked to heightened risk of certain cancers

Obesity is strongly linked to the risk of developing certain major cancers, according to a re-analysis of research published in The BMJ | OnMedica | BMJ

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Links between obesity and cancer risk are strongest for 11 cancers related to digestive organs and hormones, says the review. Obesity could also be linked to other cancers, but the quality of the evidence is not sufficiently strong to draw those conclusions yet.

Obesity prevalence has more than doubled over the past 40 years, and the evidence to date suggests that it is linked to a heightened risk of developing particular cancers, but methodological flaws in some published studies have weakened the strength of the associations found.

To better gauge the quality of the evidence and the strength of these associations, the researchers comprehensively reviewed published studies looking at obesity and cancer risk.

From among 204 reviews that analysed obesity measurements, such as body mass index (BMI), weight gain, and waist circumference, and the risk of 36 cancers, 95 included continuous measures of obesity.

Only 13% of the associations for nine cancers were based on strong evidence, meaning the results were statistically significant and excluded bias.

Strong associations were found in studies that looked at heightened risk of oesophageal, bone marrow, colon (in men), rectal (in men), biliary tract system, pancreatic, endometrial (in premenopausal women), and kidney cancers.

Read more via OnMedica

Link to the research: Kyrgiou M, Kalliala I, Markozannes G, et al. Adiposity and cancer at major anatomical sites: umbrella review of the literature. BMJ 2017;356:j477. DOI: 10.1136/bmj.j477

How obesity contributes to, blocks treatment of pancreatic cancer

ScienceDaily. Published online: 6 July 2016

Massachusetts General Hospital (MGH) investigators have discovered the mechanism by which obesity increases inflammation and desmoplasia — an accumulation of connective tissue — in the most common form of pancreatic cancer.

In their report published online in Cancer Discovery the researchers describe how interactions among fat cells, immune cells and connective tissue cells in obese individuals stimulate a microenvironment that promotes tumor progression while blocking the response to chemotherapy. They also identify a treatment strategy that may inhibit the process.

Read the full report here

Read the original research abstract here

Short and sweet: Why the government should introduce a sugary drinks tax

Sugar tax could prevent 3.7 million cases of obesity over next decade

A 20% tax on sugary drinks in the UK would prevent 3.7 million people becoming obese over the next decade, a report predicts. Cancer Research UK and the UK Health Forum worked out the likely impact of the tax on eating habits.  Their report said such a tax would also save the NHS £10m a year by 2025.

Full report: Short and Sweet: Why the government should introduce a sugary drinks tax

BBC report: Sugary drinks tax ‘would stop millions becoming obese’

Severe obesity prior to diagnosis limits survival in colorectal cancer patients evaluated at a large cancer centre

Daniel, C.R. et al. British Journal of Cancer (2016) 114, 103–109

Background: In contrast to the consistent evidence for obesity and colorectal cancer (CRC) risk, the impact of obesity in CRC patients is less clear. In a well-characterised cohort of CRC patients, we prospectively evaluated class I and class II obesity with survival outcomes.

Methods: The CRC patients (N=634) were followed from the date of diagnosis until disease progression/first recurrence (progression-free survival (PFS)) or death (overall survival (OS)). Body mass index (BMI) was calculated from reported usual weight prior to diagnosis. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated in models adjusted for clinicopathologic, treatment, and lifestyle factors.

Results: Over a median follow-up of 4 years, 208 (33%) patients died and 235 (37%) recurred or progressed. Class II obesity, as compared with either overweight or normal weight, was associated with an increased risk of death (HR and 95% CI: 1.55 (0.97–2.48) and 1.65 (1.02–2.68), respectively), but no clear association was observed with PFS. In analyses restricted to patients who presented as stages I–III, who reported stable weight, or who were aged <50 years, obesity was associated with a significant two- to five-fold increased risk of death.

Conclusions: In CRC patients evaluated at a large cancer centre, severely obese patients experienced worse survival outcomes independent of many other factors.

View the full article via British Journal of Cancer

Economic costs of obesity

The UK Health Forum and Cancer Research UK have published Tipping the scales: why preventing obesity makes economic sense.  The report found that rising rates of obesity and overweight could lead to 700,000 new cancer cases in the UK, as well as millions of new cases of type 2 diabetes, coronary heart disease and stroke. This would cost the NHS an additional £2.5 billion a year by 2035 over and above what is already spent on obesity related disease.  The report calls on the Government to introduce a 20p per litre tax on sugary drinks as well as a 9pm watershed ban on TV advertising of junk food as part of a comprehensive children’s obesity strategy.

Additional links: Cancer Research UK press release    BBC News report

How exactly does obesity cause cancer? Three leading theories

From Cancer Research UK

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Image source: Cancer Research UK

1. The oestrogen connection

One of the strongest links between obesity and cancer is an increased risk of breast and womb cancers in women who are overweight or obese after the menopause, and this relates to higher oestrogen levels.

While the link to women’s cancers is stronger, there’s also data suggesting that obesity-related changes in sex hormones can play a role in men’s cancers too. There’s evidence that, while rare,breast cancer in men is linked to increased oestrogen caused by excess body fat. Obesity is also linked to higher rates of aggressive prostate cancer, but it’s unclear if changes in oestrogen from fat cells play a role, or whether  it could be down to changes in testosterone, the male sex hormone.

2. Metabolic chaos

The chemical processes going on constantly throughout the body – collectively known as metabolism – are complicated and tightly controlled, relying on a finely tuned web of information flowing between cells and organs. But the chemical signals produced by fat cells means that obesity can cause a major upset to this balance, and this is thought to be another way it makes cancer more likely.

There’s also substantial laboratory evidence of a link: lots of data showing that as cancer cells react to both insulin and insulin-related growth factors, they become harder to kill, and divide more quickly.

3. Inflammation

As people become obese, and more fat cells build up in their tissues, specialised immune cells (called macrophages) are called to the scene, possibly to clear up dead and dying fat cells. But as macrophages carry out their clean up job, they also release a potent cocktail of chemicals called cytokines that summon other cells to help them out. The number of macrophages in obese fatty tissue can be substantial – they can account for as many as four in 10 cells. This ultimately creates a condition called chronic inflammation – and this is another way that obesity is thought to fuel the development of cancer. And it’s been shown that obese people tend to have higher levels of inflammatory cytokines in their blood.

The evidence that inflammation is linked to cancer is damning. Many chronic inflammatory diseases (such aspancreatitis and Crohn’s disease) can increase a person’s risk of cancer. And cancers caused by infections are also characterised by chronic inflammation.

Read the full blog post via Cancer Research UK