Behind The Headlines: Questions about AICR’s Stomach Cancer Report

We’ve just released our latest systematic review of the global literature linking diet, weight and physical activity to an individual cancer; this time, it’s stomach cancer in the spotlight, and there’s some striking news.

The report’s three major findings – that alcohol, processed meat and obesity increase the risk for stomach cancers – are entirely new. Much of the research makes important distinctions that previous research didn’t, and there’s more to know about stomach cancer risk than easily fits into a headline. Here, we answer questions about some of the nuances that have emerged.

Two of these three new risk factors apply to distinct types of stomach cancer, cardia and non-cardia. What’s the difference?

Stomach cancer is actually an umbrella term encompassing lots of different subtypes.

The two main types are classified according to the part of the stomach where the cancer starts: cardia and non-cardia. They appear to have different causes.

The cardia region is the top of the stomach, where it joins the esophagus. Cancer that develops here is called cardia stomach cancer. The non-cardia region is the lower area of the stomach, so non-cardia stomach cancer means a tumour in the lower part of the stomach.

Non-cardia stomach cancer is more common in Asia and is associated with Helicobacter pylori bacterial infection.

The link with processed meat is new and that shows effects on one type, correct?

Processed meat increases the risk for non-cardia stomach cancer, but there is no association with cardia stomach cancer

Why would a daily hot dog increase a person’s risk of this cancer type?

Non-cardia stomach cancers, which occur in the lower part of the stomach, can happen because the stomach can hold food for up to five hours during digestion, exposing the stomach lining to carcinogens present in some foods.

It could be that the preservatives added to processed meats, such as nitrates and nitrites, can react with the meat during digestion to form carcinogenic N-nitrosamines. These damage the stomach lining and cause lesions, which can lead to cancer.

And being overweight increases the risk of cardia stomach cancer, but there is no association with non-cardia cancer?

Cardia stomach cancer is thought to be mainly caused by damage to cells at the top of the stomach by the acid associated with gastroesophageal reflux disease (GERD).  Being overweight or obese makes GERD more likely.

Having 3 or more alcoholic drinks a day applies to both cancer types. Why would alcohol increase risk?

There are a number of reasons why alcohol can increase the risk of stomach cancer. Alcohol is metabolized into acetaldehyde, which is a carcinogen. It also causes damage to cells (through oxidative stress, which occurs when there are not enough antioxidants to neutralise metabolic damage) and can interfere with cell growth and the cell life cycle, which predisposes cancer. Alcohol also makes it easier for other carcinogens, such as from tobacco, to enter the cells.

Alcohol-blog_imageThe finding with alcohol applies to men and women?

Yes. But the risk is most apparent in men, as well as smokers and ex-smokers.

The 2007 report said that salt was a cause of stomach cancer; today’s report shows that this evidence is now weaker. Yet it does say that “foods preserved by salting” are a cause of stomach cancer. Clarify?

The report found strong evidence that certain salt preserved foods are a cause of stomach cancer: foods preserved by salting such as meat and fish, and salt-preserved vegetables.  Research showed that the more people eat of these foods the greater their chance of developing stomach cancer.

The evidence on these foods comes primarily from studies conducted in Asia, particularly Japan and Korea. Many of the traditional foods in these countries are preserved by salting and fermentation.

How might salt-preserved foods increase the risk of stomach cancer?

Experimental research has shown that salt damages the stomach lining and causes lesions, which, if left to develop, can become stomach cancer.

Infection with H. Pylori bacteria also damages the stomach lining, and is made worse in the presence of salt. H. pylori infection is relatively common in parts of Asia and is also an independent cause of stomach cancer.

10-recommendations-infographicYet limiting salt intake still remains an AICR Recommendation for Cancer Prevention?

The evidence on salt in the Western diet is now inconclusive – this could be because of difficulties in measuring total salt. Evidence on total salt intake, from studies worldwide, didn’t show a strong link with stomach cancer.

A diet in high-sodium foods is not a great idea, but more research needs to be done to examine the impact of the kind of high-salt foods commonly eaten in the West. The 2015 Dietary Guidelines recommend Americans consume less than 2,300 milligrams of salt per day, and AICR recommends limiting the salty foods in your diet.

Study: How to save money while preventing childhood obesity

Taxes on sugary drinks and unhealthy food advertising to kids may save more than $30 in health care costs for every dollar spent to implement, suggests a new study published this month.

Childhood obesity rates are nudging upwards, which means more kids are at risk for obesity in adulthood. With this extra weight comes increased risk for cancer, heart disease, and diabetes, as well as the high costs of health care that come with these diseases.

The new study used previous research to analyze the cost effectiveness and impact on childhood obesity of 7 proposed interventions. Six of the interventions aimed to prevent weight gain in youth while one involved surgical treatment of obesity. With the help of policy makers and other experts, study authors estimated the the effect of each intervention among the US population over the 10 years spanning 2015 to 2025.

Overall, five strategies were found to decrease incidence of childhood obesity (see chart) with three saving more in healthcare costs than they cost to implement.

Obesity cost effectivenesssOne strategy was a tax on sugary beverages. The proposed tax, translating to 12 cents for a can of soda, would prevent an estimated 576,000 children from being obese and save $30 for every dollar it cost to enact.

Another effective strategy was to create nutrition standards for school snacks, fundraisers and other foods sold outside of school meals. This would prevent an estimated 345,00 cases of childhood obesity, saving about $4.50 for every dollar it costs.

Nutrition standards for school meals was found to prevent the most cases of childhood obesity — approximately 1.8 million cases — yet this strategy cost about 60 cents more to implement than it would save in healthcare costs.

These results demonstrate the importance and feasibility of prevention measures to reduce childhood obesity, note the authors. The sugar sweetened beverage tax and taxing advertising would also provide revenue that would offset the costs of other prevention efforts, such as nutrition standards for school meals. Future studies are needed to assess the cumulative impact and costs of these interventions.

This study was funded by The JPB Foundation, The Robert Wood Johnson Foundation, the Donald and Sue Pritzker Nutrition and Fitness Initiative, and the Centers for Disease Control and Prevention.

AICR Award Highlights, New Research in Obesity and Cancer

How can bariatric surgery and a mom’s smartphone link to reduced cancer risk?

These studies were among the winners of the AICR research poster competition, announced yesterday at the annual Obesity Week conference. Obesity is associated with increased risk of a number of cancers, including ovarian, endometrial, and colorectal. The winners, awarded support by AICR, included three early investigators and two student prizes.

In no particular order, here are highlights of this year’s winners for outstanding posters. Congratulations to all. Note: these poster findings are not yet published and have not yet gone through the peer-reviewed process.

Ǻsa Anveden, MD PhD University of Gothenburg, Sweden

AvendenBariatric surgery is one obesity-treatment option and previous research suggests decreased risk of cancer following surgery. This surgery may reduce the risk of cancer in obese women, suggests the finding of this study.

Anveden and her team followed over 4,000 obese people (70% women) for up to 26 years to look for cancer incidence. About half the participants had undergone bariatric surgery, and they were matched to a group of obese controls who received usual care. Continue reading