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.

Alcohol and Cancer Link Highlighted at Alcohol Policy Conference

AICR’s evidence clearly and consistently shows that alcohol is linked to increased risk for several different cancers, which is why I was eager to attend the 17th Annual Alcohol Policy Conference near Washington DC.

In a session focusing on the alcohol-cancer link, Robert Pezzolesi, of the New York Alcohol Policy Alliance, led off by citing an AICR survey on the relatively low level of US awareness (43%) of the link between alcohol and cancer risk (below).

Screen Shot 2016-04-15 at 11.50.24 AMLinda Bauld of Cancer Research UK spotlighted the problems facing the UK, which is experiencing historically high levels of alcohol consumption. She cited a very low level of awareness of the alcohol-cancer link (13%) in the UK. This was the unprompted figure, when respondents were asked to volunteer various cancer risks. But when respondents were specifically asked if alcohol was related to cancer – a methodology similar to AICR’s US survey – 53% were able to identify alcohol as a risk. Continue reading

Aspirin and Cancer Prevention: An Update

There are several recognized ways that you can reduce your risk of colorectal cancer, but is taking aspirin one of them? This week the US Preventive Services Task Force released their recommendations on aspirin, cardiovascular disease and colorectal cancer – a final take on their draft recommendations released last year.

After a review of the research, the task force recommends that 50 to 59 year olds who have a 10 percent or greater 10-year risk of cardiovascular disease and have no risk for bleeding take a low-dose of aspirin. For these individuals, they conclude, taking aspirin  five to ten years can reduce the risk for cardiovascular disease and colorectal cancer. Here, they graded the evidence a B, meaning that there is high to moderate certainty of a net benefit.

If you are between ages 60 to 69, taking aspirin should be an individual decision depending on  preferences and discussion with a health care professional, they write.

Last year we wrote about their draft recommendations, noting that AICR’s focus is on how diet, nutrition, physical activity and weight links to cancer risk, so we have no position on aspirin use and risk.Screen Shot 2016-04-13 at 11.01.09 AMWhatever your decision on aspirin, you should also know there is clear evidence that several healthy habits and a healthy weight link to lower risk. Many of these steps also reduce risk for heart disease.

Eating plenty of foods with fiber, limiting red meat and avoiding processed meats, exercising and staying a healthy weight all link to lower risk. AICR estimate that these lifestyle factors could prevent one of every two colorectal cancer cases every year.

Here are AICR’s key findings and the report on colorectal cancer.

Continue reading