New Study Confirms Weight is a Major Cancer Risk Factor

Photo: Flickr/Kizette

The subjects of weight gain, the obesity epidemic, and their major impact on health are brought up so much these days that they're easy to tune out.  So, if a few articles and news reports here and there pass you by - on accident or on purpose - we understand.  But we won't let that keep us from continuing to write regularly about the topic because it's something we're passionate about here at CNiC.

Why?

That's simple.  Overweight really is one of the most important health issues of our time, and much like tobacco in the middle part of the last century - unless we make some big strides against today's weight problem, generations will experience a greatly decreased quality of life and greatly increased rates of conditions like heart disease, diabetes, stroke, and cancer.  By keeping the issue upfront in articles, journals, and on social media, we can help push for policy changes and shifts in public attitude that will help address the obesity epidemic - much like we did with tobacco.  We've seen some very small positive steps recently on the obesity front, but we need to keep up - and expand on - these efforts.  

A study out today further confirms why.  Building on results from previous studies, researchers with the London School of Hygiene and Tropical Medicine published an analysis in The Lancet showing that increases in weight raise the risk of 11 different cancer, including esophageal, colon, liver, gallbladder, pancreatic, breast (post-menopause), cervical, uterine, ovarian, and kidney cancers, as well as leukemia.  Even for those in the healthy weight range (BMI of 18.5 - 24.9; or someone 5' 9" weighing 125 - 168 pounds), an increase of just one BMI point, say from 23 up to 24, was linked to an increased risk of cancer.

The researchers also calculated the percent of specific cancers likely caused by being obese or overweight (figure).  Five percent of all breast cancers diagnosed after menopause were linked to weight, as well as 11 percent of all colon cancers.  Each of these cancers is quite common.  Less common - but still very important - cancers had much greater percentages linked to weight.

In an accompanying editorial, titled Obesity: a certain and avoidable cause of cancer, Peter Campbell of the American Cancer Society concludes:

"We have sufficient evidence that obesity is an important cause of unnecessary suffering and death from many forms of cancer, in addition to the well recognised increased risks of mortality and morbidity from many other causes. More research is not needed to justify, or even demand, policy changes aimed at curbing overweight and obesity."

We certainly agree.  It's time to act more forcefully for prevention.  Yet, even though disease prevention is increasingly listed as a public health priority, funding and political backing for prevention programs still often lag behind fields like treatment and diagnosis. If we are to truly make headway in the fight against obesity and other key risk factors, prevention needs funding and political will commensurate with its large potential to reduce future disease burden.

Evolution of the Science on Aspirin Use and Colon Cancer Prevention

Yesterday, we posted about a new analysis suggesting that long term aspirin use is likely to have an overall health benefit in the general population even when its side effects are taken into account.  At risk of being wonky, we wanted to follow up on that with a figure that shows the general evolution of the science on aspirin use and colon cancer prevention.  

Though it's the cardiovascular benefits that come to most people's minds when they think of reasons to take a daily aspirin, the Cuzick et al analysis shows that most of the benefits from regular aspirin use don't come from the prevention of heart attack and ischemic stroke, they actually come from the prevention of cancer - including colorectal, esophageal, and stomach cancer, and possibly breast, prostate, and lung cancer.  Of these, colorectal cancer is the most important, making up about a third of the total cancer and cardiovascular disease benefits of aspirin use.  

The figure below (full size PDF) shows the evolution of the evidence on aspirin and colon cancer prevention.  Though the science has taken a while to develop, the findings of a number of early positive studies have been confirmed in later studies, and it seems we're finally reaching a point where broad recommendations for daily aspirin use to prevent cardiovascular disease as well as cancer may become a reality.

An Aspirin a Day...May Have Overall Health Benefits

Photo: Flickr/JenR

The writing was on the wall a few years ago, but it seems that we may have finally reached a point

where the scientific evidence points pretty convincingly to the potential health benefits of long-term regular aspirin use outweighing the potential risks for most people. That's the conclusion of a new analysis appearing last week in the Annals of Oncology. 

While the heart attack and stroke benefits of aspirin use, especially in those at high risk of such events, has been accepted for years, the cancer prevention benefits have been slower to catch on - even though the evidence for colon cancer prevention alone has been quite convincing.

This new analysis confirms the cardiovascular benefits of aspirin use while solidifying its benefits in both preventing and lowering mortality for colorectal, esophageal, and stomach cancer - and possibly for breast, prostate, and lung cancer.

Bleeding is the main concern with regular aspirin use, and the analysis found - not surprisingly - that the risks of events such as bleeding strokes (hemorrhagic strokes) and GI (gastrointestinal) bleeding go up with regular use.

However, after looking at all the benefits and risks together, the researchers found that use of a daily 75 - 325 mg aspirin for 5 or more years starting between ages 50 - 65 years had overall positive benefits.

After 10 years of use, risk of cancer, heart attack, and stroke was 9 percent lower in men and 7 percent lower in women after 15 years. Lower rates of cancer made up the large majority of this benefit, with colon cancer by itself making up about a third of the total benefit from aspirin use. Taking the risks of bleeding events into account, the overall health benefit dropped to about 6 percent for men and women. Lower but still overall positive.

Of course there are still many unanswered questions about the best approach to aspirin use. Because risk of bleeding goes up with age, it's unclear at what age people should stop taking aspirin because the risks outweigh the benefits. Figuring out the best way to identify people at risk of bleeding issues is another important topic, as is the best dose to use. While there's good evidence that a low-dose baby aspirin provides most if not all the benefits of, and likely has fewer risks than, a higher dose 325 mg aspirin, there are not yet definitive studies that have looked at the issue.

While anyone interested in starting on daily aspirin should first talk with his or her doctor, the data are now clearer than they've ever been that such use is likely to have real and lasting health benefits for most people.

Related post: Evolution of the Science on Aspirin Use and Colon Cancer Prevention