The Skinny on Esophageal Cancer: Obesity, Tobacco, and Screening

While the rates of many cancers have remained stable over the past decade, the rate of some esophageal cancers has been rising, and the main culprit is likely the epidemic of overweight and obesity.

Squamous cell cancers of the esophogous , a cancer type largely caused by smoking, have remained stable. But adenocarcinomas of the esophagus (including the gastric-cardia) have been rising steeply in recent years, and aside from tobacco use, most of its main risk factors are tied directly or indirectly to weight .
Directly, obesity can induce inflammation throughout the body as well as increase levels of insulin and related hormones, both of which have been linked to an increased risk of cancer. Indirectly, obesity, is also closely tied to severe acid reflux (also known as GERD) and Barrett’s esophagus, a condition where the make-up of the cell lining of the esophagus changes. Obesity increases pressure on the abdomen and stomach, which may be part of the process by which it increases risk of reflux (see figure), which in turn can increase the risk of Barrett’s esophagus.


Adenocarcinoma of the esophagus generally arises from the changes that mark Barrett’s esophagus. Yet , only a relatively few individuals with reflux or Barrett’s esophagus go on to develop cancer. This points to a role for both lifestyle and genetic factors in the transition from Barrett’s esophagus to esophageal cancer. At present, we don’t have good indicators of who will progress from Barrett’s esophagus to esophageal cancer.

Currently, screening with endoscopy (a lighted tube inserted into the esophagus) is often recommended for those with sever reflux or Barrett’s esophagus to try to catch cancers early when they’re most treatable, or even find pre-cancers that can be removed before they turn into cancer. Unfortunately, such tests have yet to be shown to be effective. Individuals with Barrett’s esophagus who have regular endoscopies don’t live longer than those who do not have regular endoscopies. In part, this is because the test isn’t as precise as we’d like. Estimates are that only 10 percent of those with suspicious test results in a high risk population (like those with reflux) actually have cancer.

Even though the science of screening for esophageal cancer is still developing, there are important steps we can take right now that can reduce the risk of the disease, and they are increasingly important as rates of the disease overall keep increasing and more than half of all cases are diagnosed at a late stage. The most promising approach is to keep acting on what we already know: Continue to combat tobacco use and take steps to stem the national (and worldwide) epidemic of overweight and obesity.

Vaccination Against Hepatitis B Prevents Liver Cancer

As reported in the New York Times, San Francisco has launched an important public health campaign to promote vaccination against the hepatitis B virus which causes liver disease and liver cancer (story). This campaign is important for several reasons. Infection is usually silent and the impact on disease is many years after initial infection.

Prevention programs for cancer take different durations for the benefit to be observed. Vaccination programs offer one insight to the time frame of intervention and the ultimate reduction in cancer incidence. For cervical cancer prevention with human papilloma virus (HPV) vaccine, the current U.S. Center for Disease Control (CDC) recommends vaccination for women between ages 13 and 26; the benefit of this prevention will be observed many years hence. Hepatitis vaccination programs in Africa and Asia offer further illustration of these points. In the Gambia, a program launched in 1986 aims to evaluate the effectiveness of childhood vaccination with hepatitis B and current estimates are that the final outcome of reduced hepatocellular carcinoma in adults should be measurable from 2017 onwards. In Asia with nationwide hepatitis B vaccination implemented in Taiwan in 1984, results at 10 years show significant reduction in hepatocellular carcinoma in children. Clearly many years of follow-up are required to demonstrate protection of adults, though this outcome is implied by results to date.

The etiology of some 18 per cent of cancers worldwide can be linked to chronic infections due to agents such as Helicobacter pylori, human papillomaviruses (HPV), Hepatitis B, Hepatitis C, Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), human herpes virus 8 (HHV-8), and Schistosoma haematobium, with the proportion of all cancer due to infections being much higher in developing countries (26 per cent, compared to 7.7 per cent in developed countries). The current burden of cancer in the developing world is dominated by infection, once smoking is accounted for. Of 10.8 million new cases of cancer worldwide (2002 figures), those caused by infectious agents are estimated as: H. pylori 5.5 per cent (mainly stomach, and lymphoma); HPV 5.2 per cent (mainly cervix, and ano-genital, mouth, pharynx); HBV and HBC 4.9 per cent (liver); EBV 1.0 per cent (nasopharynx, Hodgkin lymphoma and Burkitt lymphoma), HIV and HHV-8 0.9 per cent (Kaposi sarcoma, non-Hodgkin lymphoma) and other less common agents including schistosomes, HTLV-1, and liver flukes, less than 0.5 per cent. More than 25 per cent of cancer incidence in developing countries could be avoided if infectious causes of cancer were prevented. Successful vaccination programs have the potential to reduce cancer incidence and mortality; for example, Taiwan’s HBV vaccination program was initiated in 1984, and impressively high coverage rates (up to 97 per cent in 2004) have led to a consistent decline in hepatocellular cancer rates. However, a recent study by Chang et al. underscores the importance of a multi-pronged approach. Though Taiwan has seen a decrease in the incidence of hepatocellular cancer in children since initiation of the vaccination program (from 0.54 to 0.20 per 100,000 before and after the program), vertical transmission, vaccine failure, and the lack of hepatitis B immunoglobulin injection has affected program effectiveness and public health impact.

Given the burden of infection with the virus in Asian Americans in California, estimated at 10% it is not too early to begin a major campaign such as that instituted in San Francisco.

Video - "Workplace Wellness: Good for Business, Great for You"

On his recent trip to Syndney, CNiC's Graham Colditz, MD, Dr PH, spent some time at the Cancer Council discussing the benefits of workplace wellness and some strategies that can make such programs successful (video).