There was a wide variety of presentations relating to the economics of cancer at the international Health Economics Association (iHEA) meeting in Dublin last month. Of the sessions that I attended, the most interesting fact that I was unaware of, is that the number 1 cancer in Japan is stomach (gastric) cancer. This lead me to think – What other countries have high prevalence of stomach cancer? Is it diet-related? And what can be done in terms of prevention?
Incidence of Stomach Cancer: It is not just Japan (31.1 new cases /100,000), other countries in the Far East like South Korea (41.4), China (29.9), and Mongolia (34) have very high incidence rates of stomach cancer. Global Map of Stomach Cancer can be found at the ‘Stomach’ tab in Global Cancer Map
There is also high prevalence of stomach cancer in other countries like Honduras (26.6), Guatemala (26.6), Peru (21.2) and Mali (20.3).
Causes of Stomach Cancer: According to Cancer Research UK , the causes of stomach cancer are multi-factorial and likely relate to age, diet, helicobacter pylori infection, tobacco and alcohol consumption, acid reflux and radiation exposure.
Diet: A diet high in very salty foods increases the risk of stomach cancer. In Japan, very salty pickled foods are popular. These foods are not typically eaten in other parts of the World and stomach cancer rates are therefore lower than in Japan.
Helicobacter pylori: Chronic bacterial helicobacter pylori infection is a known cause of stomach cancer. Over half the world’s population has had a helicobacter pylori infection but most do not get stomach cancer so other factors must also be at work. Diet and smoking may interact with helicobacter pylori to cause stomach cancer. The bacteria can cause an inflammatory condition called severe chronic atrophic gastritis (SCAG) and this can lead to stomach cancer.
Acid reflux: This occurs when acid from the stomach goes back up into the oesophagus (foodpipe). It can cause inflammation of the oesophagus (oesophagitis). Acid reflux may increase the risk of cancer in the upper part of the stomach closest to the oesophagus (gastric cardia).
What can be done?
Helicobacter pylori elimination – At iHEA and previously at *HTAi , Canadian researcher (Arianna Waye, University of Alberta) gave a presentation, based on a systematic review of economic evaluations, on the elimination of helicobacter pylori around the World. This review was based on 15 studies and concluded that: “It does not appear possible to generate a cost effective international guideline for the elimination of helicobacter pylori infection as a gastric cancer prevention strategy”. As such, this conclusion is based on concerns of transferability of findings derived from cost-effectiveness analyses across jurisdictions.
Screening for stomach cancer: In Japan, where stomach cancer is the most common cancer, a screening programme is used. Since the beginning of the 1960s, a nationwide screening program using barium double-contrast radiography (X-ray) combined with endoscopy. The screening programme has meant that people are more likely to be diagnosed with early stomach cancer and so can have it treated with surgery. But it is still not clear whether the screening reduces the number of people who eventually develop advanced stomach cancer. In 2008, the Asia-Pacific Working Group on Gastric Cancer state that “there is a paucity of quality data from Asia to lend support for screening for gastric cancer”.
In 2012 a Korean paper included a cost-utility analysis of stomach cancer screening program revealed that annual endoscopic screening from ages 50-80 years was the most cost-effective (CE Threshold = $19,162/QALY) for the male population. In the females, biennial endoscopy screening from ages 50-80 years was calculated as the most cost-effective strategy among the 12 screening alternatives.
Conclusion: Stomach cancer is an example of a cancer consisting of a ‘perfect storm’ of individual and environmental factors. At an individual level, one can reduce the risk of stomach cancer by limiting one’s salt intake and increase one’s non-starchy vegetables and fruit intake. Also, a revelation from my discussion with the Japanese contingent at iHEA was the fact that Japanese men endured high levels of stress in their life. Maybe that’s the reason why Japanese men have so many gastric ulcers, caused by helicobacter pylori that eventually lead to stomach cancer.