Stomach Cancer: Good News and Bad News

There's good news and bad news about stomach (gastric) cancer. The good news is that the overall incidence of this cancer has declined significantly. This is particularly encouraging because stomach cancer is the most common type of cancer in the world.

The not-so-good news is that while the overall rate is declining, the incidence of stomach cancer in young adults age 25 to 39 has increased 67 percent over the past three decades. This trend stands out because stomach cancer doesn't normally strike people until they're 65 or older.

Experts have identified a few possible reasons for this anomaly.

H. Pylori
In developing countries, 23 percent of malignancies are due to infections, including Hepatitis B and C, HPV, and H. Pylori.

H. Pylori is a bacteria that lives in the stomach. We generally contract H. pylori in childhood and it's caused mostly by poor living conditions, overcrowding, and eating salt and salt-preserved foods. H. pylori is spread through contaminated food and water, or by mouth-to-mouth contact.

About two-thirds of the world's population has H. Pylori in their stomach, although most of us never become ill as a result. H. Pylori is tough and can live in the acidic environment of the stomach where most bacteria cannot survive. The risk of developing cancer in the lower stomach (called non-cardia gastric cancer) is six times higher in people with H. pylori infection.

Scientists are not sure if there's a change in the age at which people are becoming infected, or if the declining rate of H. Pylori infections is changing.

Tobacco, diet, and lifestyle
In its World Cancer Report in 2003, the World Health Organization (WHO) reported that cancer rates could increase 50 percent to 15 million new cases by 2020, due mostly to an aging population and trends in smoking prevalence and unhealthy lifestyles. Tobacco smoking, which is on the rise in developing countries, is associated with an increase in relative risk for several types of cancer-including stomach cancer. This is of particular concern in central and Eastern Europe where people are starting to smoke at younger ages.

Experts generally attribute the overall decline in stomach cancer incidence to the increase in refrigeration, which allows people to store fish and meat without preserving them in salt. And, while the incidence of stomach cancer is on the rise in young adults, researchers point out the relative risk is still low: about .45 cases per 100,000 individuals.

Sources:

National Cancer Institute. "What you need to know about stomach cancer." Web. 15 October 2009.
http://www.cancer.gov/cancertopics/wyntk/stomach

Anderson, W.F., Camargo, M.C., Fraumeni, Jr J.F., Correa, P., Rosenberg, P.S., and Rabkin C. "Age-Specific Trends in the Incidence of Noncardia Gastric Cancer in United States Adults." Journal of the American Medical Association 303(17) (2010): 1723-1728. Web. 4 May 2010.
http://www.cancer.gov/newscenter/pressreleases/GastricCancer

World Health Organization. "Global cancer rates could increase by 50% to 15 million by 2020." Web. 3 April 2003. http://www.who.int/mediacentre/news/releases/2003/pr27/en/

National Cancer Institute. "H. pylori and Cancer: Fact Sheet." Web. 17 October 2006. http://www.cancer.gov/cancertopics/factsheet/risk/h-pylori-cancer