Stomach cancer risk increased in smokers with a bacteria

  Article date: 2002/07/10,Study Looks at Smoking, H. pylori Infection Together

Researchers have found that people infected with a bacteria linked to stomach cancer who also smoke increase their risk of developing the disease, according to a study published in the International Journal of Cancer (Vol. 97, No. 4: 446-449).

Infection of the stomach lining with the bacteria Helicobacter pylori, or H. pylori, usually occurs in childhood. It is known to be a cause of stomach cancer.

This study is one of the first to look at how smoking increases the risk even more in people infected with these bacteria.

"This might not be a huge problem in the United States because stomach cancer has been decreasing, especially the type that’s related to the [H. pylori] infection," said Ann Chao, PhD, research scholar in epidemiology and surveillance for the American Cancer Society (ACS).

"But…it’s a big problem [outside the US] because stomach cancer is the second most common cancer in the world, especially in areas where the infection is common and smoking is increasing," she said.
Problem Has International Proportions

According to the ACS, stomach cancer is a major cause of cancer death worldwide. It is very common in certain Asian, Central European, Central American, and South American countries. Those countries are also places where H. pylori bacterial infection is common.

People tend to get infected as children and carry the bacteria throughout their lives. These individuals also tend to start smoking in their teen years, so both risk factors may be present over many years.

While some smokers and nonsmokers may never show signs of disease, in others H. pylori may lead to ulcers, precancerous lesions, or cancer.

Some experts believe the decline in stomach cancer in the US and other developed countries is due to better food storage techniques, less use of salted and smoked foods, and use of antibiotics.
Smoking Multiplies Risk

In the study, German researchers looked at 71 patients with stomach cancer and 363 patients with colorectal cancer (the control group). The patients were asked about their smoking habits, and they were tested for H. pylori infection

The researchers also looked for certain strains of H. pylori, called CagA positive, that are more strongly associated with cancer.

The study found that nonsmokers infected with H. pylori had more than twice the risk of developing stomach cancer than uninfected nonsmokers. But those who had the infection and also smoked had a seven times greater risk of having stomach cancer compared with people who neither smoked nor were infected with H. pylori.

Chao said it is too soon to make any general recommendations about whether smokers should be screened for H. pylori infection. Chao said she would like to see larger studies on this subject.

But, she said, this study adds to the message that smokers should quit.

"I think this is a really important message for the world because smoking is a risk factor that can be changed. It’s not like family history that can’t be changed," Chao said.

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