The nation’s growing girth is being implicated in an alarming and rapid rise in cancer of the esophagus, one of the most deadly of all cancers.
The incidence of esophageal adenocarcinoma — cancers that usually form in the part of the esophagus closest to the stomach — has doubled in Canada in the past 20 years, research shows.
Gastroesophageal-reflux disease, or chronic heartburn, which sends stomach acid bubbling up into the lower esophagus, is a major risk factor, and acid reflux increases with increased belly fat.
According to a study published in the Canadian Journal of Gastroenterology, esophageal adenocarcinoma incidence increased by about four per cent a year for men and women from 1986 to 2006.
If the trend continues, researchers project that rates of esophageal adenocarcinoma will increase by 40 to 50 per cent over the next 15 years.
It’s unusual for cancer rates to change so dramatically. “A doubling over 20 years is quite incredible,” says Michael Otterstatter, a senior scientist and epidemiologist at the British Columbia Centre for Disease Control in Vancouver. Otterstatter led the study on esophageal cancer trends while working at the Public Health Agency of Canada.
The esophagus is the hollow, muscular food tube that extends from the mouth to the stomach. “Most of the new cases of esophageal cancer now are these adenocarcinomas in the lower esophagus,” Otterstatter said. Historically, the dominant ones occurred higher up the food pipe, so-called squamous cell carcinomas that have been linked with smoking and alcohol consumption.
“That’s completely flipped in men now,” Otterstatter said. Adenocarcinomas are now twice as common in men as squamous cell carcinomas, and the same phenomenon is beginning to occur in women.
Esophageal cancer is increasing throughout the developed world, and it has one of the lowest survival rates of any cancer. The disease claimed famed writer Christopher Hitchens two years ago.
When caught early, the five-year survival rate is up to 80 per cent. However, about half of all new cases are diagnosed in the most advanced stage, when the cancer has spread. Often the first sign of a problem is difficulty swallowing. “At that point there may already be a tumour in the esophagus of substantial size,” Otterstatter said.
Risk factors include obesity and Barrett’s esophagus, a condition where the tissues lining the esophagus become damaged, usually from chronic acid reflux, making them more susceptible to becoming cancerous.
This week, researchers from the Fred Hutchinson Cancer Research Center in Seattle reported that belly fat is more strongly associated with Barrett’s progressing to cancer than a person’s overall body-mass index, or BMI.
Abdominal fat has been linked with higher circulating levels of substances that cause inflammation, and chronic tissue inflammation is believed to play a role in the development of many types of cancer.
Diets high in red meat and saturated fats are risk factors for both types of esophageal cancer, Otterstatter said, while diets rich in fresh fruits and vegetables appear to have a protective effect.
Although esophageal cancer is “down the list” in terms of the most common cancers, “we’re still talking about almost 2,000 new cases in Canada every year, and almost the same number of deaths,” Otterstatter said. “It’s still a significant number of individuals.”
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