Jan. 25, 2008 (Orlando) -- There has been a dramatic rise in a common form of one of the deadliest cancers over the past two decades -- and the epidemic of obesity is at least partly to blame, researchers report.
The cancer, a type of esophageal cancer called adenocarcinoma, struck three times more people in 2002 than in 1986, says Timothy L. Fitzgerald, MD, director of surgical oncology at Lacks Cancer Center in Grand Rapids, Mich.
Meanwhile, there was a significant increase in average BMI (body mass index) during the same period, he says. A ratio of weight to height, BMI is commonly used to determine if a person is obese.
"We're seeing this huge increase in esophageal cancer coincidental to the rise in obesity," Fitzgerald tells WebMD.
The findings were reported at the annual Gastrointestinal Cancers Symposium.
2 Types of Esophageal Cancer
There are two main types of esophageal cancer. One type grows in the cells that form the top layer of the lining of the esophagus. These are called squamous cells, and cancer that starts there is known as squamous cell carcinoma. Smoking and drinking alcohol are two of the biggest risk factors.
Adenocarcinoma mainly affects the lowest portion of the esophagus, where it meets the stomach. Studies have shown that people who are obese, who have acid reflux, or who have Barrett's esophagus, a condition in which abnormal cells develop from long-term acid reflux, are more likely to get this form of esophageal cancer.
Regardless of the type of esophageal cancer, fewer than one in five patients will be alive five years after diagnosis, says William J. Blot, PhD, a cancer epidemiologist at Vanderbilt University School of Medicine in Nashville. Blot was one the first researchers to show that esophageal cancers were on the rise in the U.S.
Adenocarcinomas Take Over
As recently as 1975, three in four esophageal cancers were squamous cell cancers. But starting in 1996, adenocarcinomas took over, Fitzgerald says. Now, esophageal adenocarcinoma rates are rising faster than those of any other cancer, he says.
For the new study, Fitzgerald and colleagues tracked more than 7,300 cases of esophageal cancer that were reported to the Michigan tumor registry from 1986 to 2002. Results showed that overall, the frequency of esophageal cancer in the U.S. rose from four to five cases per 100,000 people per year.
Rates of esophageal adenocarcinoma rose from one to three cases per 100,000 people per year. White men were particularly affected, with rates increasing from 2.5 to 5.9 cases per 100,000 people per year.
In contrast, the number of cases dropped slightly among African-American women.
The researchers then looked at BMI trends in the state of Michigan from 1988 to 2006. They found that among whites, the average BMI rose from 25 to 28; among African-Americans, it increased from 27 to 30.
A BMI of 18.5 to 24.9 is considered normal weight. People are considered overweight if their BMI is 25 to 29.9, and obese if they have a BMI of 30 or more.
Avoiding Weight Gain May Help
Blot says that avoiding excessive weight gain and obesity may lower your risk of developing esophageal adenocarcinoma, although that remains to be tested in a formal study.
Action is clearly needed, he tells WebMD.
"If current trends continue, with roughly a doubling in incidence rates every 10 years, esophageal carcinoma will become one of the leading causes of cancer death in the not too distant future," Blot says.