There are several types of esophageal cancer, all of which form in the muscular tube where food passes from the throat to the stomach. The most serious forms of the disease are squamous cell carcinoma and adenocarcinoma.
Studies have shown smoking and drinking can contribute to the risk of squamous cell esophageal cancer, but statistically that may not be the case with Hitchens. Most of the time, white middle-aged men succumb to adenocarcinoma, which can be caused, in part, by acid reflux, according to doctors.
The National Institutes of Health (NIH) reports that 16,470 new cases of the disease were reported in 2009.
"It's one of the worst cancers and the reason is because it's so easy to metastasize," said Dr. Fritz Francois, assistant professor at New York University and a gastroenterologist who does research on esophageal cancer. "If you think about it as a tube and on the outside is a network of blood vessels and lymph nodes."
Those age 65 years or older are at the highest risk of getting esophageal cancer, according to the NIH. Men are three times as likely to develop the disease, especially those who drink more than three alcoholic beverages a day; smokers, too are at high risk, and the combination of the two increase the chances of developing the disease exponentially.
The main function of the cells in the esophagus are to protect the rest of the body.
"Not only do the cells protect against the stomach acid coming up, things move forward and we swallow a lot of things we shouldn't," said Francois. "If you are a smoker, although the smoke goes to the lungs, anything that coats your mouth, you can swallow and expose the cells to carcinoma."
"Think about them like pancake layers, one stacked on top of the other,' said Francois. "There are about 40 of them stacked on top to form a barrier on the esophagus."
The rate of squamous cell carcinoma is highest in African American men – about 28 cases out of 100,000 as compared to 3 out of 100,000 in the general population.
The second major type of esophageal cancer is adenocarcinoma, which occurs in the gland-forming cells near the swallowing tube's junction with the stomach. That disease is associated with acid reflux damage. About 2 to 3 in 100,000 will get this type of esophageal cancer; the risk is double -- 5 in 100,000 -- for white men, according to Francois.
As the tube approaches the stomach –- at the gastroesophageal junction –- the cells of the esophagus transition to the cells of the stomach and become more column-like. It is there that adenocarcinoma strikes.
"Those cells stand taller and their function is different," he said. "That lining has other specialized cells that work like a team, like a basketball guard that makes acid cells and other protein."
In a condition called Barrett esophagus, abnormal cells develop to protect the lower esophagus from acid, increasing the risk for adenocarcinoma. Most people don't know they have it, according to Francois.
Symptoms for both squamous cell and adenocarcinoma include difficulty in swallowing, weight loss, pain swallowing or anemia. In some cases, patients vomit up blood. "At that point, the thing has been there for a while, and our chance of picking it up at an early stage is rare," he said.