Smoking may have a devastating effect on gastrointestinal health

Smoking may have a devastating effect on gastrointestinal health and increase a person's risk of developing pancreatic and liver cancer, according to new research presented today at Digestive Disease Week 2005 (DDW). Furthermore, data from the Nurses' Health Study shows that meat intake and smoking play a part in significantly increasing a woman's risk of colorectal cancer.

DDW is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

"The effects of smoking on the respiratory system are well known and well documented through research," said Lee Kaplan, M.D., Ph.D., of Massachusetts General Hospital. "Recognizing that this high-risk behavior also hurts the digestive system is fundamental in preventing life-threatening cancers and improving overall health."

Smoking and Alcohol Use Associated with Markedly Earlier Age of Onset in Pancreatic Adenocarcinoma (Abstract 360)

With the link between smoking and pancreatic adenocarcinoma established, researchers from Evanston Northwestern Healthcare, an academic health system affiliated with Northwestern University, investigated the impact of smoking and alcohol use on the age of pancreatic cancer diagnosis and found that both play significant roles in the early onset of the disease.

Patients who were currently alcohol and tobacco users were diagnosed an average of 13 years earlier than individuals who had never used alcohol or tobacco, at median ages of 61 and 74 respectively for initial diagnosis. The data shows that smoking may have a more profound negative effect on the pancreas than alcohol, with current tobacco users being consistently diagnosed earlier than individuals who were current or former alcohol users. Study results also indicate that smoking and alcohol use may have a long-term effect on the pancreas, even after cessation. Individuals who had previously used tobacco and/or alcohol were diagnosed three to five years earlier on average than individuals who had never smoked or used alcohol.

Researchers studied records from 18,872 patients diagnosed with pancreatic adenocarcinoma in more than 350 hospitals nationwide, looking at alcohol and tobacco history as well as gender and age at diagnosis.

"Pancreatic cancer is one of the most difficult cancers to treat and is often fatal. Therefore, it is important for physicians to encourage patients to make healthy lifestyle choices to reduce their risk," said Randall Brand, M.D., of Evanston Northwestern Healthcare and senior author of the study. "Public health initiatives need to focus more strongly on curbing smoking and excessive alcohol use in order to curtail the growing mortality from pancreatic cancer."

Cigarette Smoking and Hepatocellular Carcinoma: A Case Control Study in the United States (Abstract M1661)

Although studies across the globe have examined the link between smoking and hepatocellular carcinoma (HCC), the most common form of liver cancer, little research has been done in North America, where liver cancer is on the rise. Researchers at the Indiana University School of Medicine found that a history of smoking significantly increased the risk of liver cancer. Investigators compared the records of patients diagnosed with HCC to chronic liver disease patients who did not have HCC. Results showed that people who have more than a pack per day over ten years were more likely to develop liver cancer than their non-smoking counterparts who suffer from chronic liver disease.

Researchers reviewed the records of 272 patients diagnosed with HCC between 1996 and 2004 from an electronic institutional database. Information was also pulled on 196 patients with chronic liver disease without HCC. Researchers investigated patient smoking history, alcohol consumption, diabetes, history of hepatitis and demographic data of patients with HCC and compared it to the chronic liver disease patients without HCC.

"As with other organs in the body, the effects of tobacco can have damaging consequences on the liver, significantly increasing the risk of developing liver cancer," said Paul Kwo, M.D., of Indiana University and lead study author. "Smoking cessation is one major way that patients can be proactive in preventing liver cancer, especially if they already suffer from chronic liver disease."

A Prospective Study of N-Acetyltransferase-2 Genotypes, Meat Intake, Smoking and Risk of Colorectal Cancer (Abstract 422)

Consumption of red meat and a history of smoking have both been associated with an elevated risk of developing colorectal cancer. Researchers at the Massachusetts General Hospital investigated the mechanisms behind this relationship and found that a person's risk of developing colorectal cancer is closely tied to N-acetyltransferase-2 (NAT2) enzymes, which transform certain compounds from red meat and cigarettes into carcinogens. A genetic variation of these enzymes is associated with more rapid production of carcinogens and may influence the impact of meat intake on cancer risk.

Researchers examined patients with NAT2 genotypes and found that while the modified enzyme alone did not increase the risk, women with rapid acetylator genotypes experienced a three-fold increase in their risk of developing colorectal cancer associated with an intake of more than half a serving of meat (beef, pork or lamb) per day compared with intake of less meat. Adding long-term smoking to the risk profile also significantly increased the likelihood of cancer, as the rapid NAT2 genotypes were associated with a nearly 18-fold increase in risk of colorectal cancer in women who were both long-term smokers and had reported high meat intake.

Taking into account age, family history, hormone and aspirin use and other dietary and lifestyle factors, researchers evaluated information on 32,826 women enrolled in the Nurses' Health Study, an ongoing set of investigations examining the risk factors of major diseases for women. Researchers compared 183 women with colorectal cancer to 443 control participants. The study further examined the NAT2 relationship to meat intake and smoking to women with slow acetylator genotypes and found no increased risk.

"This study provides a better understanding of how NAT2 genotypes may serve as a catalyst between meat intake and smoking and colorectal cancer," said Andrew T. Chan, M.D., MPH., of Massachusetts General Hospital and lead author on the study. "Based on this research, some women may be more genetically predisposed to the excess risk of colorectal cancer associated with meat intake and smoking. Although all women would probably benefit from smoking cessation and limiting intake of red meat, we may determine, with more research, that some women should be especially vigilant if they have a particular genetic background."