SAN FRANCISCO –
Doug Brunk/MDedge News
Dr. Alina M. Allen
Those are key findings from a community cohort study with up to 21 years of follow-up, which one of the authors, Alina M. Allen, MD, discussed during a press briefing at the annual meeting of the American Association for the Study of Liver Diseases.
“NAFLD is the most common chronic liver disease in the Western world,” said Dr. Allen, a gastroenterologist at the Mayo Clinic, Rochester, Minn. “It affects one in four adults in the U.S. It is related to fat accumulation in the liver in people who are overweight or obese and can lead to cirrhosis and liver-related mortality. However, the most common cause of death in this population is not liver disease but malignancy and cardiovascular disease. There is a paucity of epidemiologic studies of extrahepatic cancer in NAFLD. It is not clear what types of cancers and how much higher their cancer risk is in reference to the general population.”
In an effort to determine the incidence of cancer diagnoses in NALFD, compared with controls, in a U.S. community, Dr. Allen and her colleagues drew from the Rochester Epidemiology Project to evaluate 4,791 adults diagnosed with NAFLD and 14,432 age- and sex-matched control subjects in Olmstead County, Minn., during 1997-2017. The researchers obtained corresponding Surveillance, Epidemiology, and End Results Program (SEER) rates as a quality check and used a regression model to assess the malignancy risk in NAFLD overall and by cancer type, age, sex, and body mass index. They recorded all new diagnoses of cancers that developed in both groups until 2018, for a total possible follow-up of 21 years, and they reported results in incidence rate ratios, a risk estimate similar to hazard ratios.
The mean age of the study population was 53 years, 53% were female, and the mean follow-up was 8 years with a range from 1 to 21 years. New cancers were identified in 16% of subjects with NALFD and in 12% of control subjects. The overall risk of malignancy was 91% higher in NAFLD subjects, compared with control subjects; there were higher rates in the NAFLD subjects for most types of cancers, but the largest increases were in GI cancers. The greatest malignancy risk was for cancer of the liver (RR, 3.24), followed by cancer of the uterus (RR, 2.39), stomach (RR, 2.34), pancreas (RR, 2.09), and colon (RR, 1.75). “Interestingly, the risk of colon cancer increased only in men but not in women,” Dr. Allen said. “These data provide an important hierarchical overview of the top most important malignancy risks associated with NAFLD that the medical community should be aware of.”
When the researchers looked for differences in age at cancer diagnosis between NAFLD and controls, they found that pancreas cancer occurred at a younger age among subjects with NAFLD. They also observed that colon cancer occurred at a younger age in men with NAFLD, but not in women with the disease. “What was most interesting to us was the assessment of cancer risk in NAFLD versus obesity alone,” Dr. Allen said. “Previous studies from the general population have linked obesity to a higher risk of cancer. Whether the presence of fatty liver disease would impact that risk has not been assessed. We showed that obesity is associated with a higher risk of cancer only in those with NAFLD, not in those without. If validated in independent cohorts, these findings could change our understanding of the relationship between obesity and cancer and the importance of screening for NAFLD – not only to risk-stratify liver disease but also for the risk of extrahepatic malignancy.”
Dr. Allen concluded her presentation by noting that findings from large population-based studies such as the Rochester Epidemiology Project “can offer important epidemiologic data regarding the biggest threats to the health of a community,” she said. “Such data increase awareness, enable appropriate counseling, and could inform screening policies. There is a signal in the fact that the GI cancers are increased [in NAFLD]. It’s an interesting signal that needs to be studied further.”
Dr. Allen reported having no financial conflicts.
Source: Allen AM. Hepatol. 2018;68[S1]: Abstract 31.