Physicians should consider liver cancer screening for all patients with nonalcoholic fatty liver disease (NAFLD) and cirrhosis, according to a new clinical practice update from the American Gastroenterological Association.
Screening “should be offered for patients with cirrhosis of varying etiologies when the risk of hepatocellular carcinoma is approximately at least 1.5% per year, as has been noted with NAFLD cirrhosis,” wrote Rohit Loomba, MD, of the University of California, San Diego, and associates. Although patients with noncirrhotic NAFLD also can develop hepatocellular carcinoma, “[a]t this point, we believe that [the benefit of screening] is restricted to patients with compensated cirrhosis or those with decompensated cirrhosis listed for liver transplantation,” they wrote in Gastroenterology.
Liver cancer in NAFLD often goes undetected until it is advanced enough that patients are not candidates for curative therapy. Current guidelines provide limited recommendations on which patients with NAFLD to monitor for hepatocellular carcinoma, how best to do so, and how often. To fill this gap, Dr. Loomba and associates reviewed and cited 79 published papers and developed eight suggestions for clinical practice.
Patients with NAFLD and stage 0-2 fibrosis are at “extremely low” risk for hepatocellular carcinoma and should not be routinely screened, the practice update stated. Advanced fibrosis is a clear risk factor but can be challenging to detect in NAFLD – imaging is often insensitive, and screening biopsy tends to be infeasible. Hence, the experts suggest considering liver cancer screening if patients with NAFLD show evidence of advanced fibrosis or cirrhosis on at least two noninvasive tests of distinct modalities (that is, the two tests should not both be point-of-care, specialized blood tests or noninvasive imaging). To improve specificity, the recommended cut-point thresholds for cirrhosis are 16.1 kPa for vibration-controlled transient elastography and 5 kPa for magnetic resonance elastography.
Screening ultrasound accurately detects hepatocellular carcinoma in patients with cirrhosis who have a good acoustic window. However, ultrasound quality is operator dependent, and it can be difficult even for experienced users to detect mass lesions in overweight or obese patients. Thus, it is important always to document parenchymal heterogeneity, beam attenuation, and whether the entire liver was visualized. If ultrasound quality is inadequate, patients should be screened every 6 months with CT or MRI, with or without alpha-fetoprotein, according to the practice update.
The authors advised clinicians to counsel all patients with NAFLD and cirrhosis to avoid alcohol and tobacco. “Irrespective of NAFLD, the bulk of epidemiological data support alcohol drinking as a major risk for hepatocellular carcinoma,” they note. Likewise, pooled studies indicate that current smokers are at about 50%-85% greater risk of liver cancer than never smokers. The experts add that “[al]though specific data do not exist, we believe that e-cigarettes may turn out to be equally harmful and patients be counseled to abstain from those as well.”
They also recommended optimally managing dyslipidemia and diabetes among patients with NAFLD who are at risk for hepatocellular carcinoma. Statins are safe for patients with NAFLD and dyslipidemia and may lower hepatocellular carcinoma risk, although more research is needed, according to the experts. For now, they support “the notion that the benefits of statin therapy among patients with dyslipidemia and NAFLD significantly outweigh the risk and should be utilized routinely.” Type 2 diabetes mellitus clearly heightens the risk of hepatocellular carcinoma, which metformin appears to reduce among patients with NAFLD, cirrhosis, and type 2 diabetes. Glucagonlike peptide–1 receptor agonists and some thiazolidinediones also appear to attenuate liver steatosis, inflammation, degeneration, and fibrosis, but it remains unclear if these effects ultimately lower cancer risk.
It is unclear if obesity directly contributes to hepatocellular carcinoma among patients with NAFLD, but obesity is an “important risk factor” for NAFLD itself, and “weight-loss interventions are strongly recommended to improve NAFLD-related outcomes,” the experts wrote. Pending further studies on whether weight loss reduces liver cancer risk in patients with NAFLD, they called for lifestyle modifications, pharmacotherapy, or bariatric surgery or bariatric endoscopy procedures to optimally manage obesity in patients with NAFLD who are at risk for liver cancer.
The authors disclosed funding from the National Institute of Environmental Health Sciences, the National Center for Advancing Translational Sciences, the National Institute of Diabetes and Digestive and Kidney Diseases, the Cancer Prevention & Research Institute of Texas, and the Center for Gastrointestinal Development, Infection and Injury. Dr. Loomba disclosed ties to Intercept Pharmaceuticals, Bird Rock Bio, Celgene, Enanta Pharmaceuticals, and a number of other companies. Two coauthors disclosed ties to Allergan, AbbVie, Conatus Pharmaceuticals, Genfit, Gilead, and Intercept. The remaining coauthor reported having no conflicts of interest.
SOURCE: Loomba R et al. Gastroenterology. 2020 Jan 29. doi: 10.1053/j.gastro.2019.12.053.