An estimated 25% or so of people with chronic hepatitis C go on to develop severe outcomes such as liver cirrhosis or hepatocellular carcinoma (liver cancer). Numerous host, viral, and environmental factors contribute to this variable rate of disease progression, not all of which are fully understood.

In the April 2008 Journal of Hepatology, 3 hepatology experts reviewed environmental factors associated with accelerated liver fibrosis progression in chronic hepatitis C patients. They noted than these factors have been investigated in order to improve clinical outcomes, especially for "difficult-to-treat" patients who tend to respond poorly to interferon-based therapy.

Over the past decade, the authors wrote, "several studies have shown that a combination of HCV infection and high levels of alcohol abuse results in synergistic acceleration of liver fibrogenesis." In addition, they added, more recent data indicate that even light alcohol consumption may also worsen fibrosis progression.

Some studies have suggested that tobacco smoking may enhance histological activity in chronic hepatitis C patients, thereby promoting fibrosis progression, although this has been less extensively studied than alcohol. One recent study suggested that enhanced fibrosis associated with cigarette smoking may be due to cytokine changes triggered by low oxygen levels.

Finally, the authors continued, cannabis use is increasingly emerging as a novel factor linked to liver disease progression in patients with chronic hepatitis C. As previously reported, studies by co-author Christophe Hezode have shown that regular cannabis smoking is an independent predictor of both fibrosis and steatosis severity in HCV-infected patients.

In addition, they added, "experimental studies have shown that cannabinoid CB1 receptors enhance liver fibrogenesis and steatogenesis by distinct mechanisms, therefore strongly supporting epidemiological findings."

In conclusion, the authors wrote, "[P]atients should be informed of the deleterious impact of alcohol, tobacco and cannabis use, and should be offered appropriate support to achieve abstinence."

Department of Hepatology and Gastroenterology, INSERM U841, Groupe Hospitalier Henri Mondor-Albert Chenevier, Créteil F-94000, France; AP-HP, Groupe Hospitalier Henri Mondor-Albert Chenevier, Service d'Hépatologie et de Gastroentérologie, Créteil F-94000, France; Université Paris 12, Faculté de Médecine, Créteil F-94000, France.

3/28/08

Reference
A Mallat, C Hezode, and S Lotersztajn. Environmental factors as disease accelerators during chronic hepatitis C. Journal of Hepatology 48(4): 657-665. April 2008.