Liver and the effects of smoking
Smokers are known to be at a higher risk for developing a host of diseases commonly high blood pressure (hypertension), lung cancer and so on. Cigarette smoke is a toxic collection of more than 4000 chemicals including nicotine. Now there is increasing evidence that smoking may negatively impact the prevalence, severity, and clinical course of many types of long-term (chronic) liver diseases and represent a risk factor for liver cancer.
High blood pressure is a common disorder in the 40-60 year age group. Uncontrolled blood pressure can have devastating complications such as stroke and serious heart disease. Dr Sinoway, Director of the Penn State Clinical and Translational Science Institute, USA has recently published a study on how normal blood pressure is maintained by the body. He explains that "the human body has a buffering system that continuously monitors and maintains a healthy blood pressure" and "if blood pressure drops, a response called muscle sympathetic nerve activity (MSNA) is triggered to bring blood pressure back up to normal levels." A phenomenon called "baroreflex" helps in the autocorrection of blood pressure back to normal levels if the blood pressure gets too high. Growing evidence showing that this autoregulation by baroreflex mechanisms is hampered in smokers and is a probable mechanism by which blood pressure increases to abnormal levels causing hypertension. Secondly, smoking also causes cholesterol deposits in blood vessels further increasing heart attacks, stroke, etc.
Any insult to the liver in form of alcohol or viral hepatitis such as hepatitis B or hepatitis C or fatty liver leads to progressive inflammation, scarring which if uncontrolled culminates in end-stage liver disease or cirrhosis. There is enough evidence showing that smoking exacerbates this ongoing inflammation in the liver, thereby faster progression to end-stage cirrhosis. Liver biopsies have indicated that smokers had more inflammation and scarring of their livers than non-smokers and providing further evidence of the harmfulness of smoking.
Smoking increases the risk of many different cancers, including liver cancer. Smoking produces chemicals with cancer-inducing chemicals such as hydrocarbons, nitrosamine, tar and vinyl chloride. Cigarettes are a major source of 4-aminobiphenyl, a liver carcinogen which is a known causal risk factor for hepatocellular cancer (HCC) and the most common liver cancer. Smoking increases the risk of HCC in patients with viral hepatitis infections.
Taken together, the evidence is clear that smoking has a major role in progression to advanced cirrhosis and increased risk of primary liver cancer at a faster rate. Hence, it is extremely important to emphasize immediate cessation of smoking as soon as liver injury due to any insult is identified to further prevent the catalyst effect of smoking.
Dr Chandan Kumar
Senior Consultant & Lead Transplant Physician
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