Human Liver, largest internal organ of the human body. The liver, which is part of the digestive system, performs more than 500 different functions, all of which are essential to life. Its essential functions include helping the body to digest fats, storing reserves of nutrients, filtering poisons and wastes from the blood, synthesizing a variety of proteins, and regulating the levels of many chemicals found in the bloodstream. The liver is unique among the body’s vital organs in that it can regenerate, or grow back, cells that have been destroyed by some short-term injury or disease. But if the liver is damaged repeatedly over a long period of time, it may undergo irreversible changes that permanently interfere with function.

 The largest internal organ in humans, the liver is also one of the most important. It has many functions, among them the synthesis of proteins, immune and clotting factors, and oxygen and fat-carrying substances. Its chief digestive function is the secretion of bile, a solution critical to fat emulsion and absorption. The liver also removes excess glucose from circulation and stores it until it is needed. It converts excess amino acids into useful forms and filters drugs and poisons from the bloodstream, neutralizing them and excreting them in bile. The liver has two main lobes, located just under the diaphragm on the right side of the body. It can lose 75 percent of its tissue (to disease or surgery) without ceasing to function.

 Cases of primary liver cancer, an often preventable disease, have trebled in the last 30 years, figures suggest.

 While it is not uncommon for cancer to spread to the liver, Cancer Research UK statistics show incidents where it starts in the organ have risen sharply.

 Cases of cancer overall have increased over recent decades as people live longer and detection methods improve.

 But experts say hepatitis C infections, as well as alcohol and obesity, have helped fuel the spike in liver cases.

 Primary tumours frequently develop as a result of cirrhosis, itself associated with these risk factors.

 Hepatitis C is a virus spread by blood-to-blood contact. Prior to 1991, transfusions were the most common source of infection, but since screening was introduced the disease is most commonly spread among intravenous drug users.

 Matt Seymour, professor of gastronintestinal cancer at the University of Leeds, said: "We are seeing more patients with cirrhosis and, in turn, more patients with primary liver cancer.

 "This is likely to continue. There is a long delay between exposure to the risk factors and the onset of cancer.

 "It might take between 20 and 40 years for liver cancer to develop after infection with hepatitis C. So even if new cases of infection stopped, the number of cases would continue to rise for some years."

 Screening call

 Obesity is now thought to be one of the most common causes of liver disease, while cases of cirrhosis associated with excessive drinking are known to have soared in the UK in recent years.

 Caught early enough, some of the damage caused by liver disease can be reversed and the risk of cancer developing reduced.

 But many people with hepatitis C do not know they are carrying the virus: estimates suggest that while more than 250,000 people in the UK have been infected, eight out of 10 are unaware.

 The five-year survival rate for primary liver cancer is low, and Cancer Research UK says it is currently supporting a number of trials to improve the treatment of the condition.

 Imogen Shillito, of the British Liver Trust, said: "We know liver cancer is caused by years of liver damage, often from infection with hepatitis B or C, or regular excessive drinking.

 "But there are many interventions that can prevent liver cancer. In particular, if people at risk are screened for hepatitis B or C and are offered effective treatment before liver damage has set in, their risk of liver cancer drops dramatically.

 "We want to see the NHS diagnosing and treating liver disease at an early stage to prevent liver cancer developing and save lives."