Primary and secondary liver cancer

The place where a cancer starts in the body is known as the primary tumour. A cancerous tumour is made up of millions of cancer cells and sometimes a few of these cells may break away. When this occurs, the bloodstream carries these cells to other parts of the body. If these cells settle in that part of the body, they can form a new tumour. If this happens it is called a secondary cancer or a metastasis.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. It affects the main cells of the liver called hepatocytes. Although occasionally it spreads to other organs, HCC is usually confined to the liver.

The most common type of cancer that spreads to the liver is colorectal cancer; however other common primaries resulting in secondary liver cancer include breast, pancreas, stomach, lung, or skin.

In a healthy liver, the hepatic artery provides half of the oxygenated blood to the liver with the portal vein supplying the rest. In the case where liver cancer is present, the tumours receive most of their blood supply from the hepatic artery (red supply in diagram below), leading to as little as 10-20% of healthy liver tissue being supplied by the hepatic artery. The remainder of healthy liver tissue’s blood supply comes from the portal vein (blue in diagram below). It is this that allows selective treatment of the liver tumours using microspheres therapy.

The liver and its function

The liver is located below the right lung, and is protected by the lower ribcage. It is an organ that is of critical importance to general health as all nutrients or minerals from digested food or drink enter the bloodstream from the stomach and intestine and pass through the liver. The liver breaks down these nutrients for use across the body. Adversely, toxins and waste that enter the bloodstream are also filtered out and processed so they may be excreted as urine or faeces. In effect, the liver can be seen as a “chemical factory” that separates the beneficial nutrients and potentially harmful toxins before processing these nutrients and toxins for use or excretion.

There are two blood supplies to the liver, the hepatic artery and the portal vein. The hepatic artery supplies oxygenated blood to the liver directly from the lungs. The portal vein provides oxygenated blood that has passed through the digestive system before reaching the liver, collecting the nutrients from food such as carbohydrates, proteins, fats, and vitamins. Through these nutrients, the liver performs five key functions:

  • Processes carbohydrates into either instant energy (glucose) or stored energy (glycogen)
  • Breaks down fats, carbohydrates, and proteins into usable nutrients
  • Stores vitamins, minerals, and sugar to be processed into usable nutrients as required
  • Makes many integral substances, such as proteins and cholesterol
  • Produces bile which breaks down fats through the small intestines