The important thing here is the difference between primary and secondary liver cancer.

A primary liver cancer is a cancer that starts in the tissues of the liver itself.

Secondary liver cancer occurs when seedlings of tumour from a cancer which has started somewhere else in the body (the primary cancer) break away and spread, usually through the bloodstream, and reach the liver. The seedlings then form new growths in the liver which are called secondary liver cancers or metastases. The cells making up the liver secondaries will look like, and behave like, the cells of the original primary cancer - so, for example, cells from a lung cancer which reach the liver and produce metastases made up of lung cancer cells, not liver cancer cells. Most of the common types of cancer, including cancer of the lung, cancer of the breast and large bowel cancer (cancers of the colon and rectum) will often form liver secondaries.

Primary liver cancer is very uncommon in the United Kingdom (although it is much more frequent in some other parts of the world such as Southern Africa and South East Asia). In Britain less than a thousand new cases of primary liver cancer are diagnosed each year making up less than 1% of all new cancers. In this country most primary liver cancers develop in people who have a long history of cirrhosis of the liver.

Secondary liver cancers are much more common then primary cancers. It is estimated than at least 4 out of every 10 people who die from cancer will have liver secondaries.

Very often when people, or the media, are talking about this subject they don't make a clear difference between primary and secondary liver cancer. So you will sometimes read or hear about people who have 'liver cancer' when what is really meant is that they have secondary liver cancer from a growth that started somewhere else in the body.