Lymphoma is a cancer of the lymphatic system. The lymphatic system is made up of a series of vessels and glands, known as lymph nodes. These are spread throughout your body, much like your blood vessels.

Non-Hodgkin's lymphoma is the most common type of lymphoma (the other main type is Hodgkin's lymphoma). Over 9,700 people in the UK are diagnosed with non-Hodgkin's lymphoma each year. 

High-grade and low-grade

There are many subtypes of non-Hodgkin's lymphoma, but they can all be put into one of two broad categories:

• high-grade or aggressive non-Hodgkin's lymphoma is where the cancer develops quickly and aggressively
• low-grade or indolent non-Hodgkin's lymphoma is where the cancer develops slowly, and you may not experience any symptoms for many years

Who is affected

Non-Hodgkin's lymphoma is associated with ageing, as the chances of developing the condition increase as you get older. The average age at diagnosis is around 65.

Increasing number of cases

For reasons that are not understood, the rate of new cases of non-Hodgkin's lymphoma has been slowly but steadily rising for the last 50 years. The rate of increase in the UK is around 4% a year.

If the occurrence of non-Hodgkin's lymphoma continues to rise at the current rate, it is estimated that it will be as common as breast or lung cancer by 2025.

Outlook

Despite their names, high-grade non-Hodgkin's lymphoma is easier to treat than low-grade non-Hodgkin's lymphoma. Cure rates depend on individual circumstances and the subtype of the lymphoma, but an average of 60% of people with high-grade non-Hodgkin's lymphoma are cured.

The difficulty with low-grade non-Hodgkin's lymphoma is that it does not cause symptoms until it is well advanced, by which time it is often too late to cure. However, it is possible to control symptoms for many years.

What is cancer?

The body is made up of millions of different types of cells. Cancer happens when some of the cells multiply in an abnormal way. When cancer affects organs and solid tissues, it causes a growth called a tumour to form. Cancer can occur in any part of the body where the cells multiply abnormally.