The causes

• Although the cause of most non-Hodgkin's lymphomas is unknown, research into this cancer is ongoing.

• Researchers are investigating whether certain conditions, such as the use of drugs which prevent rejection following an organ transplant, may make people more likely to develop lymphomas.

• Other risk factors include genetic changes, certain infections, exposure to radiation or chemicals and diseases of the immune system.

• Non-Hodgkin's lymphomas, like other cancers, are not infectious and cannot be passed on to other people.

The symptoms

• The first symptom of a non-Hodgkin's lymphoma is usually a painless swelling in the neck, armpits or groin.

• Excessive sweating or fever, especially at night

• Persistent itch all over the body

• Loss of appetite, weight loss and tiredness

• Children may develop a cough or breathlessness. Children may also complain of abdominal pain or you may notice a lump in your child's abdomen

If you or your child has any of the above symptoms you must have them checked by your doctor, but remember, they are common to many conditions other than non-Hodgkin's lymphomas and most people with these symptoms will not have a lymphoma.