Causes of Non-Hodgkin’s lymphoma

Non-Hodgkin’s Lymphoma (NHL) is the cause of 5% of cancers in the UK, is considerably more common than Hodgkin’s disease and tends to occur at a later age than Hodgkin’s disease with a peak incidence in the age group 45-60 years. It is nevertheless an important disease in childhood accounting for 15% of all childhood cancer.

 

The topic of lymphomas is of particular importance because they are so responsive to therapies, potentially curable and their therapy has often paved the way for new methods of therapy for other malignancies.

 

With regards the aetiology (cause) of NHL, there is no one answer, but there are undoubtedly well established clues and predisposing factors. A viral link has been well demonstrated for two types of NHL: adult T-cell NHL is causally related to a viral infection by HTLV-1 retrovirus and the Burkitt NHL, so prevalent in African children, is causally related to infection by the Epstein Barr virus.

 

The HIV virus, associated with AIDS, predisposes to the development of a high grade NHL and with the longer survival of patients with AIDS, so a higher proportion of these individuals develop NHL.

 

Other viral associations have been made (e.g. Epstein Barr infection and Hodgkin’s) but are not well substantiated. Immunodeficiency in the form of congenital syndromes (of which the Ataxia telangiectasia syndrome and the Wiskott Aldrich syndrome are best recognised) leave the affected patient prone to the development of NHL , which is a common form of death in these patients. Patients who are immunosupressed by drugs (e.g. kidney transplant recipients) are also much more prone to develop NHL and all these data imply that the normal body (i.e. in the non-immunosuppressed state) monitors effectively for ‘rogue’ transformation of lymphocytes or that the immunosuppressed state predisposes to lymphocytes becoming malignantly transformed.

 

Patients with auto-immune disease are predisposed to develop NHL usually in the afflicted organs e.g. auto-immune thyroiditis tends to lead to the development of a high grade NHL of the thyroid and Sjogren’s syndrome also predisposes to a similar NHL development. Environmental factors also play a part in the incidence of NHL, although the size of the problem in terms of overall incidence is so far unquantified. Occupational exposure to pesticides such as the organophosphate insecticides and hair spray/dye solvents have been associated with a higher incidence of NHL.