The viruses of Hepatitis C, of Epstein-Barr and the HIV increase the risk to suffer from lymphomas
100 experts from all over the world, meeting in Barcelona, point out the need to study the relation between infections by viruses and the lymphomas. The lymphoma (a cancer which affects the white corpuscles in blood) is one of the tumours that increase most in developed societies. In Catalonia, the new cases increase 6% every year.

The relation between some infections, above all by viruses, and the development of some types of cancer is more and more accepted. The evidence of the implication of the human inmunodeficiency virus (HIV), the hepatitis C and Epstein-Barr viruses in the appearance of lymphomas is growing.

The last meeting of the international consortium InterLymph (International Lymphoma Epidemiology Consortium), celebrated in Barcelona and which gathered around 100 specialists from 20 institutions and 15 countries, has reached the conclusion that one of our priorities must be to define the exact relation between different infections and the lymphoma.

The lymphoma, a growing pathology

Lymphomas are some fifteen different tumours which afect the lymphatic system, and which have very variable prognosis and survival. The importance of this illness and the type of most common lymphoma change significantly in different countries: it depends on, above all, the most typical infections found in each geografical area.

The alteration of the inmunity system is a very important risk factor to develop a lymphoma. Those infected by HIV who suffer from AIDS are 300 times more likely to have one than the ones who do not have the virus, and the people who have had a transplant have between 6 and 30 times more probability to suffer from this cancer.

The lymphoma is one of the tumours that occurs more and more frequently in developed societies: in Catalonia, the increase has been 6.1% anually since 1980. At the moment we still do not know the reason for this increase; a better diagnosis, changes in life style, the population’s ageing or the presence of inmuno-supressing illnesses are thought to be some of the causes.

Lymphomas are much more frequent among men than among women (21.9 new cases out of 100,000 inhabitants and year in Catalonia and 14.9 new cases out of 100,000 inhabitants and year, in Europe). It is the fifth most frequent cancer among men, and the third most incident tumour among women. 13,000 new cases are diagnosed every year in Spain (7,100 men and 5,800 women). It is estimated that 1 out of every 66 men and 1 out of every 111 women will have developed a lymphoma at 64 years of age.

The Epstein-Barr virus and lymphoma

A work led by the Institut Català d’Oncologia (ICO), published this month in the magazine International Journal of Cancer, shows that the study of the proteins implied in the division of the Epstein-Barr virus (EBV) may be a good indicator of the risk to develop a lymphoma.

This infection is very frequent in population –more than 90% of the people are infected– but in most cases it is latent. If it is a late infection (at adolescence) it causes infectious mononucleosis, also known as the ‘kiss illness’, which can turn into a non- Hodgkin lymphoma. The virus is also implied in other lymphomas, in which it activates irregularly, especially in patients with inmunitary deficiency. For this reason, the analysis of the proteins implied in the activation of the EBV could be used as a tool to evaluate the risk to have a lymphoma: ‘In general the virus multiplies very slowly because the inmunity system makes its division slower. If, for some reason, the virus starts dividing without control, it can cause a lymphoma’, as explained by Sílvia de Sanjosé, of ICO’s the Epidemiology and Cancer Register Service.

The study has been carried out comparing the standard of expression of the proteins related to the proliferation of the Epstein-Barr virus in 1,085 patients with lymphoma and 1,153 control individuals. Apart from ICO, the Verge de la Cinta Hospital in Tortosa, and centres from Holland, Germany, the Czech Republic, France, Italy and Ireland have taken part in it.

Interlymph

The consortium InterLymph was created six years ago, promoted by the National Institute of Cancer of the U.S.A and the WHO, to have better studies of the epidemiology of the lymphomas. InterLymph has stablished other priorities besides the study of the infections:

To look for genetic variations which increase the liability to the lymphoma.
To analyse the relation between surrounding factors (the exposure to toxic elements at work, tobacco, alcohol, ultraviolet rays, hair dyes…) and cancer.
To take these studies to developing countries.