The risk of developing lymphoma is markedly increased after solid organ transplantation e.g kidney, liver, heart or lung transplants. These lymphomas are medically termed Post-Transplant Lymphoproliferative Disorders or PTLDs.
How common is lymphoma after an organ transplant?:
Nearly 1 to 20% of people who receive a solid organ transplant develop a lymphoma. Lymphomas have also been reported (though less frequently) after bone-marrow transplants for other disorders.
Why does it happen?:
Post-transplant lymphomas are almost always related to infection by the Epstein Barr Virus (EBV). Infection by the Epstein Barr Virus causes a transformation of B-cells (a type of lymphocyte or white blood cell) which becomes cancerous. In normal individuals other cells of the immune system can tackle the EBV infection, but for organ transplants high doses of drugs that suppress the immune system must be administered. With nothing to control the infection, the chances of developing lymphomas increase.
What factors affect the risk of getting lymphomas after transplant?:
The two main factors that determine the chances of getting lymphoma are:
- How much immunosuppressive treatment is required the more the immunosuppression, the more the chances of EBV infection.
- The status of EBV serology of the recipient of the transplant if this individual has previously been infected by EBV the chances are that the body remembers the infection and the blood already has special proteins called antibodies that can identify and kill the virus. That can be tested by taking a blood sample.
How does post-transplant lymphoma behave?:
Post-transplant lymphomas are usually different from the usual Non-Hodgkin lymphomas. The cancer cells of this lymphoma are of a mixture of different shapes and sizes. While most patients have involvement mainly of lymph nodes, other organs are very commonly affected as well a phenomenon called extranodal involvement. These include the brain, lungs and the intestines. The transplanted organ can also get involved.
How is post-transplant lymphoma treated?:
Whenever possible, immunosuppressive treatment has to be reduced or stopped. In those who have small and localized disease, surgery or radiation may be attempted. If not, the first line of treatment is usually Rituximab, a monoclonal antibody that specifically targets lymphoma cells. Only when this fails is chemotherapy attempted. Chemotherapy is deferred until necessary as in partially immunosuppressed individuals, chemotherapy may further increase the risk of infections. In those who develop lymphomas after bone marrow transplants, donor leukocyte transfusions can be highly effective.
What are the outcomes with post-transplant lymphomas?:
In general, non-Hodgkin lymphomas occurring after organ transplants have a poorer outcome than other NHLs. Around 60-80% of the victims ultimately succumb to their lymphoma. However some individuals do fare a lot better and may get cured. Involvement of other organs, especially the brain, has a poor prognosis.