Immunosuppression ‐ A contributory factor in lymphoma formation

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Abstract
Intense immunosuppression is complicated by the development of various neoplasms, many arising in the immune system itself, mainly nonHodgkin's lymphoma (NHL's). This is shown by the evolution of 883 lymphomas among 5737 types of cancer, that arose in 5386 organ transplant recipients, reported to the Cincinnati Transplant Tumor Registry up to June 1991. If nonmelanoma skin cancer and in situ carcinomas of the uterine cervix are excluded, they comprise 22% of neoplasms seen in transplant patients, compared with 5% in the general population. Most NHL's are large cell lymphomas or immunoblastic sarcomas. Immunologically, most (86%) are of B‐cell origin. Most (70%) lesions are extranodal in distribution. They show a remarkable predilection for the brain. Four groups of patients are particularly prone to develop lymphomas: cyclosporine‐treated patients, OKT3‐treated patients, recipients of nonrenal organs, and pediatric recipients. There is a considerable overlap of patients in these four categories. Possible causes of the NHL's include oncogenic viruses; disturbed immune surveillance; chronic antigenic stimulation; impaired immunoregulation; carcinogenic effects of immunosuppressive agents; and genetic susceptibility to lymphomagenesis. Treatment includes drastic reduction or cessation of immunosuppressive therapy, surgical excision, local radiation therapy, antiviral therapy with agents such as acyclovir, immunostimulation with agents such as α‐interferon, and cancer chemotherapy.