Idiopathic cardiomyopathy, age, and suppressor-cell dysfunction as risk determinants of lymphoma after cardiac transplantation.

A review of lymphomas developing in recipients of cardiac allografts has yielded significant risk factors. Frequency varied strikingly according to original cardiac disease: lymphoma developed in 6 of 37 patients with prior idiopathic cardiomyopathy (I.C.M.) but in one of 54 patients with prior coronary-artery disease (C.A.D.). All patients who developed lymphomas were aged under 40. Combination of both risk factors (I.C.M. and age less than 40) produces a sub-group with a highly significantly increased risk of lymphoma. I.C.M., but not C.A.D., is characterised by a defect in mitogen-induced mononuclear-cell suppressor activity. It is postulated that defective regulation in the immune systems of younger patients under chronic alloantigen stimulation may allow lymphoid proliferation to proceed to lymphoreticular malignancy. Immunosuppressive agents such as azathioprine may exert a co-oncogenic effect.