Cyclosporine

To the Editor: Dr. Kahan presents a comprehensive review on cyclosporine (Dec. 21 issue).¹ One of the most dreaded complications of prolonged immunosuppressive treatment is the increased frequency of malignant neoplasms associated with this mode of therapy. Since cyclosporine is usually given with other immunosuppressive medications such as azathioprine and prednisone, it is difficult to assess its specific role in mutagenesis. In contrast to Dr. Kahan's firm conclusion that “cyclosporine does not promote either in vivo or in vitro mutagenicity or tumor induction,” Shinozuka et al.² found that cyclosporine has a promoting action on the induction of lymphomas of both …