KYOTO, JAPAN Mycophenolate mofetil-based chronic immunosuppression is associated with a markedly lower risk of skin cancer during the first decade post kidney transplant, compared with alternative regimens aimed at preventing graft rejection, Dr. Irma Wisgerhof said at an international investigative dermatology meeting.
By 13 years post transplant, however, the squamous cell carcinoma risk in mycophenolate mofetil-treated organ recipients is equivalent to that of azathioprine, noted Dr. Wisgerhof of Leiden University (the Netherlands) Medical Center.
The mechanisms underlying these very different arcs of skin cancer risk are unclear. Azathioprine (Imuran) has a direct carcinogenic effect and causes accumulation of 6-thioguanine in cellular DNA. Azathioprine begins causing skin cancer in kidney transplant recipients early, and at a rate that remains steady over time. In contrast, mycophenolate mofetil (CellCept) prevents graft rejection by blocking immune surveillance; it suppresses both cellular and humoral immune responses, she explained.
Dr. Wisgerhof reviewed the experience with nonmelanoma skin cancer in 1,111 kidney transplant recipients who received their first donor kidney at the medical center in 1986-2006.
Through 2007, 6.7% of the patients developed a total of 102 invasive squamous cell carcinomas and 121 basal cell carcinomas. The cumulative incidence of nonmelanoma skin cancer was 3% after 5 years, 6% after 10 years, and 10% after 15 years of graft survival, she said.
The risk of squamous cell carcinomabut not basal cell carcinomavaried significantly depending upon the chronic immunosuppression regimen used.
The age- and gender-adjusted risk through the first decade post transplant was 88% lower with mycophenolate mofetil than with azathioprine-based regimens, and 65% less with cyclosporine- or tacrolimus-based regimens than with azathioprine-based immunosuppression, Dr. Wisgerhof said at a meeting of the European Society for Dermatological Research, the Japanese Society for Investigative Dermatology, and the Society for Investigative Dermatology.
Dr. Wisgerhof's study was supported by the Dutch Society of Dermatology and Venereology.
The risk of SCC varied depending upon the chronic immuno-suppression regimen used. DR. WISGERHOF