1. Cancers of the anogenital region in renal transplant recipients;Penn;Analysis of 65 cases. Cancer,1986
2. Why do immunosuppressed patients develop cancer?;Penn,1989
3. Post-transplant kidney cancers and skin cancers (including Kaposi's sarcoma);Penn,1991
4. Immunosuppression—A contributory factor in lymphoma formation;Penn;Clin Transplant,1992
5. Immunosuppression and opportunistic tumors: Do viruses play a role?;Penn,1992