Three groups of patients were reviewed. Primary carcinomas were found in donors kidneys of 47 recipients. In 30 instances a tumor was present at harvesting. When a neoplasm was removed immediately pretransplantation or early posttransplantation there were no recurrences in 14 recipients. In another two instances, a tumor was not removed or was incompletely excised pretransplantation and both recipients died of metastases. Fourteen other patients received kidneys from donors in whom the opposite kidney had a malignancy. Thirteen remained tumor-free and one had allograft nephrectomy for rejection 3 months posttransplantation when a carcinoma was found. In 17 recipients an allograft neoplasm was not recognized at harvesting. In 9 it was discovered at graft nephrectomy an average of 3 months posttransplantation. In a tenth patient a hypoechogenic area, found on routine posttransplant ultrasonography, progressively increased in size and proved to be malignant. Another 7 patients developed metastases from renal carcinomas an average of 12 months posttransplantation. Preexisting carcinomas were found in 350 recipients. Seventy-one patients with incidentally discovered tumors had no recurrences no matter when nephrectomy was performed in relationship to transplantation. Of 279 patients with symptomatic renal tumors, 70 (25%) had recurrences, 63% of which occurred in patients treated < or = 2 years pretransplantation. De novo cancers were found posttransplantation in 256 recipients. Renal carcinomas were 4.6% of posttransplant cancers compared with 3% of tumors in the general population. In 222 patients their own diseased kidneys were involved, in 24 tumors occurred in the allograft, and in 10 cases the site was not stated. Development of neoplasia seemed to be related not to the immunosuppressive therapy but to the underlying cause of renal failure, especially analgesic nephropathy. A disproportionate number of carcinomas (15%) involved the renal pelvis, most likely because of prior analgesic abuse.
