I read the interesting report by Rubins [1] about his patient with metastatic renal cell carcinoma who responded to human recombinant erythropoietin. The underlying mechanisms of the association between renal cell carcinoma and erythropoietin are still unknown. I describe a patient who developed a local recurrence of renal cell carcinoma while receiving human recombinant erythropoietin.

A 51-year-old man had left radical nephrectomy for renal cell carcinoma. The disease recurred 2 years later in his right kidney, and a partial nephrectomy was done. The patient was admitted to a hemodialysis unit, where he received dialysis three times per week. He received human recombinant erythropoietin (Eprex, Cilag, Switzerland) at 12 000 U/wk for the first 6 weeks and then at a maintenance dose of 4000 U/wk for 1 year. Control ultrasonographic examination 14 months after the initiation of hemodialysis showed a right adrenal mass. Recurrent tumor invading the right adrenal gland was detected during the procedure, and a right adrenalectomy was done. The patient is well 9 months after the adrenalectomy, and there is no evidence of tumor recurrence. He is still receiving human recombinant erythropoietin at 4000 U/wk.

Although both this patient and Dr. Rubin's patient had similar oncologic problems and were treated with human recombinant erythropoietin, they also differed in important ways. First, my patient was subject to the immunosuppressive effects of chronic renal failure and hemodialysis treatment. Second, Dr. Rubin did not state the type of the recombinant erythropoietin used in treating his patient. The difference between the products administered may also explain the dissimilar clinical patterns of renal cell carcinoma in these patients. Third, there may be basic differences in neoplastic behavior in the regression of metastatic renal cell carcinoma and that of recurrent cancer. If both tumors could be studied by molecular biological methods, important conclusions could be drawn about the response of renal cell carcinoma to human recombinant erythropoietin. I believe that human recombinant erythropoietin can be used as an alternative therapeutic tool in treating renal cell carcinoma, at least in some patients.