[CLINICAL RESULTS OF TWO PATIENTS WITH LATE RECURRENCE OF RENAL CELL CARCINOMA AFTER LONG TERM OBSERVATION WITHOUT TREATMENT].

Two patients with late recurrence of renal cell carcinoma were observed long term without treatment. Case 1 is an 83-year-old woman who underwent right nephrectomy at 57 years of age following a renal tumor diagnosis. Histopathological results revealed clear cell renal cell carcinoma, G2, pT1aN0M0. Pancreatic metastasis developed at age 71, and pancreatic tail excision was performed. A metastatic lesion appeared again at the head of the pancreas at age 74. The patient has been followed by observation only for 9 years without any new lesions. Tumor doubling time calculated from abdominal ultrasonography was 13.3 months.Case 2 is a 91-year-old male. At 78 years of age, right nephrectomy and inferior vena cava tumor embolectomy were performed for renal tumor. Histopathological results revealed clear cell renal cell carcinoma, G2, pT3bN0M0. Left adrenal metastasis appeared at age 84, and the patient has been followed for 7 years without new lesions. Tumor doubling time calculated from abdominal computed tomography (CT) images was 14.1 months.In both patients, no symptoms due to tumor recurrence ever appeared, and their activities of daily living (ADL) were maintained fairly well. In the case of solitary late recurrence in elderly renal cancer patients, observation may be a treatment option that avoids adverse effects and complications caused by treatment. In addition, it appears possible to predict the need for subsequent treatment by calculating the doubling time using several sequential CT images obtained after recurrence. If a new recurrent metastatic lesion appears or if the doubling time during a 2-to 3-year follow-up period is relatively short, however, new treatment should be considered without delay.