Isolated Late Metastasis of a Renal Cell Cancer Treated by Radical Distal Pancreatectomy

A 53–year-old man underwent right nephrectomy for a locally advanced renal cell carcinoma with concomitant resection of a solitary metastasis in the right lung. Ten years later, he presented with haematochezia caused by a tumour in the tail of pancreas, invading the transverse colon and the greater curvature of the stomach. The tumour was radically resected, and histological examination revealed a solitary metastasis of the previous renal cell carcinoma. This case illustrates a rare indication for pancreatic resection because of pancreatic metastasis.


INTRODUCTION
At the time of diagnosis approximately 23% of all renal cell carcinomas are metastatic1. Most patients present with multiple metastases, solitary metastasis being rare. The value of surgical treatment in such cases, i.e. nephrectomy plus excision of one or more metastases, in uncertain, but it is sometimes carried out for lack of satisfactory alternatives. Solitary late recurrence, defined as metastasis occurring 10 years or more after diagnosis of the primary renal tumour is also uncommon and has an unfavourable prognosis. Pancreatic metastases are much less common than pulmonary metastases but can be the presenting feature of a kidney neoplasm2.

CASE REPORT
A 53-year-old man presented in 1982 with a solitary right pulmonary nodule on a routine chest X-ray and  The patient underwent en-bloc tumour excision with distal pancreatectomy, splenectomy, partial gastrectomy and left hemicolectomy. Histologically a metastatic lesion was found consisting of a moderately differentiated clear cell carcinoma. Comparison of this pathology specimen with the original renal tumour revealed an almost identical tumour. The postoperative course was uneventful and the patient was discharged on the tenth postoperative day. At 6 months follow-up, he was well without evidence ofrecurrence on abdominal or thoracic CT scan.

DISCUSSION
Metastatic renal cell carcinoma, whether synchronous or metachronous, has a poor prognosis, five-year survival rates range from 0 to 19%3, and survival beyond 10 years is rare4'5. In selected series, combined resection of the primary renal tumour and of a solitary lung metastasis has produced a 5-year survival rate of 25-35% Late recurrence of a renal tumour after curative resection is uncommon, but it can occur after diseasefree intervals of several years. Petersen found 23 reported cases of recurrent renal carcinoma after 10 to 37 years3. Most of these recurrences were in the lung, and recurrence in the pancreas, colon or stomach has not been described. Prolonged survival can follow surgical excision of the late metastasis.
Although our patient presented initially with a synchronous pulmonary metastasis, he did well for 10 years after radical tumour surgery. Again, despite the local extension of the pancreatic metastasis, radical excision was both feasible and well tolerated by the patient. Abnormal tumour-host interactions may be responsible for the unusual sites and intervals ofrecurrence observed. Removal of a solitary late metastasis can be followed by further disease-free survival of up to 17 years7.
Operative treatment is seldom indicated for pancreatic metastases although there are some reports for isolated metastasis of melanoma Seventeen cases of renal carcinoma presenting with pancreatic metastasis have been reported 2,9,10,11, and this can be an occasional indication for pancreatectomy.

Invited Commentary
Metastasis to the pancreas is distinctly uncommon, being described at autopsy in only 3-5% of patients with generalized malignancies1'2. Usually the primary tumour is bronchogenic carcinoma, breast carcinoma or melanoma, but metastases have been reported from a wide variety of primaries such as the thyroid, colon and kidney3'4. Renal cell carcinoma, in particular, can behave in a variable and somewhat unpredictable manner. Although most patients with this disease die within a year, up to 20% may have periods of slow tumour growth or stability lasting many years6, during which time metachronous carcinoma or metastasis to unusual sites may occur despite radical resection of the initial tumour7. In a review of 506 patients with renal cell carcinoma, Mc Nichols et al. found that among the 158 patients who survived more than 10 years, 11% had late recurrence in the form of metastases8. As with the case of Dr. Barras, 25% of all renal cell carcinoma patients first present with metastasis 9,10, usually to the lungs, lymph nodes, liver and bone. The site of metastasis seems to influence survival and response to treatment. In a study of 181 cases, Maldazys et al. noted that patients with metastasis limited to the lung parenchyma survived longer than those with metastasis to other single or multiple organs.
Metastatic involvement of the pancreas is often part of widespread nodal and visceral involvement11, while solitary metastasis to the pancreas is rare, with an incidence of 1-3,/012 Metastasis to the ampulla of Vater is even more uncommon; very few cases have been reported so far, as shown by Tsao et al. in the present report. Most of these patients presented with symptoms of gastrointestinal bleeding and/or jaundice, whereas half those with pancreatic metastasis may be asymptomatic6. The patient of Dr. Barras who presented with haematochezia secondary to colonic erosion was unusual.
The five-year survival rate of patients with untreated metastatic renal cell carcinoma is poor, usually less than 13% 13 With surgical removal of pulmonary metastases, Tolia  However, a recent review ofthe world literature covering sixteen patients with resection of renal metastases to the pancreas endorsed the value of operative treat-ment14. In general, the factors associated with a favourable prognosis after resection of such metastases include: 1) A long interval from the time of resection of the primary tumour, 2) evidence of a solitary lesion on radiographic examination, even if multiple nodules are found at operation, 3) demonstration of extensive necrosis in the resected speci-men5'14. The extent of pancreatectomy should be dictated by the location of the lesion and the need for an adequate margin of resection. If the disease is limited to the pancreas (or ampulla) or even if it is locally spreading but technically resectable (as in the patient of Dr. Barras), a radical surgical strategy is justified. It is not clear why Dr. Tsao and her colleagues elected to perform a transduodenal excision of the ampullary metastasis in their second patient rather than a formal pancreatoduodenectomy which might conceivably have prevented local recurrence.
As adjuvant irradiation and/or chemotherapy does not seem to prolong the survival of patients with pancreatic metastases, including renal secondaries3, and because the outlook is generally dismal, it seems that radical surgery should be offered to these rare patients.