Solitary and multiple isolated metastases of clear cell renal carcinoma to the pancreas: an indication for pancreatic surgery.

Background: Isolated pancreatic metastases (isPMs) of clear cell renal carcinoma are rare. Most of them are solitary; some are multiple. The reported rates and the clinical implications of multiple isPMs from clear cell renal cancer vary. Therefore, the available literature was analyzed to shed light on the clinical significance of these extremely rare metastatic lesions.

Methods: A literature search brought to light 236 cases of isPMs (both solitary and multiple) from renal cell carcinoma. These were analyzed.

Results: A total of 12% of the metastases were synchronous with the primary tumor, and 88% were metachronous, occurring 10.0 +/- 6.5 years (mean +/- SD) after nephrectomy. A predilection for a specific part of the pancreas was not identifiable. The localization of the renal cell cancer (left or right kidney) did not have any effect on the site of the metastases. Seventy-four (39%) of the metastases to the pancreas were multiple (3.2 +/- 1.5). Their epidemiology did not differ from that of solitary metastatic lesions. Actuarial 3- and 5-year survival rates after radical resection were 78% and 78%, respectively, for multiple versus 75% and 64% for solitary metastases.

Conclusions: The epidemiological data do not support a direct local lymphogenous or venous spread from the primary tumor to the pancreas. They rather suggest a systemic spread. Because of the positive outcome, radical removal of both solitary and multiple metastases should be attempted in eligible patients.