[Successful sunitinib treatment of a patient with Stauffer's syndrome].

Several potential biomarkers of response to targeted therapies are being evaluated in metastatic renal cell carcinoma (RCC) to improve drug development and to determine which patient may benefit the most from the different treatment options. Stauffer's syndrome is a paraneoplastic syndrome that presents with the elevation of hepatic enzymes without hepatic metastases in patients with renal cell carcinoma. Hereby we report the case of our patient who suffered from multiple peritoneal metastases of renal cell cancer accompanied by Stauffer's syndrome. During his course of disease, the change in the serum gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP) levels correlated well with the extent of metastatic spread. Hypertension, grade 2 hand-foot syndrome and hypothyreosis also developed in relation to the successful sunitinib treatment. These side effects are predictive biomarkers in patients responding well to sunitinib. As other potential causes of increased GGT and ALP were excluded, the elevation of these enzymes were attributed to Stauffer's syndrome. During treatment, magnetic resonance imaging (MRI) follow-up showed complete regression, while the serum GGT and ALP levels halved. In this case, besides the known biomarkers, changes in serum GGT and ALP levels correlated well with the regression of metastatic renal cell carcinoma. To our knowledge, this is the first case published in the medical literature to show GGT and ALP levels in Stauffer's syndrome as potential biomarkers.