Ferritin: a tumor marker expressed by renal cell carcinoma

Renal cell carcinoma (RCC) has been shown to secrete several hormones and biologically active substances that influence the host metabolism or induce paraneoplastic syndromes. Observation of anemia in 20% of patients with RCC and the spontaneous recovery of anemia following nephrectomy drew attention to the body iron metabolism. Ferritin was previously proposed as a tumor marker for RCC. In order to determine whether RCC cells actually produce ferritin, we studied ferritin levels in serum from peripheral and renal veins as well as from the tumor tissue and the healthy parenchyma from radical nephrectomy specimens of 22 patients with RCC. Ferritin levels both in sera and cytosols were measured by an enzyme immunoassay method. The mean serum ferritin level from the renal vein was 419.9 +/- 72.4 ng/ml, and it was 157.3 +/- 18.3 ng/ml from the peripheral vein (p < 0.05). Renal vein ferritin correlated with stage and had a significant impact on prognosis (p < 0.05). The mean cytosolic ferritin level of the cancer tissue was 705.6 +/- 56.9 ng/mg cytosol protein, whereas in the normal parenchyma it was 95.9 +/- 10.1 ng/mg cytosol protein. This was also highly significant (p = 1.15 x 10(-13)), suggesting that RCC cells probably express ferritin. As currently there exists no reliable tumor marker for RCC, the value of ferritin as a marker should be investigated further before drawing any clinical conclusions.