[Two cases of colorectal cancer presenting with periodic, transient elevation of serum iron due to hemolysis after chemotherapy including 5-FU].

The serum iron level reportedly shows transient elevation after chemotherapy in some cases. However, the cause of this phenomenon has not been clearly described. We report two cases of colorectal cancer whose serum iron level demonstrated recurrent elevation after chemotherapy. Both were advanced colorectal cancer cases with liver metastases, so we started chemotherapy with modified FOLFOX6+bevacizumab. After several courses, we changed the regimen to simplified LV5FU2+ bevacizumab in both cases. The serum iron level showed transient, periodical elevation irrespective of the therapeutic regimen. Additionally, indirect bilirubin also showed transient elevation, which was completely synchronized with the fluctuation of the serum iron level. These observations suggest that hemolysis is the main cause of periodic, transient elevation of serum iron level after chemotherapy including 5-FU.

[Two cases of colorectal cancer presenting with periodic, transient elevation of serum iron after chemotherapy including irinotecan].

It is known that the serum iron level shows a transient elevation after chemotherapy in some cases; however, the cause of this phenomenon has not been clearly described. We report two cases of colorectal cancer whose serum iron level demonstrated recurrent elevation after administration of irinotecan as a second-line chemotherapy. The transferrin saturation rate showed marked elevation together with serum iron. This fact indicates that the release of non-transferrin bound iron (NTBI) occurs and then, NTBI binds with transferrin immediately thereafter. Additionally, elevation of indirect bilirubin in case 1, and mild anemia in case 2 were observed after every course of chemotherapy. All these phenomena were synchronized with the fluctuation of the serum iron level. These observations suggest that the transient elevation of the serum iron was related with the release of the NTBI from red blood cells after chemotherapy including irinotecan.