Catheter occlusion by calcium carbonate during simultaneous infusion of 5-FU and calcium folinate

The treatment of colorectal cancer with administration of a 2-h infusion of calcium folinate followed by a 24-h infusion of 5-fluorouracil (5-FU) is a standard therapy. Based on newly published data we have applied an infusion of both compounds, 5-FU and calcium folinate, mixed together in an ambulatory pump.

We report on a patient suffering from metastatic rectal cancer. After first and second line chemotherapy we started third line chemotherapy consisting of calcium folinate (1,000 mg) and 5-FU (4,000 mg) mixed together in a total volume of 240 ml in an ambulatory pump and administered over a period of 24 h. After a total of 11 applications the patient developed a port thrombosis resistant to lysis with urokinase. The blocked catheter was surgically explanted and the firm material inside was analyzed.

The material from inside the lumen of the catheter was analyzed using x-ray spectroscopy and a scanning electron microscopy. Both analyses confirmed that the isolated material is calcium carbonate.

This case and the results of the analyses are in accordance with the described problems and results published earlier. A physical and/or chemical in vitro compatibility of 5-FU and calcium folinic acid, without validated clinical data is not sufficient to use this mixture in routine clinical practice.