Patients and methods  Patients receiving modified FOLFOX6 for metastatic colorectal cancer were double-blinded and randomized to receive additional treatment with Ca/Mg or placebo before and after the administration of oxaliplatin. The plasma and ultrafiltrable concentrations of platinum during the first and fifth cycles of treatment were determined using inductively coupled plasma spectrometry.

Results  Patients were randomized to receive Ca/Mg (Ca/Mg group, n = 17) or placebo (placebo group, n = 16) before and after the administration of oxaliplatin (85 mg/m²). The incidence of neurotoxicity after six cycles was not significantly different between the two groups. Blood concentrations of platinum at each time and the area under the curve were also not significantly different between the two groups. Furthermore, the response rate (RR) and disease control rate (DCR) did not differ significantly between the two groups (Ca/Mg group: RR 36%, DCR 73%. Placebo group: RR 40%, DCR 70%, P > 0.99). The median progression-free survival time was 9.2 months in the Ca/Mg group and 8.1 months in the control group; these survival times were not significantly different (P = 0.56).

Conclusion  These data are insufficient to conclude with any certainty that the administration of Ca/Mg is not neuroprotective; however, the administration of Ca/Mg may not have any influence on antitumor activity and the blood concentration profile of platinum in patients receiving oxaliplatin-based chemotherapy.