Purpose: The randomized, multicenter, phase III protocol C-07 compared the efficacy of adjuvant bolus fluorouracil and leucovorin (FULV) versus FULV with oxaliplatin (FLOX) in stage II or III colon cancer. Definitive analysis revealed an increase in 4-year disease-free survival from 67.0% to 73.2% in favor of FLOX. This study compares neurotoxicity between the treatments.
Patients and methods: Neurotoxicity was recorded for all patients using standard adverse event reporting. Patients at select institutions completed a neurotoxicity questionnaire through 18 months of follow-up.
Results: A total of 2,492 patients enrolled onto C-07 and 400 patients enrolled onto the patient-reported substudy. Mean patient-reported neurotoxicity was higher with oxaliplatin throughout the 18 months of study (P < .0001). During therapy, patients receiving oxaliplatin experienced significantly more hand/foot toxicity (eg, "quite a bit" of cold-induced hand/foot pain 26% FLOX v 2.6% FULV) and overall weakness (eg, moderate weakness in 27.4% FLOX v 16.2% FULV). At 18 months, hand neuropathy had diminished, but patients who received oxaliplatin experienced continued foot discomfort (eg, moderate foot numbness and tingling for 22.1% FLOX v 4.6% FULV). Observer-reported neurotoxicity was low grade and primarily neurosensory rather than neuromotor. Sixty-eight percent in the FLOX group v 8% in the FULV group had neurotoxicity at their first on-treatment assessment. Time to resolution was significantly longer for those receiving oxaliplatin, and continued beyond 2 years for more than 10% in the oxaliplatin group.
Conclusion: Oxaliplatin causes significant neurotoxicity. It is experienced primarily in the hands during therapy and in the feet during follow-up. In a minority of patients the neurotoxicity is long lasting.