Long-term neurotoxicity effects of oxaliplatin added to fluorouracil and leucovorin as adjuvant therapy for colon cancer: results from National Surgical Adjuvant Breast and Bowel Project trials C-07 and LTS-01.

BACKGROUND

Neurotoxicity from adjuvant treatment with oxaliplatin has been studied in patients with colorectal carcinoma in short-term studies, but, to the authors' knowledge, the current article is the first long-term assessment which reports the National Surgical Adjuvant Breast and Bowel Project (NSABP) investigation of whether excess neurotoxicity persists beyond 4 years.

METHODS

As part of a colorectal cancer long-term survivor study (LTS-01), long-term neurotoxicity was assessed in 353 patients on NSABP Protocol C-07 (cross-sectional sample). Ninety-two of these patients from LTS-01 also had longitudinal data and were reassessed 5 to 8 years (median, 7 years) after random assignment (longitudinal sample). Contingency tables compared cohorts, a mixed model compared neurotoxicity between treatments over time, and a Wilcoxon rank-sum test compared neurotoxicity between treatments (cross-sectional sample).

RESULTS

In the cross-sectional sample, the increase in mean total neurotoxicity scores of 1.8 with oxaliplatin was statistically significant (P = .005), but not clinically significant (a minimally important difference of 4 was reported at the long-term assessment). Patients who received oxaliplatin had increased odds of numbness and tingling in hands (odds ratio, 2.00; P = .015) and feet (odds ratio, 2.78; P < .001) versus patients who did not receive oxaliplatin. The magnitude of the oxaliplatin effect varied with time (P < .001) in the longitudinal sample, such that the oxaliplatin-treated group did not have significantly greater total neurotoxicity scores by 7 years.

CONCLUSIONS

At the long-term endpoint, there was no clinically significant increase in total neurotoxicity scores for patients who received oxaliplatin, but the specific neurotoxicities of numbness and tingling of the hands and feet remained significantly elevated for oxaliplatin-treated patients.