Variability of Oxaliplatin-Induced Neuropathic Pain Symptoms in Each Cycle and Its Implications on the Management of Colorectal Cancer Patients: A Retrospective Study in South Western Sydney Local Health District Hospitals, Sydney, Australia

Oxaliplatin-induced neuropathic pain limits treatment compliance. However, the variability of neuropathic pain symptoms in each cycle for individual patients and the impacts on treatment compliance remain untested. Data from 322 adult patients who received oxaliplatin-based chemotherapy were extracted based on pattern of chemotherapy, adverse events, and patient survival. Cox regression and survival analyses were employed. Seventy-eight percent of patients developed neuropathic pain that oscillated between a complete absence and presence on a cycle-by-cycle basis. Consequently, the presence of neuropathy in one cycle did not predict the incidence of neuropathy in subsequent cycles. This implies that neuropathic pain need not be a sufficient criterion to reduce, delay, or cease chemotherapy. In the case of multiple system adverse events during combined drug treatment, the responsible cause for dose reduction was not identified. Cox regression analysis revealed that middle age (61-78years old, P=0.003) and oxaliplatin cumulative dose <850 mg/m(2) (P=0.002) were associated with patient mortality. Completion of chemotherapy (8 cycles) and cumulative dose >850 mg/m(2) of oxaliplatin prolonged the median survival time by 8 and 5 months, respectively. As oxaliplatin-induced neuropathic pain fluctuates across cycles in a manner that varies from patient-to-patient, current assumptions on the predictive nature of the emergence of neuropathy (and its impact on treatment compliance) need to be reconsidered. Detailed patient-by-patient analysis of adverse events should be applied to future studies in order to determine the efficacy of current treatments (and future interventions) and whether neuropathic pain should be retained as a criterion to vary the treatment. Additionally, when two or more system toxicities occurred in cases of combined drug treatment, the causes for drug reduction should be separately recorded.