Abstract P6-11-05: Incidence and Treatment of Chemotherapy-Induced Neuropathy in Metastatic Breast Cancer: A Claims Database Analysis
Authors: Choe Y , Kim E , Dacosta Byfield S , Balu S , Teitelbaum A. 
Published: April 2011

Abstract
Background: Peripheral neuropathy is a well-known consequence of many cancer chemotherapy agents, particularly the taxanes, platinum compounds, epothilones, and vinca alkaloids. Chemotherapy-induced neuropathy (CIPN) may develop over the course of several cycles of chemotherapy and is characterized by numbness, pain, tingling, weakness, and increased sensitivity that often begins in the fingers and toes spreads proximally. Our objective was to describe the incidence of CIPN in patients with metastatic breast cancer (MBC), the characteristics of patients with CIPN, and the impact of developing CIPN on treatment.
Methods: A claims-based analysis was conducted using commercial, Medicare Advantage and Medicaid data from a national commercial health insurer covering approximately 14 million lives annually. Patients included in the study were female, at least 18 years old, and diagnosed with MBC (at least 2 claims each for breast cancer and metastatic disease, ICD-9-CM codes 174.xx and 196.xx-198.xx, 199.0x) from 01 January 2005 to 31 December 2008. Patients were required to have at least one claim for chemotherapy or one fill date for an oral chemotherapy agent and continuous enrollment with medical and pharmacy benefits for a minimum of 6 months prior to (baseline period), and six months after (follow-up period), the first observed chemotherapy claim date. Patients with evidence of CIPN (at least 2 claims with a peripheral neuropathy (PN) diagnosis on separate days) or receipt of chemotherapy in the baseline period were excluded from the analysis. Descriptive statistics compared baseline characteristics and treatment of patients with and without CIPN. Results: 1875 patients met full inclusion criteria, with a mean (SD) follow-up period of 592 (340) days. Incident CIPN developed in 213 (11.4%) patients. Patients with and without CIPN did not differ significantly in age, insurance coverage type, prior history of surgery or radiation therapy. Patients with CIPN had a longer mean follow-up duration (713 vs. 576 days, P&lt;0.001) which could include chemotherapy rest periods. Gabapentin use was present in 8.9% of patients with and 3.7% patients without CIPN (P&lt;0.001). No significant difference in use of antidepressants or anticonvulsants was noted. Further, more patients with CIPN had neurologist visits (9.9% vs. 5.8%, p=0.023), physical therapy (21.6% vs. 15.4%, p=0.021), and acupuncture (2.4% vs. 0.7%, p=0.012). Among patients treated with chemotherapy agents commonly associated with CIPN, the proportion with PN diagnoses was not significantly different compared to the proportion with CIPN diagnoses among those treated with chemotherapy agents not usually associated with CIPN (11.7% vs 10.1%).
Discussion: Recognition of CIPN may be under-reported in routine clinical practice. In this claims-based analysis, peripheral neuropathy was diagnosed in approximately 11 % of patients with MBC and was associated with more frequent use of neurologist visits, acupuncture, physical therapy, and gabapentin. There was no significant difference in reporting rates between higher and lower risk compounds, which in part may be due to a lack of systematic surveillance.
Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-11-05.