Determine the prevalence, severity and risk factors for chemotherapy induced peripheral neuropathy (CIPN) at 0 and 2 years after the completion of paclitaxel therapy for breast cancer.

CIPN is a dose limiting side effect of neurotoxic chemotherapy which carries substantial morbidity. CIPN risk factors and natural history are poorly understood.

Retrospective chart review of breast cancer patients treated with paclitaxel monotherapy at the University of Utah between 1999 and 2015. Medical records were reviewed to determine diagnosis of CIPN and assign NCI CTCAE severity (if not documented). Risk factors analysis evaluated by ICD9/10 codes of medical problems prior to chemotherapy.

N=565, mean age 51.9(±12.25). 99.97% female, 57.7% weekly and 42.3% dose dense paclitaxel.  Mean total paclitaxel dose (mg/m2) of those with vs. those without CIPN was 753.7±231 vs. 731.5±.256.0 p=0.343. Only 11.8% of those with documented CIPN had a documented CTCAE neuropathy severity score.

At the conclusion of chemotherapy: 73% had CIPN: 32% grade 1, 36% grade 2, 4% grade 3, <1% grade 4 neuropathy.  At 2 years after chemotherapy: 36% had CIPN: 20% grade 1, 15% grade 2, >1% grade 3. 

Risk Factor Analysis: Relative risk and confidence interval at completion  and 2 years:  

type 2 diabetes 1.120(.976-1.285) and 1.323(1.056-1.658), idiopathic polyneuropathy 1.350(1.290-1.420) and 2.050(1.88-2.235), alcoholism 0.669(.0334-1.240) and 1.528 (1.015-2.301), hyperlipidemia 1.101(.966-1.256) and 1.349(1.097-1.658), chronic hep C 1.009 (.966-1.256) and 2.038(1.187-2.220), hypocalcemia 1.345(1.283-1.417) and 1.001(.338-2.704), previous neuropathy related to a drug 1.346(1.281-1.412) and 2.026(1.860-2.206), essential hypertension 1.098(.987-1.22) and 1.369(1.153-1.1622).

The prevalence of CIPN after paclitaxel therapy approaches 75% and over 1/3 of patients continue to have CIPN after 2 years. .Amongst other risk factors, the components of metabolic syndrome are associated with increased risk of persistent CIPN. More detailed prospective study is needed to better understand CIPN risk factors.