1. Background
Chemotherapy-induces peripheral neuropathy (CIPN) is a common complication of chemotherapy agents with a significant impact on patients’ quality of life. The risk of developing CIPN is higher among conventional chemotherapy drugs especially with platinum (e.g., cisplatin and oxaliplatin), taxanes, and vinca alkaloids [1, 2].
The development of CIPN during antineoplastic therapy is one of the most common cause of the termination or modification of cancer treatment [3]. Peripheral neuropathy may present as sensory, motor, or autonomic dysfunction. Clinical signs of neurological complications include paresthesia, numbness of the fingers, gait disturbance, ataxia, loss of deep tendon reflexes, wrist or foot drop, facial nerve palsy, and optic neuropathy [4, 5].
The functional impairment of neurons induced by chemotherapeutic drugs may be mediated through oxidative stress, inflammation, apoptosis and electrophysiological disturbances [6]. In oxidative stress, the release of oxygen free radicals including hydrogen peroxide, superoxide ions, and nitric oxide causes changes in cell components which may lead to lipid peroxidation and subsequent cell death [7-9]. Silymarin is a flavonoid mixture extracted from Silybum marianum seed, which consists of a mixture of flavolignans including silibinin, isosilibinin, silicristin, and silidianin [10]. Although silymarin has been mostly known as its hepatoprotective properties [11], growing evidence has shown the neuroprotective effects of silymarin in neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and cerebral ischemia, via reducing reactive oxygen species (ROS), decreasing inflammatory cytokines, and altering cellular apoptosis pathway [12]. Beside the positive effect on CIPN, Laboratory data show that silymarin and its compounds (especially silibinin) have strong anticarcinogenic effect against cancer cells such as breast cancer and human promyelocytic leukemia HL-60 cells [13, 14].
It is acknowledged that the treatment of peripheral neuropathy is difficult and completely relieve of peripheral neuropathy (especially associated pain) may not occur with current therapies and complementary therapies may help in better management of CIPN [4, 15, 16].
The aim of this study was to evaluate the efficacy and side effects of silymarin in the treatment of peripheral neuropathy caused by chemotherapy drugs.