Multiple myeloma (MM) is the second most frequent hematological malignancy and comprises about 1% of all cancers, and 10% of hematological malignancies.
Some of the agents used for treatment of MM may lead to peripheral neuropathy (PN) such as, thalidomide, bortezomib, and less commonly lenalidomide and carfilzomib.
PN is usually sensory neuropathy that may be accompanied by motor and autonomic neuropathy.
Vitamin D is known to decrease the possible damage to the peripheral nervous system.
Vitamin D has many essential functions in brain, including maintaining calcium balance and signaling, neurotrophic factors regulation, neuroprotection, neurotransmission modulation, and contributing to synaptic plasticity.
Vitamin D has important role in neuronal differentiation, maturation, through alterations in several neurotrophic factors, with increased synthesis of nerve growth factor (NGF), glial cell line–derived neurotrophic factor (GDNF), and neurotrophin 3 (NT-3), and with decreased synthesis of NT-4.
Serum levels of vitamin D have been inversely linked with painful symptoms and increased sensitivity to pain.