Which chemotherapy agent is commonly associated with foot drop and peripheral neuropathies?

• A. Cisplatin
• B. Methotrexate
• C. Vincristine
• D. Doxorubicin

Answer: (C)

Chemotherapy-induced peripheral neuropathy is a common adverse effect of several cancer drugs, but one agent stands out for causing notable motor weakness that can manifest as foot drop. Vincristine disrupts microtubule polymerization by binding tubulin, which blocks mitosis in cancer cells but also impairs axonal transport in neurons. This leads to distal, predominantly symmetric peripheral neuropathy with both sensory and motor involvement. The motor component can weaken the dorsiflexors of the foot, producing foot drop, which is a classic clinical sign of vincristine-related neurotoxicity. Other agents may cause neuropathy, but their patterns are less characteristic of foot drop, whereas vincristine is especially known for this neurotoxic effect.