What lab investigations are recommended for an elderly female with vaginal cancer stage IIIA experiencing peripheral neuropathy while on cisplatin (platinum-based chemotherapy) therapy?

Laboratory Investigations for Cisplatin-Induced Peripheral Neuropathy

For an elderly female with vaginal cancer stage IIIA experiencing peripheral neuropathy on cisplatin, you must obtain renal function tests (serum creatinine, BUN, creatinine clearance), serum electrolytes (magnesium, sodium, potassium, calcium), complete blood count with differential, and liver function tests prior to each subsequent dose. 1

Mandatory Pre-Treatment Laboratory Monitoring

The FDA label for cisplatin explicitly requires the following laboratory assessments before each subsequent course of therapy:

• Serum creatinine 1
• Blood urea nitrogen (BUN) 1
• Creatinine clearance 1
• Serum magnesium 1
• Serum sodium 1
• Serum potassium 1
• Serum calcium 1

These measurements are critical because cisplatin produces cumulative nephrotoxicity, and elderly patients are more susceptible to both nephrotoxicity and peripheral neuropathy. 1

Hematologic Monitoring

• Peripheral blood counts should be monitored weekly during cisplatin therapy 1
• Complete blood count with differential to assess for myelosuppression, as elderly patients experience more severe neutropenia, thrombocytopenia, and leukopenia compared to younger patients 1

Additional Required Monitoring

• Liver function tests should be monitored periodically throughout cisplatin therapy 1

Clinical Assessment Requirements

While not laboratory tests per se, the FDA mandates:

• Neurologic examination should be performed regularly to assess the progression of peripheral neuropathy 1
• Audiometric testing should be performed prior to each subsequent dose, as cisplatin causes cumulative ototoxicity 1

Critical Pitfalls to Avoid

Do not continue cisplatin at the standard dosing interval if neuropathy is present. Cisplatin should not be given more frequently than once every 3-4 weeks at recommended dosages. 1 Higher doses or greater dose frequencies are associated with severe, potentially irreversible neuropathies manifesting as paresthesias in a stocking-glove distribution, areflexia, and loss of proprioception and vibratory sensation. 1

Elderly patients require heightened vigilance. This population is more susceptible to peripheral neuropathy, nephrotoxicity, myelosuppression, and infectious complications. 1 Since cisplatin is substantially excreted by the kidney and elderly patients are more likely to have decreased renal function, dose selection must be carefully considered based on renal function monitoring. 1

Management Considerations Based on Laboratory Results

If laboratory monitoring reveals:

• Renal impairment: Cisplatin is contraindicated in patients with pre-existing renal impairment 1
• Electrolyte abnormalities: These must be corrected before proceeding with therapy, as cisplatin causes cumulative nephrotoxicity potentiated by electrolyte disturbances 1
• Severe myelosuppression: Dose reduction or treatment delay is warranted 1

Treatment of Established Neuropathy

For the symptomatic management of painful chemotherapy-induced peripheral neuropathy that has already developed, duloxetine is the only agent with adequate evidence supporting its use, starting at 30 mg daily for one week, then increasing to 60 mg daily. 2, 3 However, the benefit is limited. 3

There are no established agents recommended for the prevention of chemotherapy-induced peripheral neuropathy. 3 Specifically, do not use acetyl-L-carnitine, calcium/magnesium, gabapentin, pregabalin, glutathione, or vitamin E for prevention, as these lack efficacy or may cause harm. 2, 3