What workup and imaging studies are recommended for a patient with a history of breast cancer, currently on Tetrahydrocannabinol (THC) regimen, presenting with generalized weakness and a history of falls?

Workup for a Breast Cancer Patient with Recent Falls Due to Generalized Weakness

Initial Assessment and Recommended Workup

For a breast cancer patient on THC with recent falls due to generalized weakness but without head trauma, dizziness, or loss of consciousness, a focused workup should include basic laboratory tests, functional assessment, and targeted imaging only if specific neurological symptoms develop.

Laboratory Evaluation

• Complete blood count (CBC) to evaluate for anemia associated with bone marrow infiltration 1
• Comprehensive metabolic panel including:
  • Liver and renal function tests
  • Calcium levels (to detect hypercalcemia)
  • Alkaline phosphatase (marker of bone formation/turnover) 2
• Vitamin D levels (deficiency common in breast cancer patients and associated with weakness) 1

Functional Assessment

• Detailed musculoskeletal evaluation focusing on:
  • Upper and lower extremity strength
  • Balance assessment
  • Gait evaluation
  • Assessment for musculoskeletal pain that may contribute to weakness 1

Imaging Recommendations

• No routine imaging is indicated in this asymptomatic patient who denies head trauma and is feeling better 1
• Imaging should only be performed if specific symptoms develop or abnormal laboratory values are detected 1, 2
• Avoid unnecessary imaging studies as they provide no benefit in survival or health-related quality of life in asymptomatic patients 1

Rationale and Evidence-Based Approach

Why Extensive Imaging Is Not Recommended

1. According to the American College of Radiology guidelines, routine imaging to detect metastases in asymptomatic breast cancer patients provides no survival benefit 1
2. False-positive findings from unnecessary imaging can lead to expensive diagnostic workups and patient anxiety 1
3. ESMO guidelines state that asymptomatic distant metastases are rare in early breast cancer patients, and most do not benefit from comprehensive radiological staging 1

Special Considerations for THC Use

• THC is commonly used for palliative effects in cancer patients, particularly for symptom management 3
• THC can cause generalized weakness as a side effect, which may explain the patient's symptoms 4, 3
• Consider temporary reduction or adjustment of THC dosage to assess if weakness improves

When to Consider Additional Imaging

Additional imaging should be considered only if:

• New neurological symptoms develop
• Laboratory abnormalities suggest metastatic disease
• Symptoms worsen or do not improve with supportive care 1

Management Recommendations

1. Refer for physical therapy to improve strength, balance, and reduce fall risk 1
2. Consider calcium (1200 mg/day) and vitamin D3 (600-1000 IU/day) supplementation 1
3. Evaluate THC regimen - consider dose adjustment or alternative formulation if weakness persists
4. Implement fall prevention strategies:
   • Home safety evaluation
   • Assistive devices if needed
   • Proper footwear
   • Removal of environmental hazards

Follow-up Plan

• Reassess in 2-4 weeks to evaluate improvement in symptoms
• If weakness persists or worsens despite interventions, consider:
  • Neurology consultation
  • More extensive workup including targeted imaging based on symptoms

Common Pitfalls to Avoid

• Ordering extensive imaging without specific indications in asymptomatic patients
• Attributing symptoms solely to cancer progression without considering medication side effects
• Overlooking the importance of functional assessment and rehabilitation
• Failing to address modifiable risk factors for falls

By following this evidence-based approach, you can provide appropriate care while avoiding unnecessary testing that does not improve outcomes for this patient who is already feeling better after her falls.