What is the best next step for a 63-year-old woman with a history of stage three breast cancer, currently experiencing new low back pain radiating down her left leg, taking oxycodone (opioid) and pregabalin (anticonvulsant), with allodynia over the left chest wall and non-tender low back?

Management of New Low Back Pain with Radicular Symptoms in a Cancer Survivor

Imaging of the spine is the best next step for this 63-year-old breast cancer survivor with new low back pain radiating down her left leg, as this presentation raises concern for possible metastatic disease.

Clinical Assessment and Reasoning

This patient presents with several concerning features that warrant immediate imaging:

• History of stage three breast cancer with existing neuropathy
• New onset low back pain with radicular symptoms (pain radiating down left leg)
• Pain worsening with walking
• Current treatment with oxycodone and pregabalin not controlling the new symptoms

Why Imaging is Necessary

Breast cancer commonly metastasizes to bone, and the new onset of low back pain with radicular symptoms in a cancer survivor must be evaluated for possible spinal metastases before other interventions are initiated 1. The National Comprehensive Cancer Network (NCCN) guidelines recommend screening for cancer pain at regular intervals in survivors, with appropriate evaluation of new pain symptoms 1.

Type of Imaging Recommended

• MRI of the lumbar spine is preferred as it can detect:
  • Metastatic disease
  • Disc herniation causing nerve compression
  • Spinal stenosis
  • Vertebral compression fractures

Why Other Options Are Not Appropriate First Steps

Addition of Ibuprofen

While NSAIDs are recommended for back pain 1, 2, adding ibuprofen without imaging is inappropriate in this case because:

• It may mask symptoms of underlying serious pathology
• The patient already has an established pain regimen with oxycodone
• NSAIDs should be used with caution in cancer patients due to potential interactions with chemotherapy and risk of renal, GI, and cardiac toxicities 1

Physical Therapy

Physical therapy is beneficial for many types of back pain 2, but is not the appropriate first step because:

• Underlying pathology must be ruled out before initiating physical therapy
• If metastatic disease is present, certain physical therapy interventions could potentially cause harm
• NCCN guidelines recommend appropriate diagnosis before referral to physical therapy for cancer survivors 1

Addition of Extended-Release Opioid

Increasing opioid therapy without determining the cause of pain is not appropriate because:

• The patient is already taking oxycodone
• Escalating opioid therapy without understanding the underlying cause could mask important symptoms
• NCCN guidelines recommend using the lowest opioid dose possible and reevaluating effectiveness regularly 1
• Opioid efficacy for low back pain with radicular symptoms is inconclusive 1

Follow-Up Management Based on Imaging Results

If Metastatic Disease is Detected:

1. Urgent referral to oncology
2. Consider radiation therapy for localized bone pain 3
3. Consider bisphosphonates 3
4. Pain management may include:
   • Optimization of current opioid regimen
   • Addition of glucocorticoids for inflammatory component
   • Consideration of interventional procedures for refractory pain 1

If Disc Herniation/Radiculopathy is Detected:

1. Consider adding an NSAID if no contraindications exist 2
2. Optimize current pregabalin dosing for neuropathic component 4
3. Physical therapy with focus on active interventions 2
4. Consider referral to pain management if symptoms persist 1

Important Considerations

• Monitor for signs of cauda equina syndrome (urinary retention, saddle anesthesia, bilateral leg weakness), which would require emergency surgical intervention 2
• Reassess pain control regularly using validated pain scales
• Consider the psychosocial impact of pain in cancer survivors
• Avoid bed rest and encourage appropriate activity as tolerated once serious pathology is ruled out 2

This approach prioritizes ruling out serious pathology while preparing for appropriate targeted treatment based on imaging findings, which is essential for optimizing both mortality and quality of life outcomes in a cancer survivor with new back pain.