Oncological Causes of Low Back Pain
*Red Flags of LBP that could indicate a more serious condition (click)
Acute low back pain (LBP) is one of the most common conditions for which patients seek treatment. While it is rare for cancer to be the underlying reason for a patient’s LBP (less than 1% of cases), it is important to always consider it a possibility because the lumbar spine is one of the most common sites of metastasis. LBP is common in cancers such as those relating to the lung, prostate, thyroid, breast, and kidney, and when a spine metastasis is confirmed, back pain has been experienced in 90% of those patients.
It is critical to consider cancer as a possible cause of LBP, especially since it may initially present as a mechanical dysfunction. For instance, cancerous back pain or a spinal mass may cause weakness in the legs, and may also cause neurologic signs or symptoms by directly compressing the spinal cord or nerve roots, which imitates disk herniation or stenosis.
Although cancer may mimic a mechanical dysfunction, cancer can usually be recognized or excluded by taking a careful history. It is the most valuable evidence available and is key to differentiating mechanical acute low back pain from more serious etiologies. When taking the history, first clarify the location of the pain, and then systematically establish the features of that pain including onset, duration, intensity, alleviating/exacerbating factors, associated symptoms, and red flags. Patients will present with a diversity of clinical features with symptoms ranging from mild to severe. The following are common signs and symptoms of cancer when a patient presents with acute low back pain.
It is critical to consider cancer as a possible cause of LBP, especially since it may initially present as a mechanical dysfunction. For instance, cancerous back pain or a spinal mass may cause weakness in the legs, and may also cause neurologic signs or symptoms by directly compressing the spinal cord or nerve roots, which imitates disk herniation or stenosis.
Although cancer may mimic a mechanical dysfunction, cancer can usually be recognized or excluded by taking a careful history. It is the most valuable evidence available and is key to differentiating mechanical acute low back pain from more serious etiologies. When taking the history, first clarify the location of the pain, and then systematically establish the features of that pain including onset, duration, intensity, alleviating/exacerbating factors, associated symptoms, and red flags. Patients will present with a diversity of clinical features with symptoms ranging from mild to severe. The following are common signs and symptoms of cancer when a patient presents with acute low back pain.
Signs
o Local/spinal tenderness may be associated with:
o Laboratory or radiology findings:
- belt-like thoracic pain
- radicular symptoms of pain
- weakness in the legs
o Laboratory or radiology findings:
- ESR high
- anemia
- prostate specific antigen or alkaline phosphatase may be elevated
- CT localizes lesions
- MRI demonstrates soft tissue tumor
- X-ray shows bony erosion
- Fracture (may be the first, yet a late stage presentation of a tumor)
Symptoms
o Dull ache, throbbing pain
o Progressive pain
o Pain worse with bed rest
o Hemophtysis (coughing up of blood)
o reduced urine stream
o Increasing frequency and urgency to urinate
o Unexplained weight loss
o Fatigue
o Fever
o Sweats
o Changes in bowel habits
o Hemoptysis
o Lymphadenopathy
o Subcutaneous mass
o Breast mass
o Nipple discharge
o Atypical vaginal bleeding
o Blood in the stool
o Progressive pain
o Pain worse with bed rest
o Hemophtysis (coughing up of blood)
o reduced urine stream
o Increasing frequency and urgency to urinate
o Unexplained weight loss
o Fatigue
o Fever
o Sweats
o Changes in bowel habits
o Hemoptysis
o Lymphadenopathy
o Subcutaneous mass
o Breast mass
o Nipple discharge
o Atypical vaginal bleeding
o Blood in the stool
A more thorough evaluation is required in select patients with “red flags” associated with an increase risk of cancer, or other serious underlying conditions. These patients also require a closer follow-up.
Red Flags of Acute Low Back Pain related to Cancer
o Age ≥ 50*
o Failure to improve after 1 month of therapy*
o Previous history of cancer *
o Unexplained weight loss* (more than 4.5kg in 6 months)
o No relief with bed rest or recumbency
o Pain worse at night
o Insidious onset
o Systemically unwell
o Constant, progressive, nonmechanical pain
o Sensory level (altered sensation from trunk down)
o Anemia
o Fever
o Thoracic pain
o Elevated erythrocyte sedimentation rate(ESR), C-reactive protein level (CRP)
* The four most important clinical findings with the highest positive likelihood ratios for detecting the presence of cancer resulting in LBP. Absence of all four of these clinical findings confidently rules out malignancy.
o Failure to improve after 1 month of therapy*
o Previous history of cancer *
o Unexplained weight loss* (more than 4.5kg in 6 months)
o No relief with bed rest or recumbency
o Pain worse at night
o Insidious onset
o Systemically unwell
o Constant, progressive, nonmechanical pain
o Sensory level (altered sensation from trunk down)
o Anemia
o Fever
o Thoracic pain
o Elevated erythrocyte sedimentation rate(ESR), C-reactive protein level (CRP)
* The four most important clinical findings with the highest positive likelihood ratios for detecting the presence of cancer resulting in LBP. Absence of all four of these clinical findings confidently rules out malignancy.
The majority of patients without a serious pathology usually have more than one positive red flag, and some have very high false positive rates. Therefore, it is not necessary to label a patient with a serious condition like cancer when they only present with one of the many signs or symptoms. Instead, be caution and aware. A thorough follow-up should always be completed on their subsequent visit.
Serious conditions such as cancer are not managed in a primary care setting, and therefore, a required referral for further assessment and specific treatment is crucial. In patients with nonspecific mechanical low back pain, imaging can be delayed for at least 4-6 weeks, which usually is enough time to allow for musculoskeletal conditions to improve with conservative treatment. Based on observational trials, episodes of acute back pain will usually resolve in 6 weeks, regardless of treatment. However, if patient has not made any improvements by week 4 of treatment, reassessment of red flags is indicated. The natural history of back pain is favorable overall, with 60-90% of patients recovering in six weeks, and 95% recovering in 12 weeks. Relapses and recurrences occur in approximately 40% of patients within six months, but with good management, recurrence rates are less than 25%.
Risk Factors
o Advanced Age
o Previous history of cancer
o Hormonal influences (prostate cancer)
o Environmental factors including:
o Gender
o Heredity
o Diet
o Previous history of cancer
o Hormonal influences (prostate cancer)
o Environmental factors including:
- high dietary fat
- high red meat content
- low sun exposure
- decreased vitamin D
o Gender
o Heredity
o Diet
