Skeletal metastases

Spinal pain due to metastasis of unknown origin

A 58-year-old woman presented with non-radicular pain in the upper thorax. Due to the prolonged duration of symptoms, a bone scintigraphy was made, which showed pathological enhancement in the upper thoracic spine. An MRI demonstrated lesions of the third and fourth thoracic vertebrae. A biopsy showed a metastasis of poorly differentiated carcinoma. A whole-body 18-F-FDG PET scan failed to identify a primary tumour. The patient was given radiotherapy, chemotherapy and analgesic treatment. She died within 3 years. In the late stage, the tumour marker CA 19-9 was positive; however, an MRI of the abdomen failed to identify a pancreatic tumour. Metastasis from an unknown primary site can present as cervical spinal disease very similar to degenerative disease.

Rapid magnetic resonance imaging for diagnosing cancer-related low back pain

OBJECTIVES

This study compared the relative efficiency of lumbar x-ray and rapid magnetic resonance (MR) imaging for diagnosing cancer-related low back pain (LBP) in primary care patients.

DESIGN

We developed a decision model with Markov state transitions to calculate the cost per case detected and cost per quality-adjusted life year (QALY) of rapid MR imaging. Model parameters were estimated from the medical literature. The costs of x-ray and rapid MR were calculated in an activity-based costing study.

SETTING AND PATIENTS

A hypothetical cohort of primary care patients with LBP referred for imaging to exclude cancer as the cause of their pain.

MAIN RESULTS

The rapid MR strategy was more expensive due to higher initial imaging costs and larger numbers of patients requiring conventional MR and biopsy. The overall sensitivity of the rapid MR strategy was higher than that of the x-ray strategy (62% vs 55%). However, because of low pre-imaging prevalence of cancer-related LBP, this generates <1 extra case per 1,000 patients imaged. Therefore, the incremental cost per case detected using rapid MR was high ($213,927). The rapid MR strategy resulted in a small increase in quality-adjusted survival (0.00043 QALYs). The estimated incremental cost per QALY for the rapid MR strategy was $296,176.

CONCLUSIONS

There is currently not enough evidence to support the routine use of rapid MR to detect cancer as a cause of LBP in primary care patients.

Analgesic effects of calcitonin

The analgesic activity of salmon calcitonin (subcutaneous or intranasal) has been demonstrated in several prospective clinical trials, in patients suffering different painful skeletal conditions, including recent nontraumatic osteoporotic vertebral fractures. The mechanism of the analgesic effect of calcitonin is not clear. It is possible that specific binding sites for salmon calcitonin exist in the brain. Another explanation is that changes in descending serotonergic modification on the sensory transmission mediated by C afferents contribute to the analgesic effects of calcitonin on pain in osteoporotic patients. From the clinical point of use, the analgesic effect of calcitonin is beneficial throughout the whole period of medical treatment of osteoporotic patients. Salmon calcitonin in a daily dose of 100 IU subcutaneously or 200 IU intranasally reduces dramatically the back pain (p < 0.0005) after a recent osteoporotic vertebral fracture, and promotes the early mobility of patients. The finding that injectable or intranasally administered salmon calcitonin effectively controls severe pain in osteoporotic patients with a recent vertebral fracture, allowing them earlier mobility in combination with a reduction of the urinary hydroxyproline excretion, and a limitation of the considerable bone loss that may occur during prolonged bed rest, make this therapeutic scheme attractive.