Study Design: A retrospective review of case notes and histology reports.

Summary of Background Data: Up to 8% of cancer patients develop second malignancies. The vertebral column is frequently involved in metastatic disease and may represent the first manifestation of malignancy in up to 40% of patients. The rate of vertebral metastasis from a second tumour in patients with a known primary is not well known.

Objective: We sought to identify the incidence of a second primary in patients referred to our unit with spinal malignancy and a previously diagnosed primary tumour.

Subjects: 222 patients underwent definitive surgery for spinal metastatic disease of whom 135 had a prior history of malignancy.

Outcome measures: Histological tissue of origin of spinal metastasis in light of previous known malignancy.

Results: In 16 patients (11.9%) the vertebral histology differed from the initial primary. The period between first and second malignancies varied widely (19 months – 22 years). Thirteen patients (9.6%) had identifiable tissue origins for the metastasis that was not in keeping with the previous malignancy. Three further patients showed sufficient histological and imunohistochemical differences such that a further tumour of unknown origin and not de-differentiation of the previous tumour was suspected. Three previously unrecognised tumours were diagnosed on biopsy and eight on tissue obtained at definitive surgery.

Conclusion: The incidence of second primaries, in particular myeloma, presenting with vertebral metastases is significant and should always be borne in mind when assessing patients and planning treatment. Biopsy should be performed when possible. Comparison needs to be made between the histological features of the previous primary and metastasis.