A36: Vertebral bone biopsy: establishing diagnosis in cancer of unknown primary

Sarah Scobie1,Sally Clive1

1Edinburgh Cancer Centre, Edinburgh, UK

Presenting date: Monday 2 November
Presenting time: 13.10-14.00

Background

Establishing pathological diagnosis in a timely manner is vital in patients with advanced malignancy.

Bone biopsy of suspicious lesions may be the most technically accessible site but histological diagnosis takes longer than from visceral sites because of decalcification.

Method

A retrospective analysis of 116 consecutive vertebral bone biopsies performed from Jan 2008 to June 2014 inclusive; the mean age was 61 (22-87). 60 were male, 56 female.

Patient demographics, biopsy method, lesion location, radiological appearance and suggested radiological diagnoses collated.

Initial biopsy classified as diagnostic or indeterminate. Pathological subgroup and likely primary site recorded. Timescales assessed efficiency of our service.

Results

Lesion location did not affect biopsy success rate. Most had CT-guided biopsies (85%), 11% were fluoroscopic guided and 4% open biopsy.

Malignancy was diagnosed in 78 patients (67%), infection in 25% and 8% non-diagnostic. None of those with radiologically suspected infection were subsequently found to have malignancy.

90% of patients biopsied because of suspected cancer had diagnostic first biopsies.

17% of lytic lesions were non-diagnostic. Only 2 non-diagnostic biopsies were associated with a crush fracture.

In the 30 patients with a cancer history, 27(90%) had diagnostic vertebral biopsies. In 18(67%), biopsy was consistent with previously diagnosed malignancy, 4(15%) diagnosed a new primary and 2(7%) concluded metastatic cancer of unknown primary (mCUP); the remaining 3 were benign.

It took a median of 9.6 days from biopsy to result.

Death from date of malignant biopsy ranged from 2 days to 43 months (median 10 weeks). 73% died within 6 months of biopsy, 22% of whom died within 6 weeks.

31 out of 34 biopsies (91%) performed in mCUP were diagnostic. 77% provided immunohistochemistry that helped indicate a likely primary site. 7 remained mCUP,  mostly poorly differentiated carcinoma.

Conclusion

Vertebral biopsy provides enough tissue to indicate likely primary cancer site in most.

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