2nd National Multi-Disciplinary Mammotome User Group Conference
Peter Britton, Consultant Radiologist, Cambridge
Forty delegates, mostly Consultant Breast Radiologists, from all over the U.K. met for a 2 day conference to present and discuss the current status of indications and use of mammotome biopsy.
Guidelines
The current NHSBSP Screening Assessment Guidelines (1) were reviewed along with the recent NICE Guidelines (2) on image-guided vacuum assisted excision biopsy of benign breast lesions. These latter guidelines support the use of excision of benign lesions providing users have adequate training (3) and the issues of patient consent, audit and clinical governance are addressed.
Stereotactic-guided Vacuum Assisted Biopsy (VAB)
The conclusions from the presentations and users experiences are that VAB was a useful addition to the breast diagnostic armamentarium. This is especially so for microcalcification where improved calcium yields should be expected with a concomitant rise in pre-operative diagnosis rate. Paradoxically there may not be a reciprocal reduction in the benign surgical biopsy rate because of increasing diagnosis of B4 and, especially, B3 lesions. There was extensive debate regarding the pathological implications of B3 lesions exhibiting atypia diagnosed on VAB and their subsequent management. The consensus view was that B3 lesions exhibiting epithelial atypia should continue to undergo diagnostic surgical excision until harder scientific evidence as to the risk of concomitant malignancy is more rigorously defined.
It is clear that stereotactic VAB is well tolerated by patients and that the complication rate is extremely low. The technique can successfully be taught to advanced practitioners although it was felt that this should probably be after experience is gained in stereotactic core biopsy.
Ultrasound-guided VAB
(a) Diagnostic Uses
On the whole, this is less frequently performed than stereotactic VAB. It is of proven diagnostic help in patients who have previously had a B1, B3 or B4 core biopsy result. It is also useful when there is radiological-pathological discordance e.g. B2 core biopsy from a radiologically suspicious lesion. Its use in determining tumour extent towards the nipple was also described in patients undergoing nipple sparing mastectomy.
(b) Diagnostic and Possible “Therapeutic” Uses
If thorough and extensive sampling [at least 12 passes 11G needle (1)] of a radial scar or papillary lesion is undertaken and there is no evidence of atypia or malignancy then no further surgical intervention may be required. Data was also presented regarding ultrasound VAB used as a diagnostic and therapeutic procedure for patients with nipple discharge in lieu of microdochectomy or sub-areolar duct clearance. Ultrasound VAB is also being successfully used in patients with gynaecomastia although this may also require liposuction in conjunction with plastic surgeons.
(c) Therapeutic
VAB may be used to excise proven benign lesions (e.g. a fibroadenoma) if this is a patient’s wish and would avoid surgical removal.
The use of ultrasound VAB was also described to drain abscesses that are refractory to standard percutaneous drainage.
MR-guided VAB
Preliminary experience on setting up MR guided VAB was presented. It is clear that there is still only patchy provision of MR guided breast biopsy in the UK and that we should work towards the provision of regional centres with expertise in managing the biopsy of lesions only visible with MR.
VAB following Core biopsy
VAB may prove useful in dealing with:
- Lesions that have yielded B1 core biopsy, where satisfactory targeting or adequate sampling is an issue.
- Lesions that have yielded a B2 core biopsy, where the lesion is radiologically suspicious.
- Lesions that have yielded a B3 core biopsy where histological change is minor and there is a reasonable expectation that a VAB may provide a definitive benign diagnosis and thus avoid unnecessary surgical excision. Some B3 lesions on core biopsy may be upgraded to B5 malignancy on subsequent VAB, however experience suggests that this occurs infrequently and the majority of B3 core biopsies with atypia will still require diagnostic surgical excision.
- Lesions that have yielded a B4 core biopsy where there is a high degree of pathological or radiological suspicion of malignancy and hence a reasonable expectation that a VAB will yield a B5 malignant result thus enabling therapeutic surgery.
CONCLUSIONS
VAB is useful and, when available, may be considered the sampling method of choice in the following:
- Biopsy of microcalcification.
- Some lesions that have yielded B1, B2, B3, or B4 core biopsy results (see VAB following CB section above).
- Diagnostic excision of radial scars and papillary lesions without evidence of epithelial cytological atypia on core biopsy.
Excision of known benign lesions through patient choice.
Further potential developments:
- Ultrasound-guided VAB in the management of nipple discharge, gynaecomastia and breast abscess.
- Further audit and research should be undertaken to evaluate the pathological significance and subsequent management of VAB’s that reveal B3 pathology with atypia.
- The provision of MR-guided biopsy should become more widely available with the development of regional tertiary referral centres.
Acknowledgements:
Thanks to Drs Barbara Dall, Hilary Dobson, Chris Flowers, Joyce Liston, Sarah Pinder and Ruchi Sinnatamby for their helpful comments.
References:
- Clinical Guidelines for Breast Cancer Screening Assessment NHSBSP Publication No 49
Jan 2005 Second Edition - Image-guided vacuum-assisted excision biopsy of benign breast lesions. NICE guidelines February 2006
- Ultrasound Training Recommendations for Medical and Surgical Specialties. The Royal College of Radiologists, January 2005