Source: DGNews  |  Posted 3 years ago

By Kristina Rebelo

SAN DIEGO -- April 16, 2008 -- Evidence has been found of metastatic dissemination after core needle biopsy in an in vivo model of human tumour metastasis, researchers reported in a poster presented here at the Annual Meeting of the American Association for Cancer Research (AACR 2008).

In 2005, the American College of Surgeons Consensus Conference issued an official statement regarding the diagnostic workup of image-detected breast abnormalities, saying that breast cancer treatment should optimised by making a definitive diagnosis prior to entering the operating room. Guidelines include the use of image-guided percutaneous needle biopsy as the gold standard for diagnosing image-detected breast abnormalities.

Several studies have demonstrated tumour cell displacement along needle tracks and into draining lymph nodes following core needle biopsies, but the clinical consequences are a subject of ongoing debate.

Lead study author Carmen Giacomantonio, MD, Associate Professor, Department of Surgery, Dalhousie University, and Chief of Breast and Adult Surgery, IWK Health Centre, Halifax, Nova Scotia, explained: "The reality is that the core biopsy probably does result in significant clinical metastases in a small percentage of patients. The problem is that it's impossible to know -- it's not detectable statistically in clinical studies because the endpoints are crude."

To test their hypothesis, Dr. Giacomantonio and colleagues used MDA-MB435 cells grown on the chorioallantoic membrane (CAM) of 8-day-old chick embryos.

The results, presented on April 13, demonstrated that core needle biopsy significantly increased overall metastatic burden in a number of distant organs, such as the liver, lung, and brain. Additionally, evidence was seen for a biopsy-induced trophic shift in the pattern of metastatic dissemination observed in the biopsied chick embryos when compared with the pattern of metastases observed in the nonbiopsied tumours.

"In our study, we actually demonstrated that tumours have a natural propensity to metastasise and in some of the cell lines that we tested, the biopsy had no influence over the natural metastasis rate," said Dr. Giacomantonio in a telephone interview. "But in cell lines that had a highly significant metastatic potential, the biopsy had more of a significance on them. So in essence, what we're looking at is a small percentage of tumours that already have a highly metastatic potential, and we are influencing this potential by the core biopsy and the biological response to core biopsy, which is essentially a healing response."

Results yielded a proportionately larger increase in lung metastases relative to CAM metastases, suggesting a trophic alteration in the metastatic behaviour of the cancer cells in the core needle-biopsied group.

Experimental results support clinical reports of tumour cell displacement into lymph nodes following core needle biopsies. Additionally, the study pointed out that the change in pattern of increase in metastasis observed in biopsied animals is related, at least in part, to a biological alteration (trophic change) in the breast cancer cells and/or tumour microenvironment resulting from the core needle biopsy, rather than being entirely a consequence of mechanical displacement of cells into the surrounding vasculature.

"Essentially, we recognise that the lymph nodes have small metastases and that these metastases are a consequence of core biopsy but have not been demonstrated to be of clinical significance," said Dr. Giacomantonio. "The work is well underway and will be submitted for publication in the next couple of weeks. This is data that needs to be studied carefully in a more appropriate model.

Presenter and co-author John Lewis, PhD, Assistant Professor, Department of Oncology, Director, Translational Prostate Cancer Research Group, University of Western Ontario, London, Ontario, said, "This is not to strike a fear in anyone but is a caveat. Next, we need to know what is causing the migration and the next step is to find out the mechanism. Is the needle itself displacing the cells into the vasculature?"

Dr. Lewis said that they will look at using a localised therapeutic, such as docetaxel, applied to the region to prevent cells from migrating. Plans are also in the works to do a microarray analysis to see if any genes are being turned on by the core biopsy procedure in areas of angiogenesis, inflammation, and migration.

[Presentation title: Evidence for Increased Metastatic Dissemination after Core Needle Biopsy of Breast Cancer in an in vivo Model of Human Tumour Metastasis. Poster 16, LB-95]