Bored at tumor board.

Why do surgical margins matter? What do they truly mean? Does simply leaving behind a tiny fraction of malignant cells really influence the course of disease, or does the insidious presence of those cells outside visible tumor serve as the harbinger of more aggressive biology? Welcome to back row tumor board musings. A new study in Cell looks at the gene expression profiles of individual cells from head and neck (H&N) primary tumors and nodal metastases and makes some interesting claims about these notorious cells at the margins. Malignant cells that had epithelial-mesenchymal transition (EMT) signatures tended to localize to the leading edge of tumors at the tumor/stroma interface (i.e., the margins). The EMT signature was associated with nodal metastases as well as several other adverse risk factors. So, at least in H&N cancer, this means both margin camps are correct. Tumors with positive margins may have an inherently worse biology, which is exhibited most by those few cells that made it to the margin to be left behind to generate bad clinical outcomes. When it comes to the margin mystery… “Oh, what’s that? Is radiation warranted for this patient?...well, it depends...sorry, what was the primary site again?"