Technetium-99m sestamibi: an indicator of breast cancer invasiveness

As recently shown, angiogenesis is the most reliable marker of breast cancer invasiveness. Unfortunately it must be assessed by immunohistochemistry on tissue specimens. We have used technetium-99m sestamibi, a marker of regional blood flow in other organs that often but not always images breast cancer, to assess the invasiveness of this tumour. Nineteen patients, ten with nodal metastases and nine without any metastases, were studied with ^99mTc-sestamibi scintigraphy before operation. Angiogenesis was quantitatively assessed by immunohistochemical staining of endothelia for factor VIII. All the node-positive (N+) patients at surgical revision showed a positive ^99mTc-sestamibi scan of the primary tumour and all the N-patients were negative. Nine out of ten N+ and sestamibi-positive tumours showed more than 135 microvessels/mm² and one showed 99 microvessels/mm²; by contrast there were 71.6±12.1 microvessels/mm² in the nine N- and sestamibi-negative tumours. Our study suggests that ^99mTc-sestamibi is a marker of breast cancer invasiveness: its uptake is related to angiogenesis and, possibly, to oxidative metabolism of the tumour.