The distribution of trace elements Ca, Fe, Cu and Zn and the determination of copper oxidation state in breast tumour tissue using μSRXRF and μXANES

A micro beam synchrotron x-ray fluorescence (mu SRXRF) technique has been used to determine the localization of metals in primary invasive ductal carcinoma of breast. Nine samples were examined, all of which were formalin fixed tissues arranged as micro arrays of 1.0 mm diameter and 10 mu m thickness. Cu was the particular interest in this study although 2D maps of the elements Ca, Fe and Zn, which are also of physiological importance, are presented. The distribution of these metals was obtained at approximately 18 mu spatial resolution and compared with light transmission images of adjacent sections that were H and E stained to reveal the location of the cancer cell clusters. Correlations were found between these reference images and the elemental distributions indicating an increase in all element concentrations in the tumour regions of all samples, with the exception of Fe, which in some cases showed a reverse of this trend. On average over all samples the percentage difference from the normal tissue elemental concentrations are Ca approximate to 67%, Cu approximate to 64% and Zn approximate to 145%. Micro x-ray absorption near edge spectroscopy (mu XANES) was used to estimate the oxidation state of Cu in 19 normal and 17 tumour regions spread over five samples. The shape and the position of both normal and tumour regions suggest that they contain mixtures of copper ions with a significant fraction of Cu(2+). However, the shape of the spectra does not exclude the presence of Cu(+). Tumour regions were found to have a higher fraction of Cu(+) compared to the normal samples.