The levels of iron (Fe), copper (Cu), zinc (Zn) and potassium (K) have been measured in normal and malignant liver and kidney tissue using X-ray fluorescence. Zn was reduced in liver and kidney tumours by 63% and 26%, respectively. Fe, Cu and K were increased in kidney tumours by 150%, 8% and 90%, and reduced in liver tumours by 76%, 29% and 43%. A synchrotron microprobe was used to map calcium (Ca), Fe, Cu and Zn in breast tissue. The distributions were compared to reference images and higher concentrations of metals correlated with areas of cancer cells. The average increase of Ca, Fe, Cu and Zn concentrations in areas of malignancy were 70%, 43%, 53% and 87%.