Kidney cancer. Heavy metals as a risk factor

The association between exposure to heavy metals and cancer has been extensively studied, although the mechanisms involved are far from being completely understood. Concerning renal cell carcinoma, several heavy metals have been implicated as risk factors, namely cadmium (Cd) and lead (Pb). Herewith, we investigated the presence and distribution of heavy metals in samples of renal cell carcinoma, as well as adjacent renal tissue (control samples), in patients submitted to radical or partial nephrectomy for renal cell carcinoma. Samples from renal tumour and adjacent renal tissue were processed and observed by Scanning Electron Microscopy coupled with X-Ray Microanalysis (SEM-XRM), in order to detect and quantify heavy metals in situ, using the JEOL JSM-6301F microscope. Our results revealed a significant difference in the composition of heavy metals between the renal adjacent tissue (control) and the tumour tissue. No heavy metal particles were detected in the adjacent (control) tissue, by this technique, but the presence of heavy metals such as chromium (Cr), iron (Fe) and copper (Cu) were detected among other particles which could be seen in the tumour tissue samples. Our results might suggest a possible role of heavy metals in the oncogenic pathway of renal cell carcinoma. However, there is controversy regarding this topic: 1 - Is this anomalous sequestration of heavy metals just an epiphenomenon or is this a hint of a causal mechanism? 2 - Can heavy metals be used as biomarkers with potential diagnostic or prognostic interest? For example, could they be used to improve the diagnostic value of renal biopsy in clinical practice?