Scientists are looking to the elements to detect cancer cells before they spread.

Philip Doble from the University of Technology in Sydney and colleagues in Australia and the US have used a mass spectroscopy imaging technique to map skin cancer cells in human tissue. The method measures phosphorus concentrations as a diagnostic tool for metastatic melanoma.

Melanomas are malignant tumours which it has been estimated took in excess of 65000 lives in 2000. The tumours are found predominately in skin but spread - metastasise - through the lymphatic system, making mapping this spread imperative. Nodes in the lymphatic system can act as filters to trap foreign particles and so often trap cancerous cells on the move. Approximately 20 per cent of melanoma patients have these cells in their lymph nodes, so it is a good place for scientists to look for early diagnosis. 

Imaging phosphorus concentration provides a clear outline of a melanoma tumour in a lymph node

Doble uses a mass spectroscopy technique called elemental bio-imaging to measure the trace element concentrations in cells. As altered levels of trace elements, such as phosphorus and sulfur, have long been associated with malignancy, the technique allows Doble and his team to identify cancerous cells by constructing maps of single (or ratios of) elements. In this way, they were able to provide clear images of a melanoma tumour in a lymph node and its boundary with the neighbouring healthy tissue. 

The severity of melanoma is usually identified by using a surgical procedure to carry out lymph node biopsies to determine how far the cancer has spread, then staining and examining the cells under a microscope. If cancer cells are found, the patient will have all the surrounding lymph nodes surgically removed to prevent the cancer spreading. Doble's method uses a much less invasive procedure, which extracts the lymph node biopsy samples with a needle.

Joanna Peak, science information officer at Cancer Research UK, says 'this study highlights the potential for developing new imaging methods that could improve detection of cancer spread. If these findings are developed further and evaluated more fully in the clinic they could lead to a less invasive and more efficient method for identifying melanomas that have spread by the time of diagnosis.'

Whilst in this case the team monitored phosphorus, sulfur and zinc levels and ratios, Doble suggests that the method also has the potential to image and analyse diseases in which other elements are known to play a role. 'Trace elements such as copper, zinc and iron are implicated in the progression of many neurological disorders such as Parkinson's and Alzheimer's disease,' he says. 

Emma Shiells

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