Is there some way of detecting cancers using sound waves?

Chris - Definitely. This was experimental but very exciting. One of the big problems with cancer spreading around the body or cancers that may be so tiny or almost impossible to see on the skin surface, for example, is how do you know if they're already in the blood stream? Cancers throw off cells. These are called metastaces or metastatic cells. If you've got malignant melanoma which is making a lot of melanin, a dark pigment what you can do is take blood samples and there might be one in a million cells in the blood stream which is a malignant melanoma. Scientists have found that if you zap this with laser light at a frequency which the melanoma will absorb but other cells won't then the cell can be made to resonate. It makes a sort of snapping or ricocheting-like noise which you can hear with a very sensitive microphone and this tells you the cells are there.