It seems surprising that the laser has such selective activity on CTCs versus healthy cells. Why are these cells so much more absorbtive? Is this specific to melanoma CTCs (more pigment)?

I also wonder how they did this measurement. Seems like you'd need to take pre- and post-laser measurements of healthy and CTC counts in the bloodstream to have high confidence that it is disproportionately damaging CTCs. To what extent does this damage healthy cells?