See also...
http://www.medicalnewstoday.com/articles/272579.php
Interesting.
For many years, it has been possible to inject lab animals with dyes that bind to cancers and fluoresce in imagers, but the use of such dyes in humans is limited for a number of reasons. For one thing, a human being is too big to be imaged the way a rodent can, since most light does not penetrate very far into flesh. These goggles are only looking at surface features, and apparently the dye is only applied to the removed tissue.
This will help remove the entire tumor. It won’t help to find tumor cells that have already migrated somewhere else.