Apparently real life is not like Trauma Center and tumors don’t come with fun perforated lines showing you where to cut.
Real cancer looks almost identical to the tissue that spawned it, which makes it easy to cut too much or too little. Luckily, science is on it. Here is a TED talk by Tal Danino about releasing bacteria that can only live in tumors, and fluoresce when they reach a certain density:
This is meant as a diagnostic tool. But once you know cancer is there, separating it from the tissue is still an issue. For that I direct you to Quyen Nguyen’s work with florescent stains. Her lab produces a variety of stains in different colors which stain different tissues (she demos on cancer and nerves) to show surgeons what to and not to cut