Stynes underwent the risky operation this morning, with the Herald Sun reporting surgeon Jeffrey Rosenfeld was "ecstatic with the outcome".
Stynes' Facebook page reported that "all in all, [the surgery] looks like a big success" with "a big removal/clearance rate on the tumour without any damage".
"I don't know the exact number of operations I have carried out on him now, I have lost count,'' Professor Rosenfeld told the Herald Sun.
"Jim is an amazing stayer who just bounces back and a lot of people just don't bounce back like he does.
"He hasn't been firing on is not firing on all cylinders at the moment but he was certainly keen to get it done.
"The operation went well. Everything as planned, there were no surprises."
Only a fortnight ago, Stynes was told by his oncologist that there was nothing more that could be done with the Brownlow medallist even planning a farewell barbeque before receiving good news from the surgeon that another operation was a possibility.
