As always with such a question, define “best”.
There are many different cancers, a surgeon who is best for total mastectomies, may be a poor choice for conservative surgery which preserves as much of the breast as possible.
Also do you mean worldwide best, or just best in your country.
“Best” can also refer to lowest mortality rates during surgery or perhaps longest survival rates after surgery. It might mean “best” for tackling the most difficult cases, or “best” as in lowest professional fees.
Or perhaps you meant “best” in terms of research and peer-reviewed publications?
In short, there is no single, all-encompassing “best”. And even if there was, it might be pointless to recommend one who is about to retire and who already has a full waiting list or one who is based solely in South Korea if you live in Detroit USA and cannot afford the cost of a top surgeon in an alien nation.
Your own family doctor should be able to make evidence-based suggestions.