Is mastectomy done even when the cancer has spread to, say, the bones?

In general terms, the standard of care today is that when metastases are present at the time of diagnosis of the primary, then no definitive surgery is performed on the primary unless there is a need to control a bleeding, ulcerated breast for quality-of-life purposes. In recent years, the question has been raised whether removing the breast in the presence of metastasis might favorably affect survival. There is interest in addressing that through additional research and there is at least one ongoing clinical trial outside the United States looking at that, but it is not considered a standard procedure nor is there definitive evidence that it helps. There are no trials currently in the U.S. But there has been some skepticism in the medical community, so there is no trial ongoing or planned for this issue.