A lumpectomy is a breast-conserving therapy in which there is surgical removal of a breast tumor with confirmed tumor-free margins.

Delay in effective treatment of breast cancer is an important factor in determining the outcome. When cancer is suspected, or already has been confirmed by open tissue sampling (biopsy) or by needle biopsy, and when the cancer is believed to be small and limited to the breast, it may be possible to treat it by performing a lumpectomy.

In a lumpectomy, only the...