LUMPECTOMY as effective as MASTECTOMY for Early Breast Cancer according to JAMA Oncology.

It's been a source of debate with cancer surgery: some doctors want to remove 2 millimeters or more of normal tissue beyond the edge of the cancer mass. Other doctors believed that 1 millimeter of healthy tissue was fine. Still others thought that a clear margin could be even smaller than 1 millimeter.
They came to a stunning conclusion: A minimal negative margin was just as good as a bigger tissue margin at reducing the risk of cancer coming back in that breast.

Surgeons seem to have adopted the new guideline quickly, resulting in that 16 percent decline in second surgeries in women having lumpectomy for Stage 1 and Stage 2 breast cancer from 2013 to 2015.

"That's a rapid and impressive change in a short period of time," says Morrow, and a "positive step" in the effort to help women choose the best breast surgery options for them. She co-chaired the panel that wrote the guidelines and headed the study.
She thinks in the next few years the number of women having mastectomies could decrease even more.
Numerous studies have found similar survival rates for lumpectomy and mastectomy in people with cancer in one site and a tumor under 4 centimeters.