Conservation science.

Top Line: The debate continues on the merits of breast conservation versus mastectomy.

The Study: While it took decades to firmly cement breast conserving surgery, usually with adjuvant radiation, as a safe alternative to mastectomy for the treatment of breast cancer, it’s now mastectomy that’s on the chopping block. That’s right, numerous population-based studies have revealed worse survival outcomes following mastectomy. Here’s yet another one, this time a look at outcomes among a prospectively curated Swedish database of nearly 49,000 women undergoing resection of T1-2N0-2 breast cancer (probably amenable to breast conservation). Once again, when compared to breast conservation with radiation, breast cancer-specific survival was significantly worse after mastectomy with (HR 1.26) or without (HR 1.66) radiation. In other words, a breast-conserving approach was associated, once again, with tremendous relative improvements in breast cancer-specific survival regardless of the addition of post-mastectomy radiation. This held true throughout all nodal burdens, even though higher nodal burden was associated with receiving a mastectomy. There are myriad hypotheses to explain this intriguing finding, and it should all be coupled with data revealing worse quality of life outcomes with mastectomy.

TBL: “This report gives no support to advocate mastectomy [for breast conservation-eligible primary tumors] in women without specific risk factors, such as a strong family history or gene mutations.” | Boniface, JAMA Oncol 2021