Ever since the 1970's, when lumptectomy was shown to be as effective as mastectomy for treating early-stage breast cancer, surgeons have been stumped by one of the most vexing problems in oncology: how wide should the margins be around the tumor to insure adequate removal of the cancer so that the risk of local recurrence or, worse, distant metastatic spread can be driven down as low as possible?
Early on, the conventional wisdom was that surgeons needed a 1.0 cm (about a half inch) negative margin surrounding the tumor to achieve the best results. This was the information I was given when I first started practicing as a breast cancer surgeon following completion of my fellowship at Memorial Sloan-Kettering in 1995. However, the "margin call" began to drop and soon it was clear that surgeons needed only to remove all visible tumor - that is, visible by microscopic examination verified by surgical pathologists - to achieve optimal results. At first, this may seem rather cavalier, but radiation therapy, chemotherapy, and targeted therapies are as capable of driving out unwanted residual cancer cells as any knife made by man.
But a formal study of adequate margin width, with randomized clinical trials and convergence of data, have not been undertaken. (No drug company in the bleachers ready to profit from the results of such a study?) As a result, the range of opinion about the adequate distance around the tumor has, itself, remained wide.
A study of this problem, published today, just illuminates the sticky knot around this issue but fails to provide a solution to it. The illumination is as follows.
In an attempt to achieve a good, wide negative margin, many surgeons will re-operate when the original resection margins are deemed too narrow (by their individual standards.) Upon examination of a large group of surgeons, it would appear that some re-operate frequently while others take their patients back for re-excision much less often. The spotlight on the rate of re-excision falls most harshly on the surgeons who re-operate most frequently, but the truth of the problem is not to be found there, but with the ongoing lack of consensus about the definition of adequate negative margins in women undergoing lumpectomy.
To read about the study in more detail, I refer you to the excellent article published on the front page of the New York Times today. A proper evaluation of the problem, with an eye to resolving it, should fall on the shoulders of federal funding agencies. The Department of Defense just happens to have millions of dollars targeted for breast cancer research. They ought to break free a portion of that to settle this issue.
In the meantime, I shall continue to promote research on the human mammary tumor virus, thought to be involved with at least 40% of breast cancer, and the first preventive breast cancer vaccine developed by Professor Vincent Tuohy of the Cleveland Clinic TWO YEARS AGO that still awaits funding to begin Phase I studies in women.