Study Shows No Long-Term Benefit from Sentinel Lymph Node Biopsy

Hee Won Suh, a postdoctoral fellow in biomedical engineering, prepares a nanoparticle solution in the Saltzman Lab. Image courtesy of Andrea Ouyang

Ductal carcinoma in situ, or DCIS, makes up 20-25% of all breast cancer diagnoses in women  in the U.S. A new Yale study shows that a common intervention does not improve outcomes for women dealing with the disease. 

DCIS is classified as stage zero cancer because it is non-invasive and not life-threatening.    All the cancer cells remain within the walls of the milk ducts. It was almost never detected before the rise of mammography.   But it is possible for it to become life-threatening if it spreads through the wall of the duct and beyond the breast, though data from this latest and previous studies show the potential for such spread is low.

DCIS is commonly treated with a lumpectomy, a procedure that removes only part of the breast, and in some cases with a sentinel lymph node biopsy (SLNB) to test whether the cancer has spread. Experts do not recommend SLNB for DCIS patients because the disease is literally “in situ,” meaning in the original place, but over the years the rate of women receiving the procedure has gone up from 7.2% to 39.4%. 

Shi-Yi Wang, the lead author of the study and an associate professor at the Yale School of Public Health, says this percentage is too high. His team’s study examined not only “breast cancer mortality, since mortality for patients with DCIS is very low,” but also for rates of “mastectomy and whether or not patients develop invasive cancer in the same place” to determine is SLNB was effective. In the study, 5957 women aged 67-94 years who had already received a lumpectomy, 1992 of whom had received SLNB, were observed for up to 14 years, with a median follow-up time of 69 months. These results determined that the rate of invasive recurrence (calculated by the number of women who eventually had to get a mastectomy) and the rate of mortality were not significantly different for the patients who received SLNB and those who did not. 

Proponents of sentinel lymph node biopsy cite concerns that micro-metastases are not detectable by any other means for DCIS patients. Wang agrees, but says we “need to balance the benefits and harms” of the procedure, especially because of the low returns from the biopsies and the side effects associated with it. SLNB, though it is the “least aggressive lymph node biopsy,” can still cause pain, wound infection, and lymphedema, while not improving outcomes for older women dealing with breast cancer. 

When speaking about DCIS patients and their views on cancer, Wang acknowledges that many patients hear the word “cancer” and immediately want to receive treatment, having been conditioned to believe that “the more the procedures the better the outcome.” But it many cases, this is not true. He says, “We already over-diagnose patients with DCIS and then patients with DCIS still get over-treated.” This may be attributed to the fact that there may be a financial incentive for doctors to perform the biopsies because Medicare and Medicaid cover the costs of the procedure and because of the emotion associated with a cancer diagnosis. 

When asked about what can be done to lessen the use of this procedure, Wang replied that “publications and studies can inform surgeons” and “the media can disseminate information to inform patients.” Surgeons should be confident that it is okay to not perform the sentinel lymph node biopsy because it shows no long-term benefit and because it can cause complications. 

Overall, within the population that was studied, older women with DCIS, his team “does not find any benefit from sentinel lymph node biopsy.” However, Wang says one of the limitations of the study is that it is “not applicable to younger populations” and that in order to apply these findings to a wider subset of women with DCIS, “future study is needed.”