Julie Margenthaler, MD

Press briefing moderator Julie Margenthaler, MD, of Washington University Siteman Cancer Center, St. Louis, who is Communications Committee Chair for the American Society of Breast Surgeons, agreed that surveillance would be acceptable only within a clinical trial, and one is underway now. “Currently, there is a national trial of observation for ductal carcinoma in situ, and eligibility is very specific. Patients are very closely monitored,” she added.

She also noted that the study population of Dr. Khan’s analysis is different from the population of this ongoing study in that they did have surgery (but margins were narrow).

“We recommend surgery for ductal carcinoma in situ, and we recommend that patients use caution in choosing observation only, outside of a clinical trial,” she said.

Dr. Margenthaler added: “Essentially, 100% of ductal carcinoma in situ patients” have the potential for disease progression, but the actual numbers who do progress are unclear. “Whether progression happens within a woman’s lifetime or not—and to the point where it is clinically relevant—is the premise of the observational study,” she said.

Additional Commentary

Mahmoud El-Tamer, MD

Mahmoud El-Tamer, MD, a breast surgeon at Memorial Sloan Kettering Cancer Center, New York, who moderated the session where the results were presented, offered his thoughts on the findings. His main concern was that the excised and the “surveillance” groups were different in more ways than simply their margin status.

“My question is whether these patients are the same. You have a group of patients that aimed to have the same surgery, and negative margins were achieved in one group but not in another. Clearly, these are different groups,” he said in an interview with The ASCO Post.

The two groups should have also been compared for the presence of factors that would predict for recurrence, including the size of the ductal carcinoma in situ and patient age, according to Dr. El-Tamer.

“The risk in patients who were adequately excised was significantly higher, and this suggests that surgery is important,” he said. “But to enhance these results I would like to know whether there were other factors in the group with incomplete resection, beyond simply the surgery, that might also be predictive of recurrence.” ■

Disclosure: Drs. Margenthaler and El-Tamer reported no potential conflicts of interest.