E. Shelley Hwang, MD, MPH
The routine use of screening mammography has drastically increased the identification of ductal carcinoma in situ (DCIS) over the past 3 decades. However, results from current research suggest that many cases of DCIS have a low risk for progression and thus may not require surgical excision and radiation therapy.
“For DCIS at low risk of progression to invasive cancer, such as low-grade, small, nonpalpable lesions, there may be no benefit to surgery and radiation, whereas for large, palpable, high-grade DCIS, intervention may prevent progression to invasive cancer,” E. Shelley Hwang, MD, MPH, wrote in the abstract for her presentation at the recent 2018 Miami Breast Cancer Conference®
Hwang, who is vice chair of research and chief of breast surgical oncology at Duke University Medical Center, Durham, North Carolina, argues that the increasing detection of DCIS due to more widespread use of mammographic screening calls for “a treatment strategy that is based on biological risk of clinically significant disease, rather than continuing to treat all DCIS as 1 disease.”
Current treatment guidelines call for a combination of surgery, radiation, and hormonal therapy for all DCIS, but risk stratification tools exist that may be of value in identifying patients who would benefit from more aggressive treatment. Oncotype DX Breast DCIS Score and DCISionRT each have the potential for treatment refinement based on risk of recurrence and invasiveness, Hwang wrote. In her presentation, she suggested that a case can be made for tailoring intervention based on age and the presence of competing comorbidities, “given the lead time between development of DCIS and progression to invasive disease.”
Hwang also discussed trials under way to test active surveillance as a moderate approach for treatment of lowest-risk DCIS. The COMET trial, for example, will assess the risks and benefits of active surveillance compared with guideline-concordant care for cases of low-risk DCIS. It is 1 of 3 prospective randomized trials that are performing this evaluation. “The overarching hypothesis of these studies is that management of low-risk DCIS using an active surveillance approach does not yield inferior oncologic or quality-of-life outcomes compared with guideline concordant care,” she wrote.
MBCC Chair Patrick I. Borgen, MD, noted that the nature of the progression of DCIS has long been misunderstood. “Our generation made an assumption that all DCIS would naturally progress into invasive breast cancer if you left it alone or if you didn’t treat it,” said Borgen, chairman of surgery and director of the Breast Cancer Program at Maimonides Medical Center in Brooklyn, New York. “We now know, based on a lot of evidence from a lot of different venues, that that simply is not true. A substantial proportion of DCIS was really never going to become an invasive, life-threatening cancer, or it was going to do so very slowly. That understanding about the basic biology of DCIS changes our approach very dramatically.” (Table
TABLE. Change in Size-Specific Incidence of Breast Cancer After Introduction of Screening Mammography
Surgery or Radiation for Low-Grade, Low-Recurrence Score DCIS?
Although early detection of DCIS enables patients to receive treatment before the cancer becomes invasive, Anees B. Chagpar, MD, MSc, MPH, MA, MBA, pointed out that some patients are treated for low-grade precancerous lesions that probably would not develop into invasive cancers or affect longevity. “If they had never known about those lesions, they could have just as well lived their life,” said Chagpar, associate professor in the Department of Surgery at the Yale School of Medicine and the assistant director for global oncology at the Yale Comprehensive Cancer Center. “Now they are undergoing all kinds of treatments for these lesions, and is that really necessary?”
Whether low-grade DCIS is overdiagnosed is hotly debated, but Chagpar said that many experts agree that DCIS is often overtreated and that further research should focus on identifying the patients who can safely avoid radiation therapy and surgery. “Certainly, we do not want to give away the advantage that we’ve got by being able to essentially cure these patients before they get invasive disease,” Chagpar said. “But at the same time, we don’t want to treat patients whose lesions would have never caused them any harm, such that the treatment may do more harm than good.”