Experts Tackle the Challenge of Managing Ductal Carcinoma In Situ
One of the controversies in oncology today concerns how to treat ductal carcinoma in situ (DCIS), a common pre-cancer of the breast that accounts for at least 20 percent of all breast cancer diagnoses. Nearly 100 percent of patients with DCIS achieve long-term disease-free survival with current therapies. NCI and NIH’s Office of Medical Applications of Research convened a state-of-the-science conference titled, “Diagnosis and Management of Ductal Carcinoma In Situ” 2 weeks ago, which brought together researchers, clinicians, advocates, and policymakers to discuss some key questions about this condition.
The draft conference statement, produced by a panel of 14 experts and delivered by chair Dr. Carmen Allegra of the University of Florida Shands Cancer Center at Gainesville, was intended “to provide health care providers, patients, and the general public with a responsible assessment of currently available data.” The statement addressed most of the dilemmas and included the panelists’ recommendations about how they should be handled. Questions addressed by the panel were prompted by an evidence-based report compiled by the Agency for Healthcare Research and Quality.
Perhaps the most animated discussions at the meeting were about whether the condition should be called something other than DCIS, since the fear and stigma associated with breast cancer can compromise a health provider’s efforts to explain the diagnosis and guide patients to an informed decision about treatment choices. Despite dramatically higher cure rates than invasive breast cancer (IBC) and excellent prognoses after treatment, women with DCIS experience psychological responses (e.g., anxiety and worry) similar to those experienced by women diagnosed with invasive disease.
The panel concluded that “strong consideration should be given to elimination of the use of the anxiety-producing term ‘carcinoma’ from the description of DCIS,” though Dr. Allegra emphasized it was not their charge to suggest an actual change of nomenclature and felt that pathologists would be an important constituency to consult on this issue.
The heart of the DCIS dilemma stems from the rise of screening mammography; in the 1970s, DCIS accounted for less than 5 percent of cancer diagnoses. With the addition of mammography and magnetic resonance imaging (MRI), much more disease is being detected today, and the incidence of DCIS is growing faster than that of any other breast cancer subtype.
While the natural history of DCIS is poorly understood, low-grade disease can persist for more than 4 decades without progressing, said Dr. D. Craig Allred, director of breast pathology at the Washington University School of Medicine in St. Louis. Left untreated, however, “the few studies that have been done suggest that about 35 percent of DCIS cases will progress to IBC within 30 years, and there’s actually reason to think that the real incidence of DCIS that progresses to IBC is even higher.”
The panel acknowledged that the majority of treated DCIS lesions will not progress to IBC, but Dr. Allred points out that “unless you know which ones those are, all are potentially threatening.” In addition to routine mammorgraphy, MRI is used increasingly to screen for breast cancer, and in terms of DCIS the panel asked, “To what degree does breast MRI in this setting result in overdetection, meaning the detection of biologically insignificant lesions?”
Most women with DCIS elect to have some form of surgery, given the risk of progression and their fear of invasive disease. Approximately one in three patients elect to have a mastectomy and some also have the other breast removed as a preventive measure (prophylactic mastectomy). The alternative is a local excision (lumpectomy), often followed by radiation therapy and, in estrogen receptor-positive DCIS, tamoxifen or aromatase inhibitor therapy to prevent recurrence.
Currently, it is unclear whether all patients “uniformly benefit from these interventions [and] important therapeutic questions remain unanswered,” wrote the panel. “[R]esearch efforts should focus on the identification of patients who are at high risk for developing recurrence.” They added that “the appropriate investigation of biomarkers could be helpful in guiding both systemic and local treatment decisions.”
The panel also called for better decision-making tools, which will help address patient anxiety related to the diagnosis of DCIS, the complex choice of treatment options, and “misperceptions regarding outcomes and risks of therapy.”