Ductal Carcinoma in Situ: Study Shows Short-Term Safety of Active Surveillance

The first study to compare surgery with active surveillance as a treatment for ductal carcinoma in situ (DCIS) concludes that women who carefully monitor precancerous cells do not develop breast cancer more often than women who undergo surgery to remove the cells after two years.

The initial results of the COMET study (Comparing an Operation to Monitoring with or without Endocrine Therapy) suggest that women and their doctors may consider active surveillance as a safe, less aggressive alternative for managing low-risk DCIS. Researchers have assumed that many women diagnosed with DCIS will not benefit from treatment, but this has not yet been tested in a clinical trial. The study results were published in the Journal of the American Medical Association (JAMA).

Ductal Carcinoma in Situ (Precancerous Condition):

Ductal carcinoma in situ (DCIS) is a tumor that is a precancerous condition of the mammary gland. Often referred to as “stage-zero breast cancer” or a “precancerous condition,” DCIS is identified by abnormal cells in the milk ducts. It does not always develop into an invasive cancer type that can spread outside of the breast. About 20% of all breast cancers are DCIS, with a peak incidence between the ages of 55 and 65. Currently, almost all women with DCIS undergo surgery, and up to one-third undergo mastectomy, which can lead to long-term symptoms and body image changes. An alternative to surgery and radiation is active surveillance, in which mammograms are routinely performed to detect changes early.

“Many women wonder, ‘Do I really want to go through this?’ when faced with surgery and possibly radiation to remove DCIS,” Hwang said. ”These initial results from our study give us confidence that active surveillance is safe in the short term and that cancers diagnosed during active surveillance are caught early.”

For the COMET study, Hwang and the research team – including co-principal investigator Dr. Ann Partridge of the Dana-Farber Cancer Institute – enrolled nearly 1,000 women aged 40 and older. After biopsy and confirmation of DCIS, the study participants were randomly assigned to two treatment groups: the current standard treatment with surgery and radiation or the alternative of active surveillance. Most women in both groups also received endocrine therapy to block the estrogen hormone that often stimulates cancer cells.

Active Surveillance, Fewer Cancers

After two years, the invasive cancer rate among women in the surgery group was 5.9%, compared to 4.2% among women who received active surveillance. Hwang said the higher rate of invasive cancer in the traditional treatment group could be the result of “upstaging,” in which invasive cancer is identified in patients diagnosed with DCIS at the time of surgery. Researchers noted that fewer cancers were diagnosed in patients who underwent active surveillance, and they believe this is due, in part, to the hormone-blocking treatment that many of them received. Although this was optional in the study, over 70% of women combined active surveillance with endocrine therapy, suggesting that this may be an important component of active surveillance for women with DCIS in the future. Both selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs) have been shown to reduce the incidence of invasive cancer by approximately 50%, with plausible mechanisms being either prevention of DCIS progression or reversal of invasive cancer.

“These initial results are provocative and potentially exciting for patients, but we clearly need more long-term follow-up,” Hwang said. If these results hold up in the long term, most patients with this type of low-risk disease have the potential to avoid invasive treatments, according to the researchers. In a separate analysis, Hwang and Partridge jointly led an additional study that measured patient-reported outcomes in both arms of the COMET trial. “The women in the study also told us how they felt over time through surveys,” said Partridge, interim chair for medical oncology at Dana-Farber Cancer Institute. Fortunately, the women’s overall health-related quality of life, anxiety, depression, worry, and symptom trajectories were comparable regardless of the treatment they received during the two-year follow-up period.