Durham Reporter

The first study to compare surgery with active monitoring for ductal carcinoma in situ (DCIS) suggests that women who choose careful observation are not at increased risk of developing breast cancer within two years compared to those who undergo surgery. These findings come from the Comparing an Operation to Monitoring with or without Endocrine Therapy (COMET) study.

Co-principal investigator E. Shelley Hwang, M.D., of the Duke Cancer Institute, presented the early results on December 12 at the San Antonio Breast Cancer Symposium. The study is also published in the Journal of the American Medical Association (JAMA).

DCIS, often referred to as "stage-zero breast cancer" or "precancer," involves abnormal cells within milk ducts and does not always progress into invasive cancer. It accounts for about one in five new breast cancer cases annually in the U.S., affecting over 50,000 women each year.

Currently, nearly all women diagnosed with DCIS receive surgical treatment, with up to one-third undergoing mastectomy, which can lead to long-term effects and altered body image. Active monitoring offers an alternative by routinely performing mammograms to detect early changes.

Hwang stated, “Many women wonder – ‘Do I really need to do this to myself?’ – when they’re faced with surgery and possibly radiation to remove DCIS.” She added that these early results provide reassurance that active monitoring is safe short-term and that cancers detected during this period are identified at an early stage.

Involving nearly 1,000 women aged 40 and above, participants were divided into two groups: standard care involving surgery and radiation or active monitoring. Most participants also received endocrine therapy aimed at blocking estrogen hormones that fuel cancer cells.

After two years, invasive cancer rates were slightly higher in the surgery group (5.9%) compared to those under active monitoring (4.2%). Hwang suggested this might be due to "upstaging," where invasive cancer is discovered during surgery among patients initially diagnosed with DCIS.

“We noted there were fewer cancers diagnosed in those patients who had active monitoring,” said Hwang. Over 70% combined active monitoring with endocrine therapy, indicating its potential importance for future DCIS management.

Selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs) have shown a reduction in invasive cancer incidence by about 50%, potentially preventing DCIS progression or reversing invasive cancer.

“These early results are provocative and potentially exciting for patients,” said Hwang. “If these results hold up over time, most patients who have this type of low-risk disease will have the option of avoiding invasive treatments.”

In a separate analysis led by Hwang and co-principal investigator Ann Partridge, M.D., patient-reported outcomes indicated comparable health-related quality of life between both treatment groups over two years.

“The women in the study also told us in surveys how they felt over time,” Partridge noted. “Fortunately, the overall health-related quality of life... was comparable regardless of the treatment received.”

Authors from Duke involved in this research include Thomas Lynch, Marc D. Ryser, Lars Grimm, Jeffrey Marks, Rachel Factor, and Yan Li. The COMET study was supported by Alliance Foundation Trials along with funding from several organizations including Patient-Centered Outcomes Research Institute and Breast Cancer Research Foundation.