This article explores the findings of the COMET trial, which challenges the need for immediate surgery in low-risk DCIS cases by demonstrating that active monitoring can be equally effective.

Ductal carcinoma in situ (DCIS) has long been a clinical paradox: a non-invasive breast cancer that is managed with aggressive interventions like surgery and radiation.[1]

However, a groundbreaking study has challenged the traditional “one-size-fits-all” approach to DCIS management. By comparing active monitoring with standard surgical treatment for low-risk DCIS, results of the COMET (Comparing an Operation to Monitoring with or without Endocrine Therapy) trial provide compelling evidence that less-invasive strategies may be just as effective for certain patients.

As the era of personalised medicine continues to unfold, these findings urge us to reconsider the balance between intervention and surveillance in breast cancer care. For physicians, the question is no longer just about treating DCIS—it’s about treating the patient, informed by individualised risk profiles and emerging evidence.

@drteplinsky #greenscreen Let’s talk about this @Time Magazine cover in 2015- this was talking about omitting surgery for DCIS and we JUST saw the results of one of those studies - the COMET trial (I’ll share later this week) - 9 years later. In this video, I talk about this article - what’s changed in breast cancer and what has stayed the same and some more thoughts.

Also, I didn’t go into this in the video but I think this cover was too sensational back in 2015 and still is now. Deciding to omit surgery for DCIS is NOT “doing nothing.” The mental stress, fear, potential side effects of endocrine therapy (for HR+ disease), and increased screening are far more than “nothing.” Thoughts?! ⬇️ #dcis #breastcancer ♬ original sound - Eleonora Teplinsky, MD

About the COMET trial

The COMET trial, conducted by investigators from the Duke Cancer Institute, explored the outcomes of active monitoring vs standard treatment in women with low-risk DCIS.[2] It enrolled nearly 1,000 women and compared the incidence of invasive cancer in the same breast over 2 years.[2]

Participants were stratified into two groups: one undergoing surgery with or without radiation, and the other receiving regular imaging and clinical follow-up. Hormonal therapy was optional for both groups.[3] Preliminary results demonstrated comparable cancer rates between the groups—5.9% in the surgical cohort and 4.2% in the monitoring group. 

Treatment adaptation

Notably, 44% of participants initially assigned to surgery chose active monitoring instead, while 14% of those in the monitoring group opted for surgery. The researchers analysed outcomes based on both assigned and chosen treatments, adjusting for these shifts. Even with these variations, active monitoring did not result in a higher cancer progression rate than surgical intervention.[3]

In an interview with Time magazine, the lead author of the study, Dr. Shelley Hwang, stressed the need for extended follow-up to validate these findings and inform clinical guidelines. "This study is another important step in helping women understand that not all DCIS is the same, even though we are treating them that way," she said. "For the lowest risk DCIS like the ones in this study, surgery may not ultimately be needed.” She added that ongoing data collection at 5- and 10-year intervals will provide more definitive conclusions.

Real patient accounts

The study aligns with anecdotal evidence from patients who have chosen less invasive approaches. For example, Laura Colletti, diagnosed with DCIS in 2014, opted for active surveillance rather than surgery. Under a regimen of semi-annual mammograms and optional endocrine therapy, she remains disease-free a decade later.[3]

In the clinic

Nancy Chan, MD, a breast cancer specialist at the Perlmutter Cancer Center, told the Wall Street Journal, “This is the first study to confirm our suspicions that there’s a subset of low-risk patients that could do just as well without surgery,” adding that it’s “really encouraging.”[4] (It's important to note, however, that these patients still have a 5% risk of invasive cancer after 2 years.[3])

This approach is similar to that used for early prostate cancer, where doctors are exploring ways to reduce treatments to minimise side effects and costs for patients.[5]

Future research will investigate the role of endocrine therapy in mitigating progression risk within active monitoring protocols. Dr. Hwang’s team aims to determine whether hormonal treatment significantly reduces invasive cancer rates among women under surveillance.[3]

Disclaimer: This story is contributed by Alpana Mohta and is a part of our Global Content Initiative, where we feature selected stories from our Global network which we believe would be most useful and informative to our doctor members.