Active monitoring safe for some patients with low-risk ductal carcinoma in situ
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Key takeaways:
- Results showed a lower 2-year cumulative rate of invasive ipsilateral breast cancer among patients assigned active monitoring.
- The findings may allow for a personalized approach that avoids overtreatment.
SAN ANTONIO — Certain patients with low-risk ductal carcinoma can safely opt for active monitoring, according to study results presented at San Antonio Breast Cancer Symposium.
An analysis of patients with hormone receptor-positive, HER2-negative DCIS showed similar rates of 2-year invasive ipsilateral breast cancer recurrence among those who underwent active monitoring as those who received guideline-concordant treatment.
“These findings should help clinicians start to question what we’ve been doing for these very-good-prognosis patients,” E. Shelley Hwang, MD, MPH, vice chair of research in the department of surgery and Mary and Deryl Hart distinguished professor of surgery at Duke Cancer Institute, told Healio. “If you have a personalized approach to operating only on those patients who develop an invasive cancer, at least at 2 years, you can reduce the amount of surgery by 80%. That ultimately will be much better for patients.”
An estimated 50,000 cases of DCIS are diagnosed each year. Nearly all patients undergo surgical excision with or without radiotherapy to prevent progression.
“Because DCIS has such a good prognosis ... but does not always progress to invasive cancer, we identified an opportunity to potentially manage these patients with active monitoring,” Hwang said during a press conference.
If shown to be effective, this strategy could reduce overtreatment of women whose tumors are at low risk for progressing, as well as avoid associated adverse effects such as chronic pain, altered body image or reduced quality of life.
The prospective randomized, multicenter COMET trial included 995 patients with grade 1 or grade 2, hormone receptor-positive, HER2-negative DCIS. Trial participants had no evidence of invasive cancer.
Researchers assigned 473 patients to upfront guideline-concordant care, consisting of surgery — either breast-conserving surgery or mastectomy — with or without adjuvant radiation. The other 484 participants underwent active monitoring, which consisted of ipsilateral mammogram every 6 months and biopsy for imaging changes. Surgery was reserved for those who developed invasive breast cancer.
Patients assigned active monitoring could elect to undergo surgery at any time, and study protocol required all patients whose tumors showed signs of invasive progression to undergo surgery.
Patients in both treatment groups had the option to receive endocrine therapy.
The 2-year cumulative rate of ipsilateral breast cancer at any time after randomization served as the primary outcome.
Median follow-up was 36.9 months.
Results showed 2-year cumulative rates of invasive ipsilateral breast cancer of 5.9% (95% CI, 3.71-8.04) in the guideline-concordant care group and 4.2% (95% CI, 2.31-6) in the active monitoring group. The difference of 1.7 percentage points met the threshold for noninferiority.
A secondary endpoint focused on differences of invasive breast cancers diagnosed by randomized group. Results showed no statistically significant differences in size, HER2 status, sentinel lymph node biopsy status or the highest grade of invasive cancer diagnosed.
A slightly higher percentage of patients assigned active monitoring received endocrine therapy (71.3% vs. 65.5%). Among patients who received endocrine therapy, 2-year invasive ipsilateral recurrence rates were 7.15% among those assigned guideline-concordant care and 3.21% for those assigned active monitoring.
More than one-quarter (29.7%) of trial participants did not adhere to the treatment to which they had been randomly assigned.
Consequently, investigators conducted a separate per-protocol analysis that included 673 patients who completed their assigned treatment.
Results of that analysis showed 2-year invasive ipsilateral breast cancer recurrence rates of 8.7% (95% CI, 5.06-12.21) among those assigned guideline-concordant care and 3.1% (95% CI, 2.31-6) among those assigned active monitoring.
Researchers acknowledged study limitations, including the inability to blind treatment arms to patients or providers. In addition, although investigators observed no obvious imbalance in patient characteristics between groups, it is possible some differences were unaccounted for.
“Omission of surgery has been highly controversial, with both patients and providers fearing that it might result in an unacceptably high rate of patients who develop invasive cancer,” Hwang said in a press release. “Our findings are reassuring, and longer-term follow up will have important implications for the future inclusion of active monitoring as a treatment option for low-risk DCIS.”
Perspective
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The results provide reassurance for the short-term safety of active monitoring in patients with low-risk DCIS. Longer follow-up is needed before omitting surgery for low-risk DCIS can become standard of care, but this does provide reassurance and this approach may be appropriate for select patients — especially those who are at high risk for surgery. We also need more data on adherence to endocrine therapy in both the active monitoring and guideline-concordant care groups. The optimal duration of endocrine therapy remains in question, especially for those on the active monitoring arm. We certainly can use these data to guide very important conversations and help patients make their surgical decisions.
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Hwang ES, et al. Abstract GS2-05. Presented at: San Antonio Breast Cancer Symposium; Dec. 10-13, 2024; San Antonio.
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