A mid much debate about the potential for overly aggressive treatment of ductal carcinoma in situ comes a study that gives one pause. According to research presented at the 17th Annual Meeting of the American Society of Breast Surgeons, more than half of all women with ductal carcinoma in situ that was inadequately excised—which researchers considered a surrogate for surveillance as a management strategy—developed a local recurrence within 10 years of diagnosis.1
Sadia Khan, DO, Program Advisor for the Hoag Breast Care Center at Hoag Memorial Hospital Presbyterian in Newport Beach, California, said the findings are particularly significant in light of the recent message that ductal carcinoma in situ is often overtreated. “Women frequently come into our practice and say they have read that ductal carcinoma in situ does not require treatment,” she said. “Clearly, our study suggests this is untrue.”
The study’s key finding was that regardless of grade, surveillance alone, without surgical excision, is not adequate at this time, said Dr. Khan in a press briefing. “The recurrence rates for invasive and noninvasive disease are just too high…. Given our results, a watch-and-wait philosophy would be harmful for many women,” she commented.
Patients with inadequate disease-free margins had recurrence rates, 10 years after diagnosis, of 51% if they had low-grade disease and 70% if they had high-grade disease. Rates of invasive local recurrences were 26% and 31%, respectively, by grade (Table 1).
| Table: Surveillance (< 1-mm Margins) for Ductal Carcinoma in Situ (DCIS) | ||
|---|---|---|
| Tumor Grade | 10-Year Recurrence Rates | 10-Year Invasive Disease Recurrence Rates |
| Low-grade DCIS (N = 69) | 51% | 26% |
| High-grade DCIS (N = 55) | 70% | 31% |
“Doing a needle biopsy without surgical excision and following with mammography is inappropriate and unacceptable,” Dr. Khan maintained. “These patients need surgery, with good margins, with or without radiotherapy.”
Study Methods
The study explored a large prospective database of 1,919 women with pure ductal carcinoma in situ, of whom 720 were treated with excision alone (no radiation therapy). There was no strict control group of women who were observed. Instead, margin width < 1 mm was used as a surrogate for surveillance, as this is considered inadequate per National Comprehensive Cancer Network (NCCN) Guidelines. These patients had been offered re-excision but had refused, and they were therefore considered undertreated for the purpose of this study.
The inadequately excised (surveillance) group consisted of 124 patients. This group was compared with 596 patients who underwent excision with cancer-free margins ≥ 1 mm, which researchers considered an adequately treated group. The groups were also subdivided by nuclear grade—low (which also included intermediate grade) vs high.
The database was contributed by Melvin J. Silverstein, MD, a noted expert in ductal carcinoma in situ and a pioneer of the University of Southern California/Van Nuys Prognostic Index for the disease.
The endpoints were all local recurrences and invasive breast cancer recurrences. Dr. Khan considers this endpoint to be as important as overall survival; a mortality advantage would actually be difficult to show in ductal carcinoma in situ, as “survival is essentially 100%,” she pointed out.
“While mortality may not be affected by the type of treatment for ductal carcinoma in situ, we shouldn’t discredit the impact of breast cancer recurrences that can be life-threatening and often require more aggressive treatment,” she said in a press briefing.
Low Recurrence Rates With Surgical Excision
In comparison to high local recurrence rates among the inadequately treated ductal carcinoma in situ population, for women who underwent adequate excision, recurrence rates were lower: at 10 years, 13% for the low-grade group and 35% for the high-grade subset, with 10-year invasive local recurrence rates of 8% and 17%, respectively.
She added that since 10-year recurrence rates were only 13% for patients with low-grade ductal carcinoma in situ with excision ≥ 1 mm, excision alone might be acceptable for this group. “High-grade ductal carcinoma in situ cannot be treated with excision alone,” she suggested.
Surgery vs Surveillance in Ductal Carcinoma in Situ
- In an analysis of a large database of patients with ductal carcinoma in situ, researchers compared recurrence rates for women who underwent adequate excision (≥ 1-mm margins) vs those with inadequate excision (< 1-mm margins); the inadequately excised group served as a surrogate for “surveillance.”
- Patients in the surveillance group had 10-year local recurrence rates of 51% if they had low-grade disease and 70% if they had high-grade disease.
- Adequate excision was associated with local recurrence rates of 13% for the low-grade group and 35% for the high-grade subset.
- The authors maintained that surveillance is unacceptable in the ductal carcinoma in situ population.
In all the comparisons by grade, differences in recurrence rates for high-grade vs low-grade ductal carcinoma in situ were statistically significant, except for invasive local recurrence rates among the inadequately excised.
“We believe the numbers in the ‘surveillance group’ were too high to be considered acceptable,” Dr. Khan reiterated.
She added that the benefit of excision over surveillance might actually be underestimated by this study, in which the “surveillance” group actually had surgery. “If you consider true surveillance, which is needle biopsy alone and no further treatment, these patients would likely do worse than these numbers show,” she predicted. Dr. Khan acknowledged that within the realm of a clinical trial, observation may be appropriate for select patients, “but this needs to be made on a case-by-case basis.” ■
Disclosure: Dr. Khan reported no potential conflicts of interest.
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