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Less aggressive DCIS treatment increases risk for recurrence
Inadequate excision of ductal carcinoma in situ leads to recurrence or development of invasive disease in more than half of women by 10 years, according to results of a prospective database analysis presented at the American Society of Breast Surgeons Annual Meeting.
Whether ductal carcinoma in situ (DCIS) is overtreated with standard therapy has been debated.
“The DCIS controversy has been distorted in the media and many women are confused,” Sadia Khan, DO, program advisor of Hoag Breast Care Center and assistant clinical professor of surgery at Keck School of Medicine at University of Southern California, said in a press release.
“The [previous] studies themselves are valid, but much more research is needed before medical science, let alone the media, draws any hard and fast conclusions.”
Khan and colleagues reviewed database records from 720 patients (mean age, 55 years; mean tumor size, 17 mm) with DCIS and no invasion or microinvasion who were treated with excision alone.
Researchers divided patients into two groups based on margin size: those with margins less than 1 mm (n = 124) and those with a margin greater than or equal to 1 mm (n = 596). Patients with margins less than 1 mm were considered inadequately excised and advised to undergo re-excision but all refused additional treatment.
In the cohort of women with margins less than 1 mm, 69 women had nuclear grade I and II disease — considered low grade — and 55 had nuclear grade III disease, considered high grade. In the cohort with margins of 1 mm or greater, 406 had nuclear grade I or II disease and 190 had nuclear grade III disease.
The primary study measure was RFS.
“Unlike many recent DCIS studies, we focused on recurrence, not mortality as an endpoint,” Khan said. “With DCIS ... recurrence may lead to a more advanced form of breast disease, and potentially more aggressive treatment at a later date.”
Mean follow-up was 79 months.
Five-year and 10-year RFS significantly differed between patients with low-grade and high grade DCIS, and for patients with margins less than 1 mm and greater than or equal to 1 mm (P < .001).
Researchers then evaluated 5- and 10-year RFS outcomes of women within each nuclear grade according to whether they were adequately or inadequately excised.
Patients with low-grade DCIS who were inadequately excised had a higher rate of recurrence than women with wider margins at 5 years (18% vs. 8%) and 10 years (53% vs. 13%). Patients with high-grade DCIS who were inadequately excised also had a higher rate of recurrence than women with adequate excision at 5 years (55% vs. 23%) and 10 years (67% vs. 36%; P < .001 for all).
“This study clearly shows that excising DCIS with a minimum of 1-mm margin of disease-free tissue is beneficial for many women and that further study is needed before current protocols are revised,” Khan said. “Women frequently come into our practice and say they have read that DCIS does not require treatment. Clearly our study suggests this is untrue.” – by Nick Andrews
Reference :
Khan S, et al. Are we over-treating ductal carcinoma in situ (DCIS)? Presented at: American Society of Breast Surgeons Annual Meeting; April 13-17, 2016; Dallas, Texas.
Disclosure : HemOnc Today could not confirm the researchers’ relevant financial disclosures at the time of reporting.
Perspective
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The study by Khan and colleagues reopens the age-old debate about the nature of ductal carcinoma in situ (DCIS) margins, and whether this disease entity is overtreated. Their work highlights the fact that DCIS is not a singular entity, but rather a heterogeneous spectrum of disease, and although there may be some who feel that low-grade DCIS is overtreated in the current era, DCIS is not uniformly a benign entity.
Two main points become clear in this work: both biology and treatment matter. Regardless of margin width, high-grade DCIS has nearly a threefold higher chance of local recurrence at 5 years than low- to intermediate-grade disease (55% vs. 18% for < 1 mm margins; 23% vs. 8% for > 1 mm margins).
Further, margins matter. Regardless of grade, margins larger than 1 mm are associated with half the chance of local recurrence at 5 years than narrower margins (8% vs. 18% for low to intermediate grade; 23% vs. 55% for high grade).
In the SHAVE trial — published last year in the New England Journal of Medicine — we found that extent of DCIS was an independent predictor of positive margins. Hence, patients with extensive high-grade DCIS may be more predisposed to having positive margins, and may be at higher risk for local recurrence.
Given that roughly half of local recurrences of DCIS present with invasive disease, it is critical that we do not minimize the risk for this disease. DCIS is not always indolent, curable and overtreated; indeed, it can be a virulent precursor of recurrence that should not be underestimated, particularly in patients with extensive high-grade disease in whom wider margins cannot be obtained.
Reference:
Chagpar AB, et al. N Engl J Med. 2015;doi:10.1056/NEJMoa1504473.