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DCIS associated with high rates of positive margins at lumpectomy
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SAN ANTONIO — Ductal carcinoma in situ appeared associated with a higher rate of positive margins at lumpectomy than invasive breast cancer, according to study results presented at San Antonio Breast Cancer Symposium.
Among individuals with invasive disease, neoadjuvant chemotherapy receipt and seed localization were associated with lower rates of margin positivity.
“The findings were not particularly surprising,” researcher Judy C. Boughey, MD, associate professor of surgery at Mayo Clinic in Rochester, Minnesota, told HemOnc Today. “Ductal carcinoma in situ [DCIS] is much less easy to identify the extent and edges of the disease, so the higher positive margin rate in DCIS was expected.”
Negative margins significantly decrease risk for local recurrence after lumpectomy. Additionally, positive margins on final pathology require a second operation, creating an additional burden on patients and also increasing health care costs, researchers wrote.
Boughey and colleagues reviewed data on 385 lumpectomies performed between January 2012 and December 2013.
They used chi square tests, as well as univariate and adjusted multivariable logistic regression, to assess the association between rates of positive margin — defined as tumor at ink — and patient and tumor factors. Researchers stratified results based on DCIS (n = 105) or invasive disease (n = 280).
The positive margin rate at lumpectomy requiring intraoperative re-excision was 62.3% in the entire cohort. The rate was higher among those with DCIS than invasive disease (78.1% vs. 56.4%; OR = 2.78; P = .001).
Surgeon, patient age, ER status, PR status or HER-2 status did not influence positive margin rates in the overall cohort. However, univariate analysis showed high tumor grade was associated with a higher margin positive rate (grade 3 vs. grade 1, OR = 1.71; P = .049).
Among individuals with DCIS, no factors conferred statistically significant odds of positive margins on either univariate or multivariable analysis.
Among those with invasive breast cancer, univariate analysis showed the margin-positive rate was lower among patients who received seed localized excision instead of wire localized excision (48.8% vs. 60.3%). Intraoperative ultrasound and no localization also appeared associated with low margin-positive rates.
On multivariable analysis, seed localization continued to be significantly associated with reduced likelihood of positive margins compared with no localization (OR = 0.22; P = .03).
“There have been several trials comparing seed localization to wire localization,” Boughey said. “The results have varied, with some shower lower positive margins rates with seed localization and some not. Our findings are in keeping with our practice, which uses a significant volume of seed localization.” – by Jennifer Southall
Reference:
Boughey JC, et al. Abstract P1-11-08. Presented at: The San Antonio Breast Cancer Symposium; Dec. 6-10, 2016; San Antonio.
Disclosure: Boughey reports no relevant financial disclosures. Please see the abstract for a list of all other researchers’ relevant financial disclosures.