Traditionally, the presence of ductal carcinoma in situ with invasive HER2-positive breast cancer has made surgeons hesitant to offer women breast conserving surgery following neoadjuvant therapy.
The concern has been that ductal carcinoma in situ (DCIS) doesn’t respond well to neoadjuvant treatment, so leaving it behind could increase the risk of recurrence.
A new study, however, calls that thinking into question.
In a nationwide review of over 5,000 women in the Netherlands,
The study is the largest look into the issue to date and confirms similar reports from a handful of smaller studies.
“These findings are important to create awareness that the presence of a DCIS component ... should not necessarily indicate the need for mastectomy,” said Roxanne Ploumen, PhD, of Maastricht (the Netherlands) University Medical Centre and colleagues.
The study was published in Breast Cancer Research and Treatment.
The research team compared biopsy results before neoadjuvant therapy with pathology reports following surgery. DCIS had a pathologic complete response rate of 52%. Neoadjuvant therapy generally consisted of anthracyclines followed by docetaxel or paclitaxel, in combination with trastuzumab.
The study also supports the assertion that women with DCIS are less likely to have breast-conserving surgery. Patients with DCIS were more likely to get mastectomies in the study (53.6% vs. 41%; P < .001) although the exact reasons are unclear because the data didn’t capture information relevant to surgical decision-making, including patient preferences and the extent of calcifications on mammography.
The key now is to find a way to assess how well DCIS responds to neoadjuvant therapy to better guide surgical decisions. Future studies should “investigate the evaluation of DCIS response by imaging” to increase the chance of breast-conserving surgery. “Moreover, a thorough investigation of pathologic characteristics” that predict response “could be useful,” Dr. Ploumen and associates said.
The investigators did find a few correlations that might help with response prediction; complete resolution of DCIS was associated with a complete response of the primary tumor to neoadjuvant therapy as well as negative estrogen receptor status and more recent breast cancer diagnosis, likely because of recent improvements in neoadjuvant therapy, including dual anti-HER2 blockade from 2017 onward, the team said.
Asked for comment, Kathy Miller, MD, a breast medical oncologist at Indiana University, Indianapolis, called the findings “interesting.”
“I suspect the challenge is that DCIS is often associated with microcalcifications” that don’t go away with therapy, “so it is common for [surgeons] to remove all areas” with microcalcifications. For now, “we can’t determine if the DCIS has” resolved with neoadjuvant therapy, so leaving calcifications behind “means accepting the possibility that you might be leaving residual disease behind,” she said.
The analysis included 5,598 women diagnosed with HER2-positive invasive breast cancer treated with neoadjuvant therapy and surgery between 2010 and 2020. The investigators coupled the Netherlands Cancer Registry with the Dutch Nationwide Pathology Databank to conduct their analysis.
About a quarter of the women had a DCIS component to their breast tumors.
The work was funded by the Jules Coenegracht Senior Foundation. Dr. Ploumen and Dr. Miller reported no conflicts of interest. Three investigators reported ties to Servier Pharmaceuticals, Bayer, Novartis, and other companies.