LAS VEGAS – Intraoperative radiation therapy (IORT) is effective in patients with ductal carcinoma in situ (DCIS), and bilateral digital mammography and breast MRI effectively predicted which patients would be most suited for the procedure, according to a nonrandomized study.
The TARGIT-A trial showed that IORT was noninferior to external beam radiation therapy in women with early-stage breast cancer (Lancet. 2014 Feb 15;383:603-13), but the technique hasn’t been tested in DCIS patients.
Dr. Elizabeth Carlson
The researchers conducted a prospective, nonrandomized study of DCIS in women who underwent core biopsy between February 2012 and July 2016 at Virginia Mason Medical Center. Those who elected breast conserving therapy were assessed for IORT using bilateral digital mammography and contrast enhanced MRI.
For criteria, the researchers selected patients over age 44 years with unifocal DCIS and a lesion size of up to 3.0 cm. Physicians recommended additional therapy when the pathology report revealed DCIS larger than 3 cm and/or margins of up to 2 mm.
Of the 57 patients initially enrolled, 7 were found to have invasive disease and were excluded. Another eight patients were excluded because of margins, tumor size, or multifocal disease, and were recommended for additional treatment.
The remaining 42 patients with DCIS were treated with IORT. At a mean follow-up time of 32 months, the researchers observed no local recurrences, and no Radiation Therapy Oncology Group grade 3 or 4 complications were reported.
Hyperpigmentation occurred more often in the IORT group, at 40% (17 of 42 patients), than in the additional treatment group, at 13% (1 of 8), a nonsignificant difference. The hyperpigmentation tended to be minimal and focused on the surgical scar. There were no differences between the groups with respect to superficial wound separation, infection, seroma, fat necrosis, transient radiation dermatitis, or rib fracture.
“Our conclusions are that are selection criteria with mammography and MRI are effective in identifying patients who are appropriate for IORT, and importantly, at 32 months follow-up, no patients had recurrences, so we’re not negatively impacting oncological outcome,” said Dr. Carlson.
The fact that eight patients were recommended for additional treatment based on margins, a disease span greater than 3 cm, or multifocal disease “is actually quite heartening because it implies that the mammogram and the MRI are quite effective at identifying patients that met our criteria,” said Dr. Carlson.
The study is small and had no control group, but Dr. Carlson is confident of the results. “We didn’t do a randomized trial because we believed strongly that IORT will be effective in these patients with good cosmesis. When you compare it to local recurrence rates in the TARGIT-A trial, we’re still doing quite well, so to some extent that can be used as a baseline benchmark,” she said.