A biological risk profile can identify patients with ductal carcinoma in situ (DCIS) who are at high risk of recurrence and might benefit from radiotherapy following breast conserving surgery (BCS), according to findings presented at the 2016 San Antonio Breast Cancer Symposium.1
“The assay appears to be able to identify patients who have a low risk without radiation treatment, clinically-acceptable at about 10% at 10 years, but also the group we want to treat—patients who, without radiation, have a 30% risk of failure at 10 years, but who appear to do quite well with radiation,” said Pat Whitworth, MD, of the Nashville Breast Center in Tennessee.
“In the absence of something beyond clinicopathological factors, we as clinicians are not really successful at identifying patients who do not need radiation treatment,” he said. “We would like to be able to identify those patients that do not benefit from that additional treatment.”
Dr Whitworth presented the first of 3 validation studies of a new biological risk profile for patients with DCIS treated with breast conservation. The Kaiser Permanente Northwest Center for Health Research (KPNW) recently conducted a validation study of the Prelude biological risk signature for ipsilateral breast event risk following BCS. The signature integrates immunohistochemical biomarkers and clinicopathologic factors.
Eligible patients were at least 26 years old and had DCIS with no invasive components, and underwent BCS between 1990 and 2007. Radiotherapy treatment status had to be known and patients included in the study could not have prior DCIS or invasive breast cancers, systemic therapies, or radiotherapy for breast disease.
Two cohorts were analyzed: 78 patients who had undergone BCS alone (with or without hormone therapy) and 377 patients who had also received standard radiotherapy. The groups were well-balanced for extent of disease, but the no-radiotherapy cohort tended to be older and to have lower-grade disease.
When low and high biological risk scores were compared across the entire study, “low-risk identified a statistically-significant difference compared to patients with a high score” for local failure (hazard ratio, 1.87; P = 0.038), Dr Whitworth reported.
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“The main takeaway from this study is that the patients who had no radiation treatment added to their lumpectomy and who had a low score—3 or lower on the 10-point scale—had a low, clinically-acceptable risk for failure at 10 years. But even more importantly, the assay identified patients at higher risk—those patients who we want to identify for treatment, who have a 30% risk at 10 years. Those patients who had a high score and were treated with radiation had a low 10% risk of local failure at 10 years.”
Two independent validation studies are underway in Australia and Sweden. They will be completed early in 2017, he concluded.
- Bremer T, Whitworth P, Leo M, et al. DCIS biological risk profile predicts risk of recurrence after breast conserving surgery in a Kaiser Permanente NW population. Paper presented at: 39th San Antonio Breast Cancer Symposium; Dec 2016; San Antonio, TX.