Genomic Assays in Ductal Carcinoma In Situ: Implications for Management Decisions.

Objectives: Breast cancer is the most common cancer in women and a leading cause of cancer death worldwide. The management of breast cancer depends on clinical and pathologic prognostic factors that help guide patient treatment. Ductal carcinoma in situ (DCIS) is a noninvasive form of breast cancer with an unpredictable risk of either progression to invasive disease or recurrence. To evaluate the utilization of the DCIS score in a large single-institution population and understand reasons for avoidance in eligible patients.

Methods: A retrospective chart review of eligible patients with pure DCIS treated by lumpectomy (January 2011-May 2015) was performed. Patients were considered eligible for the assay if they met the Eastern Cooperative Oncology Group E5194 pathology criteria. All of the patients underwent breast-conserving surgery and were estrogen receptor positive.

Results: Of 182 estrogen receptor-positive patients with DCIS who underwent breast-conserving surgery, 31 (17%) had a DCIS assay performed; however, most of the patients did not have a DCIS score assay performed, yet 47.9% of this cohort would have met the pathologic eligibility criteria. Conversely, 82.5% of the patients having the DCIS score evaluated actually met these criteria.

Conclusions: Tumor size, grade, ER status, and calcifications were drivers of patient selection for 12-gene assay use. E5194 eligibility criteria selected for low risk population. Although a large proportion of patients met eligibility criteria, DCIS Score was infrequently considered for recurrence risk estimation. When performed, assay scores supported omission of radiation for over 75% of cases.