The impact of genomic testing on the recommendation for radiation therapy in patients with ductal carcinoma in situ: A prospective clinical utility assessment of the 12-gene DCIS score result

Background and ObjectivesTwenty percent of breast cancers are ductal carcinoma in situ (DCIS), with 15-60% having a local recurrence (LR) after surgery. Radiotherapy reduces LR by 50% but has not impacted survival. The validated Oncotype DX (R) 12-gene assay (DCIS Score) provides individualized 10-year LR estimates. This is the first study to assess whether DCIS Score impacts physicians' recommendations for radiation. MethodsTen sites enrolled women (9/2012-2/2014) with DCIS eligible for breast-conserving therapy, excluding patients with invasive carcinoma and planned mastectomy. Prospective data collected included clinicopathologic factors, DCIS Score assay, and treatment recommendation before and after the assay result was known. ResultsIn 115 patients (median age: 61 years; 74.8% postmenopausal), median DCIS size was 8mm; 20% were nuclear grade 1, 46.1% grade 2; 64.4% reported necrosis. 86.1% were ER+, 79.1% PR+ (immunohistochemistry assay). Median DCIS Score: 29 (range: 0-85). Pre-assay, 73% (95%CI: 64.0-80.9%) had radiotherapy recommendations vs. 59.1% (95%CI: 49.6-68.2%) post-assay (P=0.008). Physicians rated DCIS Score as the most impactful factor in planning treatment. ConclusionsThe radiotherapy recommendation changed from pre-assay to post-assay 31.3% (95%CI: 23.0-40.6%) of the timea clinically significant change. This study supports the clinical utility of the DCIS Score and indicates that the test provides additional, individualized information on LR risk. J. Surg. Oncol. 2015 111:935-940. (c) 2015 Wiley Periodicals, Inc.