Broad patterns of use of the gene signature panel Oncotype DX DCIS and its large-scale impact on postoperative administration of radiation therapy in women with ductal carcinoma in situ of the breast remain unclear. This study sought to evaluate the patterns of use of this gene signature panel in women with ductal carcinoma in situ and the impact of these tools on postoperative radiation therapy administration.

The National Cancer Database was queried for women with ductal carcinoma in situ treated with breast-conserving therapy who had information regarding whether a gene signature panel was performed between 2010 and 2015. Demographic characteristics, the characteristics of their ductal carcinoma in situ, and whether they received postoperative radiation therapy were compared among patients who did have a gene signature panel performed and those who did not. Patterns of radiation therapy administration were also evaluated based on the recurrence risk score by the gene signature panel.

Gene signature panel use increased over time, with a sharp increase in utilization occurring in 2015 (8.0% in 2015 vs 4.4% in 2014, P < .001). Patients with estrogen receptor–positive ductal carcinoma in situ were somewhat more likely to have a gene signature panel ordered (3.9% estrogen receptor positive vs 1.7% estrogen receptor negative, P < .001), as were patients with lower-grade ductal carcinoma in situ (4.5% grade I/II vs 3.1% grade III, P < .001). Gene signature panel utilization was associated with a decrease in the administration of postoperative radiation therapy (48.6% gene signature panel vs 83.4% no gene signature panel, P < .001). Among patients in whom a gene signature panel was performed, postoperative radiation therapy was administered in 81.9%, 72.0%, and 35.9% of patients with high-, intermediate-, and low-recurrence scores, respectively.

Gene signature panel use in patients with ductal carcinoma in situ has increased over time and is more commonly used in women with lower-risk, clinicopathologic features to determine the magnitude of benefit afforded by radiation therapy. Gene signature panel use is associated with decreased rates of postoperative radiation therapy administration, particularly among patients with scores suggesting a low rate of recurrence.