Abstract P5-18-12: Effectiveness of Oncotype DX DCIS scoring in a community setting

Abstract

The Oncotype DX DCIS Score was developed to assist in determining a low risk for recurrence subgroup of patients who can avoid radiation therapy following breast conserving surgery. We sought to evaluate our experience using the Oncotype DX DCIS Score and to see if a greater number of patients who did not receive radiation therapy were experiencing a local recurrence than the score predicted. Between February 23, 2011 and November 29, 2017, 145 women were diagnosed with ductal carcinoma in situ (DCIS) without an invasive component. 126 (87%) underwent breast conserving surgery. Thirty-five underwent Oncotype DX DCIS Score, of whom 26 (74%) were low risk, four were intermediate risk (11%), and five were high risk (14%). The scores ranged from 0 (7 patients) to 100 (1 patient). Of the 26 patients with low risk scores, one chose to undergo mastectomy, three received radiation therapy, 20 chose observation without radiation therapy, and two patients were unknown because they had no further treatment or follow-up at our facility. Two of the four intermediate risk patients underwent radiation therapy and two did not. Four of the five high risk patients underwent radiation therapy, but one did not. Twenty-two of the 35 patients who underwent Oncotype DX Score met the criteria for size (based on grade) and margins (at least 3 mm). Ten patients had margins that were less than 3 mm but met the size criteria. Two patients did not meet the size criteria but had at least 3 mm margins. One patient did not meet either the size or margin criteria. None of our 20 patients with low risk Oncotype DX DCIS Score and who met both the size and margin criteria recurred. With the median follow-up of approximately 2-1/2 years, three of the 21 patients (14%) with low or intermediate risk scores who underwent Oncotype DX DCIS Score and did not receive radiation therapy suffered a local recurrence. The predicted average recurrence risk for these patients based on their Oncotype DX DCIS Score was 12%. Two of these patients who recurred had margins less than 3 mm, and one patient met the size and margin criteria, but had an intermediate risk score. By comparison, five of 61 (8%) of patients who underwent breast conserving surgery and adjuvant radiation therapy had a local recurrence. Twenty of the 23 (87%) low risk Oncotype DX DCIS Score patients did not receive radiation therapy and overall 20/35 (57%) of the patients undergoing Oncotype DX DCIS Score did not receive radiation therapy. Although the follow-up is still relatively short, Oncotype DX DCIS Score allows a considerable number of women to avoid adjuvant radiation therapy. Citation Format: Wheeler JA, Vaghefi H, Liu F, Owens V, Morris L, Denham F, Coody L. Effectiveness of Oncotype DX DCIS scoring in a community setting [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-18-12.