Abstract OT1-11-01: The PREDICT registry Australia: A prospective registry study to evaluate the clinical utility of the DCISionRT test on treatment decisions in patients with DCIS following breast conserving surgery
Authors: Zissiadis Yvonne , Mann G Bruce , Shivers Steven C , Bremer Troy 
Published: March 2022

Background: The benefit of adjuvant radiation therapy (RT) for women with ductal carcinoma in situ (DCIS) treated with breast conserving surgery (BCS) remains controversial. Since there is level-I evidence supporting the role of RT in reducing the risk of local recurrence, current guidelines generally recommend adjuvant RT for all women having BCS. However, the absolute benefit of RT is variable in women with DCIS and so it is important to develop prognostic and predictive tools to better assess risk and RT benefit. The DCISionRT Test (PreludeDx, Laguna Hills, CA) is a biologic signature that provides a validated score (DS) for assessing 10-year risk of recurrence and RT benefit using individual tumor biology, as assessed by clinical and pathologic biomarkers. The primary objective of the PREDICT registries is to understand the decision impact such a tool would have on treatment decisions. Prospective Clinical Trial Design: This is a multicenter, prospective, non-interventional (observational) cohort study for women diagnosed with DCIS of the breast. After diagnosis of DCIS, sites will send the most representative tissue block or sections mounted on charged slides to PreludeDx for DCISionRT testing. Treating physicians complete a treatment recommendation survey before and after receiving DCISionRT test results. Test results, treatment recommendations, patient preferences and clinicopathologic features will be stored in a de-identified registry for participating institutions from a variety of geographic regions across Australia. Women will then be followed for up to 10 years with completion of a follow-up form. The study has been approved by the North Shore Local Health District Human Research Ethics Committee, St Leonards, NSW, Australia. Universal Trial Number (UTN): U1111-1266-0439; ANZCTR: ACTRN12621000695808; ClinicalTrials.gov: NCT04916808. Eligibility Criteria: The study includes females age 26 or older who are candidates for BCS and eligible for RT and/or systemic treatment. Subjects must not have been previously treated for DCIS or have previous or current invasive or micro-invasive breast cancer. Specific Aims: The primary endpoints are changes in treatment recommendations for surgical, radiation and hormonal therapy. Secondary endpoints are identification of key drivers for treatment recommendations, including age, size, grade, necrosis, hormone receptor status and patient preference. Statistical Methods: Changes in pre- and post-DCISionRT treatment recommendations will be analyzed using McNemar's test (alpha level = 0.05). Multivariate logistic regression will be used to determine odds ratios of clinicopathologic factors leading to pre- and post-test treatment recommendations. Pre-test covariates include patient age, tumor size, palpability, margin status, hormone receptor status, nuclear grade, tumor necrosis, family history of breast cancer, race, ethnicity and patient preference, as well as physician specialty (surgeons vs. radiation oncologists) and post-test covariates will also include the DCISionRT Decision Score (DS). Differences in recurrence-free and overall survival will be assessed by Kaplan-Meier survival analysis using the log-rank test and/or the Cox Proportional Hazards model. Statistical analyses will be carried out using R (https://www.r-project.org) or SAS. An early interim analysis based on the first 200 enrolled patients is planned. Present and Planned Accrual: We are planning to enroll up to 1,500 women from up to 100 sites across Australia. A similar registry in the US has enrolled 1,985 women from 64 sites towards a goal of 2,500.

Citation Format: Yvonne Zissiadis, G Bruce Mann, Steven C Shivers, Troy Bremer. The PREDICT registry Australia: A prospective registry study to evaluate the clinical utility of the DCISionRT test on treatment decisions in patients with DCIS following breast conserving surgery [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-11-01.