15: Oncotypedx Testing Does Not Appear to Benefit Patients with Grade 1, Progesterone Receptor Positive Breast Cancers: A Tailorx Validated Study

Saturday, March 12, 2022

9:06 AM – 9:12 AM CST

Location: Chantilly East

Abstract Presenter(s)

Udai S. Sibia, MD MBA

General Surgery Resident
Anne Arundel Medical Center
Annapolis, Maryland, United States

Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Participants should be aware of the following financial/non-financial relationships:

Udai S. Sibia, MD MBA: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Introduction:

We previously described a validated (AAMC) risk prediction model, based on pathology, which may eliminate the need for OncotypeDX testing in select low-risk tumors. This previous study examined breast cancer specific survival and overall survival, but was limited by our inability to assess distant recurrence-free interval (DRFI) and invasive disease-free survival (IDFS). The purpose of this study was to validate the AAMC model using the TAILORx database and examine DRFI and IDFS.

Methods:

The TAILORx trial data was queried and patients were categorized into groups based on the AAMC model (Table 1). Low-risk tumors were both grade 1 and PR positive, while high-risk were grade 3 or estrogen (ER) negative/PR positive. All other tumors were intermediate-risk. The AAMC model recommends against OncotypeDX testing in low-risk, but recommends testing in intermediate- or high-risk. Kaplan-Meier curves were used to examine DRFI and IDFS.

Results:

Of 9143 patients, 24.6% were AAMC low-risk, 57.9% were intermediate-risk, and 17.5% were high-risk. In the low-risk cohort, 22.3% had Recurrence Score (RS) 0-10 and thus did not receive chemotherapy, while 75.3% had RS 11-25 and were randomized to chemotherapy versus no-chemotherapy, and 2.4% had RS > 25 and received adjuvant chemotherapy. In low-risk tumors, DRFI did not differ for patients who received adjuvant chemotherapy versus those that did not (log-rank p=.96). Similarly, IDFS was comparable between the chemotherapy and no-chemotherapy groups (log-rank p=.66). Only 2.4% of low-risk tumors were categorized as high-risk per OncotypeDX testing (RS > 25). A sensitivity analysis was performed in which low-risk tumors with RS > 25 were re-classified into the no-chemotherapy group and assumed to have experienced recurrences at rates expected without chemotherapy. Despite this, there was no difference in DRFI (log-rank p=.16) between groups.

Conclusions:

This study validates our recommendation that OncotypeDX testing may be omitted in early-stage breast cancers that meet AAMC low-risk criteria. By these criteria, 1 in 4 TAILORx participants do not need OncotypeDX testing.

Learning Objectives:

Upon completion, participant will be able to describe a validated AAMC model to determine the benefit of OncotypeDX testing.
Upon completion, participant will be able to identify AAMC low-risk tumors in which OncotypeDX testing may be omitted.
Upon completion, participant will be able to describe the distant recurrence-free interval and invasive disease-free survival for tumors based on the AAMC risk model.