3713 - Adjuvant Systemic Therapy in Women with Early Breast Cancer and Intermediate Prosigna ROR Scores: Is Chemotherapy Use Declining? Evidence From a Large Practice

Background

Decision making on adjuvant systemic therapy in women with primary node-negative, HR+ breast cancer and intermediate risk scores on a molecular tumor profile has often been difficult, and may be based also on additional clinical factors such as age, tumor size and grade. In mid-2018 new level 1 evidence on the lack of additional benefit with chemo-hormonal therapy versus hormonal therapy for most of these patients emerged. We sought to determine if systemic adjuvant therapy choices have changed in a large community practice of over 200 medical oncologists in the U.S. using in-house tumor testing with the Prosigna PAM 50 assay. There is robust clinical evidence on recurrence risk estimation with PAM 50. Data from the ABCSG-8 estimates distant RFS of 91.3% at ten years in the intermediate risk group treated with hormonal therapy alone. Decreased chemo use would lead to decreased therapy-related toxicity and probable healthcare cost savings.

Methods

We compared Prosigna ROR results in individual postmenopausal women with HR+, node- primary breast cancers from the period 9/17 through 6/18, with the period 6/18 through 3/19. Approximately 800 total tests were run from one large practice in the U.S. About 20% fell into the intermediate score range We compared the number of patients receiving adjuvant chemohormonal therapy versus hormonal therapy alone or no systemic therapy. Physicians were polled as to whether their decisions were influenced by the ROR score, clinical factors, or both.

Results

During the period studied, the percentage of patients with intermediate ROR scores receiving adjuvant therapy declined. Physicians based their decisions on the scores primarily, along with other clinical factors. The percentages of physicians influenced by each factor and the totals for each category of treatment will be presented in the final poster.

Conclusions

Oncologists in a large practice are influenced in making breast cancer adjuvant therapy decisons by recent trial data, as well as clinical factors, and may extrapolate from one molecular profile to another. Adjuvant chemo use in HR+ node- patients is likely to remained confined to patients with a high-risk profile, regardless of the assay used.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Florida Cancer Specialists.

Funding

Has not received any funding.

Disclosure

L.L. Hart: Advisory / Consultancy, Travel / Accommodation / Expenses: Self. All other authors have declared no conflicts of interest.