Abstract P2-08-15: Impact of OncotypeDX on treatment decision for early stage, hormone-receptor-positive breast cancer
Authors: Anastasiadou L , Schneider M , Barinoff J , Khandan F , Falk S , Thill M 
Published: May 2016

BACKGROUND and OBJECTIVE

The OncotypeDX multigene assay analyzes the individual biology of an invasive breast cancer by examining the activity of 16 breast cancer related genes and 5 reference genes in the tumour tissue. It is used in patients with early hormone-receptor-positive breast cancer with up to 3 positive lymphnodes. The results of the analysis are fed into a formula that calculates a Recurrence Score® (RS) result. The RS result is a number between 0 and 100, and can provide information about how likely your breast cancer is to recur within 10 years of diagnosis. Since becoming available, the test is successfully validated in 18 studies for both N0 and N1.

The primary study objective was to evaluate the impact of the RS on physicians' adjuvant therapy decision-making in a cohort of consecutive patients with early ER+, HER2-negative, N0/N1 (until two positive lymph-nodes) breast cancer in our multidisciplinary team (MDT). Secondary study objectives were to assess the impact of the RS on patients' decisional conflict.

PATIENTS and METHODS

This prospective clinical study was carried out in the Breast Cancer Center at the AGAPLESION Markus Hospital. 140/890 (15,7%) patients were enrolled between 02/2013 and 04/2015 with early ER+, HER2-negative (IHC or FISH), N0/N1, T1-3, histological grade 1-3. We kept records from the treatment decision before and after having the result of OncotypeDX. Further inclusion criteria were age &gt;18 years and no contraindication for receiving systemic chemoendocrine therapy. Also, the treating physician and the enrolled patient had to confirm that she was principally willing to consider her initial recommendation and decision.

Each patient's case was discussed twice within the respective institution's MDT. In the first meeting, adjuvant treatment was recommended based on available clinical and histopathological data according to the guidelines. In a second meeting, the case was rediscussed and treatment was recommended with the RS result as an additional piece of information.

RESULTS

100/140 (71,4%) patients were node negative (N0), whereas 40/140 (28,6%) were node positive (N+). Treatment recommendation changed in overall 34,3% of the cases (N0 33%, N+ 35%). In 48% of all patients (N0 43.5%, N+ 52%) with an initial recommendation for chemoendocrine therapy, the post-RS recommendation changed into endocrine therapy, in 25% (N0 30%, N+ 6.7%) of the cases with an initial recommendation for endocrine therapy only to combined chemoendocrine therapy, respectively. Only 48% of the patients with an inital endocrine therapy recommendation followed post-RS recommendation change to chemoendocrine therapy. On the other hand, 100% of the patients with an initial chemoendocrine therapy recommendation followed the post-RS recommendation change to endocrine therapy.

CONCLUSION

Our results show that OncotypeDX has an impact on the initial treatment decision on node positive as well as node negative patients. A substantial therapy change was evident in 34,3% of the cases. The data confirm, that OncotypeDX can help the doctor to formulate an individually treatment plan for patients with conflicting combination of clinical and pathological parameters.

Citation Format: Anastasiadou L, Schneider M, Barinoff J, Khandan F, Falk S, Thill M. Impact of OncotypeDX on treatment decision for early stage, hormone-receptor-positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-15.