Abstract P2-03-05: AJCC prognostic stage including oncotype DX®RS: Impact on breast cancer staging compared with traditional anatomic TNM stage

Abstract

Abstract INTRODUCTION The recently published AJCC Cancer Staging Manual 8th edition, scheduled to be adopted into clinical practice in January 2018, proposes a new breast cancer (BC) Prognostic stage that includes histological grade, estrogen receptor (ER), progesterone receptor (PR), and HER2 status in addition to the traditional Anatomic TNM stage. In a further modification, patients with ER positive, HER2 negative, lymph node negative BC and an Oncotype DX® recurrence score (RS) of less than 11 will be assigned to Prognostic stage 1A irrespective of histological grade and size (up to 5cm). The changes have been proposed in recognition of the prognostic influence of these parameters and in attempt to improve personalised patient care. The aim of this study is to profile the impact on staging by comparing Prognostic stage, with and without RS, to traditional Anatomic stage, in a series of patients with early BC and an RS of less than 11. METHODS The study population comprised 127 patients with primary BC and an RS of less than 11, derived from a consecutive series of 729 patients with ER positive, Her2 negative, lymph node negative, primary BC whose tumors were tested using the Oncotype DX® multigene assay between November 2011 and December 2016. The median patient age was 57 years (35-78). Pathological tumour size was T1a (n=2), T1b (n=19), T1c (n=79) and T2 (n= 27). Median tumor size was 15mm. Histological tumour grade was grade 1 (n=14), 2 (n=98) and 3 (n=15). Each patient was assigned an Anatomic and Prognostic stage, with and without RS modification, according to the AJCC Classification of Cancer Staging, 8th edition. The three staging categories were compared and the impact on stage profiled. RESULTS Applying the traditional Anatomic Stage (TNM), 100 patients were assigned to stage IA (T1N0) and 27 patients to stage IIA (T2N0). Applying the Prognostic stage (without RS) 89 patients were assigned to stage IA, 33 to stage IB, four to stage IIA, and one to stage IIB. All patients were assigned to stage IA according to the Prognostic stage that includes a RS of < 11. Comparing Prognostic stage without RS to traditional Anatomic stage, 26.7% of patients (n=34) underwent a change in stage, 9.4% (n=12) to a higher stage and 17.3% (n=22) to a lower stage. 21.3% (n=27) of patients were down staged when comparing Prognostic stage including RS to traditional Anatomic stage. Comparing Prognostic stage including RS to Prognostic stage without RS, 29.9% (n=38) of patients were down staged. CONCLUSION Breast cancer staging is an important tool in guiding patient management. This study demonstrates that the introduction of the Prognostic stage and the modified Prognostic stage to include RS will alter the assigned stage in approximately 25% of patients with early BC. REFERENCE Edge SB, Greene FL, Byrd DR, Brookland RK, Washington MK, Gershenwald JE et al (2016). AJCC Cancer Staging Manual, 8th edn. Springer, Chicago. Citation Format: O'Cearbhaill RM, Gannon JM, Devane LA, Prichard RS, Walshe J, McDermott EW, Quinn CM. AJCC prognostic stage including oncotype DX®RS: Impact on breast cancer staging compared with traditional anatomic TNM stage [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-03-05.