The AJCC 8th edition requires cancer registries in the United States to use the Prognostic Stage Grouping system for breast cancer. Prognostic stage groups use the traditional anatomic T, N, and M classifications along with tumor grade, HER2/ER/PR status, and Oncotype Dx recurrence score to classify patients into a Prognostic Stage Group. This patient's anatomic stage group is IIA. However, patients with pT1-2N0 tumors with an Oncotype Dx recurrence score <11 that are grade 1-3, HER2 negative, and ER positive are stage IA. PR status can be positive or negative.
For details of the prognostic stage grouping system for breast cancer, please refer to the AJCC Cancer Staging Manual, 8th edition.
Clinical pearl: AJCC 8th edition utilizes Grade, HER2/ER/PR status, and Oncotype Dx recurrence score to classify patients into a Prognostic Stage Group. Anatomic Stage Group is only based on the TNM classification. The anatomic and prognostic stage groups may differ.
Source: AJCC Cancer Staging Manual, 8th edition