Prognostic impact of the 8th edition of American Joint Committee on Cancer (AJCC) cancer staging system on clinically negative lymph nodes (cN0) breast cancer patients

In 2017, the 8th edition of American Joint Committee on Cancer (AJCC) Staging Manual released the updating of TNM. The new edition introduces changes concerning tumor classification that could have a real innovative and useful clinical impact. The purpose of the study is to compare anatomic vs. prognostic stage group introduced in the new edition of AJCC staging system and its importance in clinical practice. We retrospectively analyzed the prognostic stage group introduced by the 8th edition of the AJCC staging system for breast cancer. We restaged a large series of patients with infiltrative breast cancer from 2004 to 2017 applying the AJCC 8th Edition prognostic stage group criteria. This study included 1575 patients with all molecular subtypes of breast cancer. Our follow-up included disease-free survival (DFS), disease-related survival (DRS), and overall survival (OS) data. Kaplan–Meier test was used for statistical analysis. The median follow-up was 7 years. The 5-year and 10-year OS were 96% and 90%, respectively. From our analysis, according to the 8th edition, the majority of patients included in the cohort had a down-staging to a better prognostic group except the triple-negative tumors. Most of the anatomic stage IIA turned into IA and IB. This new staging system seems to better relate to prognosis. Therefore, the prognostic stage represents an important support in breast cancer management since it could avoid unnecessary and ineffective therapies; in contrast, it could help realize the global evaluation of the risk of relapse/response to specific treatments, leading to a significant reduction in the national health cost.