Objective: The current study was undertaken to determine if the CPS+EG score could stratify patients with respect to local-regional recurrence (LRR).
Background: We previously defined and validated a novel breast cancer staging system incorporating the American Joint Committee on Cancer clinical stage (CS), final pathologic stage (PS), estrogen receptor status (E), and nuclear grade (G) (CPS+EG score). The score is associated with disease-specific survival outcomes in patients treated with neoadjuvant chemotherapy.
Methods: Patients receiving neoadjuvant chemotherapy between 1997 and 2005 were identified and clinicopathologic data were used to determine the CPS+EG score. Type of local therapy, breast-conserving therapy, mastectomy alone, or mastectomy followed by postmastectomy radiation therapy was recorded. Multivariate analysis, including CPS+EG score and local therapy, was performed to evaluate for association with LRR.
Results: Of 1697 patients, breast conserving therapy was performed in 656 (39%), mastectomy in 297 (17%) and mastectomy + postmastectomy radiation therapy in 744 (44%). At a median follow-up of 49 months, the crude incidence of LRR was 6.5%. Freedom from LRR at 5 years ranged from 86% to 97% by clinical stage, 86% to 97% by pathologic stage, and 71% to 99% by CPS+EG score. On multivariate analysis, CPS+EG score and surgery type were independently associated with LRR, with increased risk among patients with CPS+EG scores of 3 or greater (HR 1.94, 95% CI 1.04-3.63) or mastectomy alone (HR 2.14, 95% CI 1.26-3.63).
Conclusions: The CPS+EG staging system better stratifies patients with respect to LRR after neoadjuvant chemotherapy than presenting clinical stage or final pathologic stage. For CPS+EG scores ≥3, use of postmastectomy radiation therapy decreases the likelihood of LRR after mastectomy.