Utility of the CPS plus EG scoring system in triple-negative breast cancer treated with neoadjuvant chemotherapy

Background: Pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) is associated with superior survival. This association is strongest in triple negative breast cancer (TNBC). The CPS + EG system, based on pre-treatment clinical (CS) and post-treatment pathological stage (PS), oestrogen-receptor status (E) and grade (G), leads to a refined estimate of prognosis after NACT in all-comers and hormone receptor-positive/ human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Here, we investigate if CPS + EG scoring provides a superior estimate of prognosis in TNBC to select patients for postneoadjuvant therapy. Methods: We calculated the CPS + EG score for 1795 patients with TNBC from 8 prospective German trials. Five-year disease-free survival (DFS) and overall survival estimates were calculated using the Kaplan-Meier method. Results: In TNBC, patients with pCR (ypT0/is ypN0, n = 822, 45.8%) had a 5-year DFS of 86%, whereas patients with residual American Joint Committee on Cancer stage I disease (n = 383; 21.3%) had a 5-year DFS of 77.5%.CPS + EG led to superior prognostic information compared with that provided by the clinical stage, but it was inferior to the prognostic information provided by the pathological stage (c-index statistics, p < 0.001). CPS + EG did not discriminate prognosis within the two best prognostic groups (score 1 and 2; n = 362; 37.2%). In contrast, pCR status added prognostic information beyond CPS + EG. Patients with a CPS + EG score of 3 had a 5-year DFS rate of 64% overall, but those with pCR had a 5-year DFS rate of 84%, and those without pCR had a 5-year DFS rate of only 49.7%. Conclusions: In TNBC, CPS + EG scoring provided inferior prognostic information compared with the pathological stage and was unable to identify patients without pCR and with a sufficiently good prognosis, who could avoid postneoadjuvant therapy. pCR remains the strongest and most clinically useful prognostic factor after NACT. Other biologic factors beyond pCR are needed in TNBC. 2021 Elsevier Ltd. All rights reserved.

Automated summary

In triple negative breast cancer, pathological complete response is associated with superior survival. The CPS + EG system provides refined estimate of prognosis but is less superior compared to pathological stage. Pathological complete response remains the strongest and most clinically useful prognostic factor after neoadjuvant chemotherapy.