Abstract 18P
Background
Complete cell cycle arrest (CCCA) has been regarded as a biomarker associated with endocrine responsiveness and recurrence-free survival in HR+HER2- breast cancer. We evaluated a prognostic influence CCCA in patients with HR+HER2- breast cancer who had residual tumors after neoadjuvant chemotherapy (NAC).
Methods
Between 2007 January and 2021 June, we retrospectively identified 1,178 patients with ER+HER2- breast cancer who underwent NAC in two academic institutes. Among these, 918 who had Ki67 index in surgical specimen with residual invasive cancer were included. CCCA was defined as Ki67 less than or equal to 2.7%. We investigated the recurrence-free survival (RFS).
Results
In 918 patients, the CCCA rate was 60.1% (552/918). The rate was 63.7% in grade 1/2, whereas it was 37.0% in grade 3. At a median follow-up of 57.8 months, the RFS differed significantly according to the CCCA (p<0.001); The 7-year RFS of the CCCA group was 75.8% (95% CI, 71.3-80.6%), whereas that of the non-CCCA group was 63.9% (95% CI, 58.0-70.4%). CCCA was associated with superior RFS in both grade 3 and clinical stage 3 groups. In multivariable analyses, achieving CCCA was demonstrated as a prognostic factor for RFS (hazard ratio 0.50, 95% CI, 0.37-0.67) independent of stage, age, and grade.
Conclusions
Among patients with HR+HER2- breast cancer who had residual invasive disease after NAC, achieving CCCA could serve as a significant prognostic marker.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
S.G. Ahn: Financial Interests, Institutional, Research Grant: Gencurix. All other authors have declared no conflicts of interest.