Abstract 189P
Background
Hormone replacement therapy (HRT) is a risk factor for breast cancer (BC). The characteristics and prognosis of HRT-related BC are not well known. We have evaluated the characteristics and prognosis of BC in a cohort of Korea patients who have experienced HRT.
Methods
We analyzed 17,355 postmenopausal BC patients using the Korea Breast Cancer Society database from 2000 to 2014. Clinicopathologic characteristics and overall survival (OS) rate were compared between HRT group and non-HRT group.
Results
Of the 17,355 patients, 3,585 underwent HRT before BC diagnosis. The HRT group had smaller tumor, lower histologic grade, more stage I (43.8% vs 39.0%, P < 0.001) and more breast conservation surgery (60.7% vs 54.1%, P < 0.001) than the non-HRT group. The rate of progesterone receptor-negative (55.6% vs 53.0, P=0.006) and Human epidermal growth factor receptor-2-negative (73.2% vs 70.6%, P=0.004) in the HRT group were higher than in the non-HRT group and no difference in immunohistochemistry (IHC) subtype between two groups (P =0.279) Also, compared to the non-HRT group, the HRT group had more normal body mass index (BMI) (36.8% vs 31.1%, P < 0.001) and fewer obese patients (34.5% vs 43.1%). Screening (78.4% vs 59.7%, P < 0.001) and hysterectomy rate (18.0% vs. 10.3%, P < 0.001) of the HRT group was higher than non-HRT group, however there was no difference in family history (P =0.913). The prognosis of the HRT group was better than that of the non-HRT group (5-year OS rate : 93.9% vs 87.1%, 10-year OS rate : 91.7% vs 82.3%, P < 0.001) and hazard ratio of HRT group was 0.7 (95% CI 0.608-0.805, P < 0.001). In the case of screening, OS rate of HRT group was higher than that of non-HRT group (P=0.017). However, when no screening was performed, there was no difference in OS rates (P=0.054). The normal and over BMI of HRT group were better prognosis than non-HRT group (P < 0.001, P = 0.002). HRT group had a higher OS rate than the non-HRT group in luminal B and TNBC (P < 0.001, P =0.003) and had a better prognosis for all HRT duration (P < 0.001). There was no significant difference in OS rates for hysterectomy and family history (P =0.720, P =0.922).
Conclusions
The clinicopathologic characteristics of the HRT group in this study were associated with the prognosis of BC. Patients in the HRT group had favorable clinicopathologic characteristics and a better OS than the non-HRT group. BC patients who have experienced HRT may be associated with a better prognosis according to BMI subtype, IHC subtype, screening subtype and HRT duration.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.