Analysis Predictors of the Outcome of Adjuvant of Hormone Therapy on Estrogen Receptor-positive Breast Cancer in Indonesia

Abstract

BACKGROUND: An existing study reported variation of the outcome of adjuvant hormone therapy on breast cancer. AIM: This study aimed to examine predictors of the hormone therapy to the outcome of recurrence-free survival (RFS) of estrogen receptor-positive (ER+) breast cancer. METHODS: In this cohort study, we followed up 219 eligible breast cancer patients with ER+ who had hormone therapy in 2017–2018. Age of patients, cancer stage, and various histopathology parameters were collected from the medical records, then we followed up with the patients within 2 years (2019–2020) to assess the RFS outcome. Bivariate analysis was conducted to assess the association between the clinicopathology parameters with RFS outcome. Multivariate analysis with logistic regression was also performed to see the dominant predictor. Mediation path analysis was also performed to determine the estimated effect of a predictor on the level of RFS and to see the visualization of the association of predictors with RFS. RESULTS: Breast cancer RFS was 91.3% within 2 years of hormone therapy. The recurrent rate was only 8.7%, which most of them (68.4%) were local. There was no association of age, lymphovascular invasion (LVI), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status with RFS. Based on the molecular subtype, the RFS was better in luminal A (p = 0.045), and also better gradually in the lower stage (p = 0.001). Multivariate analysis shows that the cancer stage was the dominant predictor of the RFS outcome (p = 0.001) with OR = 4.271 (Exp[B] = 1.937–9.417). Mediation analysis also found that there was a positively associated molecular subtype with RFS through cancer stage mediation (r = 16.7%, p = 0.006) but no statistically significant association of age, LVI, PR, and HER2 status (p > 0.005). CONCLUSION: Cancer stage is the main predictor of RFS of hormone therapy outcome. Luminal A is most also likely to have a better outcome of RFS, especially mediated by the lower stage.