Androgen and oestrogen receptor co-expression determines the efficacy of hormone receptor-mediated radiosensitisation in breast cancer

Is neoadjuvant chemotherapy necessary for T2N0-1M0 hormone receptor-positive/HER2-negative breast cancer patients undergoing breast-conserving surgery?

INTRODUCTION

For HR-positive/HER2-negative patients who can undergo breast-conserving surgery (BCS) but have a tumor size of 2-5 cm or 1-3 lymph node metastases, neoadjuvant chemotherapy (NAC) is still controversial.

METHODS

Patients with T2N0-1M0 HR-positive/HER2-negative BC who underwent BCS between 2010 and 2017 were selected from the SEER database. Propensity score matching (PSM) was used to minimize the influence of confounding factors. The overall survival (OS) and breast cancer-specific survival (BCSS) of patients were estimated by Kaplan‒Meier curves and Cox proportional hazard models. Independent prognostic factors were included to construct a nomogram prediction model.

RESULTS

A total of 6475 BC patients were enrolled, of whom 553 received NAC and 5922 received adjuvant chemotherapy (AC). In the T2N0-1M0 population and T2N1M0 subgroup, AC patients before PSM had better OS and BCSS than NAC patients. After PSM, there was no significant difference in OS or BCSS between the two groups. However, in the T2N0M0 subgroup, there was no difference in survival between the AC and NAC groups before and after PSM. Stratified analysis revealed that for complete response (CR) patients, survival was roughly equivalent between the NAC and AC groups. However, the survival of no response (NR) and partial response (PR) patients was significantly worse than that of AC patients. Cox analysis revealed that radiotherapy after BCS was an independent protective factor for OS. NAC is an independent risk factor for NR and PR patients. The nomogram has good prediction efficiency.

CONCLUSION

NAC before BCS is not necessary for T2N0-1M0 HR-positive/HER2-negative BC patients.

Molecular subtypes of breast cancer predicting clinical benefits of radiotherapy after breast-conserving surgery: a propensity-score-matched cohort study

BACKGROUND

Based on the molecular expression of cancer cells, molecular subtypes of breast cancer have been applied to classify patients for predicting clinical outcomes and prognosis. However, further evidence is needed regarding the influence of molecular subtypes on the efficacy of radiotherapy (RT) after breast-conserving surgery (BCS), particularly in a population-based context. Hence, the present study employed a propensity-score-matched cohort design to investigate the potential role of molecular subtypes in stratifying patient outcomes for post-BCS RT and to identify the specific clinical benefits that may emerge.

METHODS

From 2006 to 2019, the present study included 59,502 breast cancer patients who underwent BCS from the Taiwan National Health Insurance Research Database. Propensity scores were utilized to match confounding variables between patients with and without RT within each subtype of breast cancer, namely luminal A, luminal B/HER2-negative, luminal B/HER2-positive, basal-like, and HER2-enriched ones. Several clinical outcomes were assessed, in terms of local recurrence (LR), regional recurrence (RR), distant metastasis (DM), disease-free survival (DFS), and overall survival (OS).

RESULTS

After post-BCS RT, patients with luminal A and luminal B/HER2-positive breast cancers exhibited a decrease in LR (adjusted hazard ratio [aHR] = 0.18, p < 0.0001; and, 0.24, p = 0.0049, respectively). Furthermore, reduced RR and improved DFS were observed in patients with luminal A (aHR = 0.15, p = 0.0004; and 0.29, p < 0.0001), luminal B/HER2-negative (aHR = 0.06, p = 0.0093; and, 0.46, p = 0.028), and luminal B/HER2-positive (aHR = 0.14, p = 0.01; and, 0.38, p < 0.0001) breast cancers. Notably, OS benefits were found in patients with luminal A (aHR = 0.62, p = 0.002), luminal B/HER2-negative (aHR = 0.30, p < 0.0001), basal-like (aHR = 0.40, p < 0.0001), and HER2-enriched (aHR = 0.50, p = 0.03), but not luminal B/HER2-positive diseases. Remarkably, when considering DM, luminal A patients who received RT demonstrated a lower cumulative incidence of DM than those without RT (p = 0.02).

CONCLUSION

In patients with luminal A breast cancer who undergo BCS, RT could decrease the likelihood of tumor metastasis. After RT, the tumor's hormone receptor status may predict tumor control regarding LR, RR, and DFS. Besides, the HER2 status of luminal breast cancer patients may serve as an additional predictor of OS after post-BCS RT. However, further prospective studies are required to validate these findings.