Clinicopathological features and survival outcomes in bone-only metastatic breast cancer patients stratified by hormone receptor status: a tertiary care study

Background: Bone metastatic disease is common across all breast cancer subtypes. Patients with hormone receptor (HR)-positive breast cancer tend to have the greatest predilection for developing bone metastases and have better survival outcomes; unlike organotypic metastasis to visceral organs in triple-negative breast cancer. In this retrospective study, we compared the features and survival of these bone metastatic breast cancer subgroups and demonstrated that different ER and PR statuses contribute to varied survival outcomes. Methods: It was a single‑institute retro prospective study. Out of the 200 HPR-proven cases of breast carcinoma, 100 patients were eligible for the study who presented/developed bone metastases. Patients with visceral mets were excluded from the study. Based on ER, PR and HER2 neu, status patients were divided into four groups. Results: Out of 100 patients taken for this study 45 were ER+ PR+, 20 were Er-,PR-, 18 were ER-, PR +, and 17 were ER+,PR-.and the mean age in the study groups was 49.5±.5. Higher tumour grade and lymph node positivity was observed in ER- PR- and ER- PR+ as compared to hormone-positive groups. In our study group percentage of bone mets was higher in ER +, PR+(31.11 ) and ER+ PR- (52.63%),While as it was similar in Er-,PR- and ER-, PR + patients. The overall survival of ER+ PR- was 94.1% followed by ER +, PR+(86.7%) while patients with ER-, PR- had 30.0% and ER-, PR + 27.8%. Conclusions: Different ER and PR statuses in breast cancer exert a significant impact on bone metastasis incidence and survival condition of bone metastatic breast cancer. Hormone receptor‑positive tumours show a predilection for bones as the first site of relapse and better overall survival as compared to hormone‑receptor‑negative tumours.