Variations in histopathological and molecular subtypes between primary breast carcinoma and associated liver...

Evidence suggests that histopathological features and molecular subtypes influence the prognosis of breast carcinoma; however, their roles in liver metastatic breast cancer remain unclear. This study aimed to compare histopathological characteristics and molecular subtypes between primary breast tumors and paired liver metastases, and to evaluate their prognostic significance.

This retrospective study included 41 patients with liver metastatic breast cancer. Histopathological re-evaluation was performed for paired primary tumors and liver metastases, including tumor grade, lymphovascular invasion (LVI), lymph node (LN) status, and molecular subtype. Clinical data and liver progression-free survival (LPFS) were also analyzed. Patients were stratified according to LPFS ≤60 months and LPFS >60 months.

Patients with LPFS ≤60 months showed higher rates of LVI and positive LN metastasis in primary tumors than those with LPFS >60 months. Liver metastases from patients with shorter LPFS had a higher proportion of grade 3 tumors. Tumor grade increased in liver metastases compared with primary tumors, with grade 3 tumors accounting for 56.1% of metastases versus 22.0% of primary tumors. Overall, 39.0% of cases showed grade progression, whereas 24.4% showed molecular subtype changes. Molecular subtype composition remained largely unchanged between primary and metastatic lesions.

Histopathological discordance, particularly grade progression between primary tumors and liver metastases, may provide additional prognostic stratification beyond conventional baseline tumor characteristics. These findings highlight the importance of re-biopsy and dynamic pathological reassessment of metastatic lesions, which may directly influence therapeutic decision-making in metastatic breast cancer. Comprehensive pathological evaluation of liver metastases is recommended to guide prognosis assessment and treatment strategies.