Cerebellar preference of luminal A and B type and basal ganglial preference of HER2-positive type breast cancer-derived brain metastases

Pathological Complete Response as Outcome Modifier in Breast Cancer Patients and Brain Metastasis

Breast cancer with brain metastases (BCBM) has dreadful outcomes. Various factors influencing outcomes are age, receptors status, number of distant metastases, performance status, leptomeningeal metastasis, chemotherapies, and whole brain radiation dose. This study aimed to find outcome-modifying factors in BCBM. Clinical, demographic, subtype, and pathological response of primary brain imaging characteristics of BCBM patients were correlated with brain metastasis-free interval and survival after brain metastasis was studied from January 2020 to March 2022. Triple-negative breast cancer (TNBC) patients had the earliest presentation for brain metastases (mean 45.4 years) vs luminal B (mean 57.93 years). Both brain metastasis-free interval (BMFI) and brain metastasis overall survival (BMOS) were maximum in HER2-positive subtype (mean 22.8 and 11.55 months) and least in TNBC patients (mean 9.8 and 2.12 months), respectively. Low-graded prognosis assessment (GPA) score and leptomeningeal metastasis were associated with the worst outcomes. BMFI and BMOS in patients with pathological complete response (PCR) were at 28.5 and 15.1 months, in partial response were 18.5 and 7.66 months, and with stable or progressive disease were 11 and 1.36 months, respectively. In the present study, PCR was the only modifiable parameter that changed breast cancer outcomes with brain metastasis and leptomeningeal metastasis was associated with the worst outcomes. Our study favors that PCR has prognostic importance.

An Insight into Molecular Targets of Breast Cancer Brain Metastasis

Brain metastasis is one of the major reasons of death in breast cancer (BC) patients, significantly affecting the quality of life, physical activity, and interdependence on several individuals. There is no clear evidence in scientific literature that depicts an exact mechanism relating to brain metastasis in BC patients. The tendency to develop breast cancer brain metastases (BCBMs) differs by the BC subtype, varying from almost half with triple-negative breast cancer (TNBC) (HER2^- ER^- PR^-), one-third with HER2⁺ (human epidermal growth factor receptor 2-positive, and around one-tenth with luminal subclass (ER⁺ (estrogen positive) or PR⁺ (progesterone positive)) breast cancer. This review focuses on the molecular pathways as possible therapeutic targets of BCBMs and their potent drugs under different stages of clinical trial. In view of increased numbers of clinical trials and systemic studies, the scientific community is hopeful of unraveling the underlying mechanisms of BCBMs that will help in designing an effective treatment regimen with multiple molecular targets.