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.