B Prognostic Index in Determining Prognosis in Metastatic Breast Cancer.

Objective: To determine the relationship between the B2 prognostic index (B2PI) scoring method and prognosis in metastatic breast cancer, and to create a formula based on parameters that can be easily accessed in daily practice.

Study Design: Descriptive study. Place and Duration of the Study: Department of Medical Oncology, Dokuz Eylul University, Izmir, Turkiye, between May 2010 and June 2021.

Methodology: The clinicopathological characteristics of the patients were compared between the groups. All female breast cancer patients over the age of 18 years with de novo metastatic and non-metastatic breast cancers who developed metastasis during follow-up, were included in the study. Those with a second solid cancer or haematological malignancy and with a life expectancy of less than 3 months were excluded from the study. Chi-square and Fisher's exact tests were used to compare categorical data between the groups. Overall survival evaluations were made using the Kaplan-Meier analysis method and Log-Rank test. Risk factors for mortality were evaluated in Cox regression analysis. In all statistical tests, p <0.05 was considered statistically significant.

Results: There were 176 patients in this study, out of which 111 (63.1%) were de novo metastatic. When the effect of B2PI risk groups on overall survival in intrinsic subtypes was analysed, significant differences were found in the overall survival of B2PI risk groups in all subtypes except HER2+ ER- (HER2 overexpression subtype). According to the B2PI scoring system, the median overall survival was higher for both low-risk and moderate-risk patients compared to those in the high-risk category.

Conclusion: For metastatic breast cancer patients, the B2PI can be used to determine prognosis and develop treatment strategies, as it is a clinical decision-making tool based on parameters that are easily accessible in daily practice.

Key Words: Metastatic breast cancer, B2 prognostic index, Prognosis, Survival.