Prognosis of synchronous bilateral breast cancer: a review and meta-analysis of observational studies

TY - JOUR

T1 - Prognosis of synchronous bilateral breast cancer

T2 - a review and meta-analysis of observational studies

AU - Holm, Marianne

AU - Tjønneland, Anne

AU - Balslev, Eva

AU - Kroman, Niels

PY - 2014/8

Y1 - 2014/8

N2 - Currently, no consistent evidence-based guidelines for the management of synchronous bilateral breast cancer (SBBC) exist and it is uncertain how presenting with SBBC affects patients' prognosis. We conducted a review of studies analyzing the association between SBBC and prognosis. The studies that reported adjusted effect measures were included in meta-analyses of effect of bilaterality on breast cancer mortality. From 57 initially identified records 17 studies from 11 different countries including 8,050 SBBC patients were included. The quality of the studies varied but was generally low with small sample sizes, and lack of consistent, detailed histo-pathological information. When doing meta-analysis on the subgroup of studies that provided adjusted effect estimates on breast cancer mortality (nine studies including 3,631 SBBC cases), we found that bilaterality in itself had a negative impact on prognosis after adjustment for known prognostic factors (pooled HR 1.37, 95 % CI 1.24-1.50, p < 0.0001). Multiple sensitivity analyses indicated robustness of the overall estimate. This review summarizes the current evidence of the association between SBBC and prognosis. The previously accepted convention that appropriate adjuvant treatment can be determined by considering the higher risk cancer was not confirmed in this review; rather it seems that being diagnosed with two tumors simultaneously entails a worse prognosis above and beyond that of the unilateral cancers of the same stage. To determine the true association between SBBC and breast cancer prognosis, studies of large and updated samples of SBBC should be done and include thorough histo-pathologic information.

AB - Currently, no consistent evidence-based guidelines for the management of synchronous bilateral breast cancer (SBBC) exist and it is uncertain how presenting with SBBC affects patients' prognosis. We conducted a review of studies analyzing the association between SBBC and prognosis. The studies that reported adjusted effect measures were included in meta-analyses of effect of bilaterality on breast cancer mortality. From 57 initially identified records 17 studies from 11 different countries including 8,050 SBBC patients were included. The quality of the studies varied but was generally low with small sample sizes, and lack of consistent, detailed histo-pathological information. When doing meta-analysis on the subgroup of studies that provided adjusted effect estimates on breast cancer mortality (nine studies including 3,631 SBBC cases), we found that bilaterality in itself had a negative impact on prognosis after adjustment for known prognostic factors (pooled HR 1.37, 95 % CI 1.24-1.50, p < 0.0001). Multiple sensitivity analyses indicated robustness of the overall estimate. This review summarizes the current evidence of the association between SBBC and prognosis. The previously accepted convention that appropriate adjuvant treatment can be determined by considering the higher risk cancer was not confirmed in this review; rather it seems that being diagnosed with two tumors simultaneously entails a worse prognosis above and beyond that of the unilateral cancers of the same stage. To determine the true association between SBBC and breast cancer prognosis, studies of large and updated samples of SBBC should be done and include thorough histo-pathologic information.

KW - Breast Neoplasms

KW - Female

KW - Humans

KW - Neoplasms, Multiple Primary

KW - Prognosis

KW - Survival Analysis

U2 - 10.1007/s10549-014-3045-0

DO - 10.1007/s10549-014-3045-0

M3 - Review

C2 - 25007962

SN - 0167-6806

VL - 146

SP - 461

EP - 475

JO - Breast Cancer Research and Treatment

JF - Breast Cancer Research and Treatment

IS - 3

ER -