Comparing the outcome between multifocal, multicentric, and bilateral breast cancer and the impact of guideline-adherent adjuvant treatment: A retrospective multicenter cohort study of 5,308 patients.

Abstract

1078 Background: Beside unifocal-unilateral (UU) breast cancer (BC) there are several subtypes including multifocal, multicentric and bilateral BC. This study tries to answer the following questions:(1) Does localization (multifocal/multicentric/bilateral) influence outcome concerning BC mortality? (2) Is there an impact of guideline-adherent adjuvant treatment in these BC subtypes? Methods: This German multi-center retrospective cohort study called BRENDA included 5277 patients obtained from 1992 until 2005. The definition of guideline adherence was based on the German national S3 breast cancer guideline (2004). Results: 4085 (77.4%) were UU, 698 (13.2%) multifocal, 282 (5.3%) multicentric and 212 (4.0%) bilateral BC. RFS in multifocal [p=0.003; HR=1.35 (95% CI: 1.11-1.65)], multicentric [p<0.001; HR=1.76 (95% CI: 1.31-2.34)] and bilateral [p<0.001; HR=2.28 (95% CI: 1.76-2.97)] BC was significantly lower compared to unilateral-unifocal BC. Concerning OAS we found only a borderline difference between UU and unilateral-multifocal [p=0.057; HR=1.22 (95% CI: 0.99-1.48)], but a significant difference between multicentric [p= 0.018; HR=1.42 (95% CI: 1.06-1.90)] resp. bilateral [p<0.001; HR=2.87 (95% CI: 2.21-3.74)] and UU-BC. There was a significant impact by guideline adherent adjuvant therapy [UU: p<0.001, HR=2.76,95%C.I.:2.25-3.38], [unilateral-multifocal: p=0.001, HR=2.04,95%C.I.:1.33-3.14], [unilateral-multicentric: p=0.020, HR=2.13,95%C.I.:1.13-4.01] and [bilateral: p=0.042, HR=2.10,95%C.I.:1.03-4.31]. After stratifying for 100% guideline adherent treatment and adjusting for age, tumor size, nodal status and grading there was no significant difference in RFS/OAS in patients with multifocal [p=0.282/p=0.610], multicentric [p=0.829/p=0.609] or bilateral BC [p=0.457/p=0.773] compared to patients with UU-BC. Conclusions: Patients with multicentric and bilateral BC have primarily a worse prognosis in terms of RFS and OAS. However if guideline adherent adjuvant treatment was applied it was no more possible to demonstrate significant differences in survival.