The accuracy of combined versus largest diameter in staging multifocal breast cancer

BACKGROUND: Evaluating the size of multifocal breast cancer for staging purposes is problematic. Historically, the largest tumor focus in isolation has been used to stage multifocal disease and determine optimum adjuvant therapy. This study compared multifocal and unifocal breast cancer to determine if multifocal breast cancer presents at a higher stage. STUDY DESIGN: We performed a retrospective review of a prospectively collected database of 328 patients who underwent sentinel lymph node biopsy over a 7-year period. Clinical presentation and histopathologic features of multifocal breast cancer were compared with those of unifocal disease. RESULTS: Fifty-three (16%) patients presented with multifocal disease. Higher tumor grade was observed in the multifocal tumors compared with unifocal tumors (34% versus 20% grade III tumor, multifocal versus unifocal disease; p = 0.03). Use of combined tumor focus diameter upstaged (pT status) 18 (34%) patients with multifocal tumors. There was no difference in nodal positivity based on pT status between largest and combined diameter multifocal disease. CONCLUSIONS: Combined tumor diameter in multifocal breast cancer does not correspond with an increase in sentinel node positivity and should not be used for staging purposes.