The Effect of Total Size of Lesions in Multifocal/Multicentric Breast Cancer on Survival

Background In this study, we aimed to assess the prognostic performance of determining the T stage according to the total size of lesions compared with the size of the largest lesion in the breast in patients with multifocal/multicentric (MF/MC) breast cancer. Patients and Methods The charts of the patients with MF/MC breast cancer who were diagnosed between 2003 and 2014 were reviewed. The T stage of MF/MC tumors was determined according to the largest lesion size (Tmax) as well as the sum of the longest diameters of the lesions (Tsum) in the breast. Results Multifocal/multicentric tumors were identified in 323 of 3890 patients (8.3%) with breast cancer. Ten-year rates of overall survival (OS; 75% and 74%; P = .965) and disease-free survival (DFS; 66% and 61%; P = .817) were similar in patients with unifocal and MF/MC tumors, respectively. When the T stage was determined by summing the sizes of the lesions, the T stage of 67 (20.7%) and 63 (19.5%) patients advanced from T1 to T2 and from T2 to T3, respectively. Thus, the T stage increased in 130 patients (40.2%) according to American Joint Committee on Cancer. Discriminatory ability of Tsum was better than Tmax in terms of OS and DFS, as shown with higher Royston D and Harrel C statistics and Schemper V values. Conclusion The new T classification proposed in this report stands out as a better predictive classification particularly in patients with low disease burden.