Does Tumor Size in T1-T2 Early Breast Cancer (EBC) Still Have a Prognostic Role?

e12087 Background: Theprognosis of EBC patients (pts) depends on pts characteristics and tumor biological/ histopathological features. The correlation between tumor size, expressed as the largest diameter in TNM staging, and overall survival (OS) and disease free survival (DFS) is well recognized. According to TNM, tumors classified as T2, could have different volumes (V); e.g. a tumor of 2,1 cm has a V of 4500 mm3, while a tumor of 4,9 cm has a V of 60000 mm3. Despite belonging to the same class, the two different V may have a different prognosis. The aim of the study is to establish if the role of tumor size has been surpassed by other factors. Methods: The purpose is to evaluate the correlation between V and DFS/OS, in a T1-T2 population, who underwent breast surgery and sentinel lymph node biopsy, in our institution from 01.01.2005 to 30.09.2013. V was evaluated with the measurement of three half-diameters of the tumor (a, b and c), and calculated with this formula: 4/3 * π * a * b * c. Results: 341 pts with T1-T2 EBC who underwent surgery were included. 86,5% were treated with conservative surgery. 85,1% had a luminal subtype, 9,1% triple negative (TN) and 7,4% Her2 positive (+). Median V was 942 mm3 (range 0,52-31651,2). 44 pts (12,9%) relapsed and 23 pts died. With a median follow-up of 6,5 years, the univariate analysis for DFS showed a correlation between age (p 0,016), tumor size (p 0,032), V (p 0,078), histological grading (p 0,001), molecular subtype (p < 0,001). The multivariate analysis confirmed the statistically significant correlation only for molecular subtype (p 0,005), showing a worse prognosis for TN and Her2+ subtypes. Regarding OS, a statistically significant correlation was shown by the univariate analysis both for histological grading (p 0,018) and molecular subtype (p 0,001). The multivariate analysis confirmed that TN and Her2+ subtypes negatively influence OS (p 0,005). Conclusions: In our study neither V nor tumor diameter seem to correlate with DFS and OS in T1-T2 tumors; the only parameter that strongly influences DFS and OS, is molecular subtype, confirming the worse prognosis of TN and Her2+ versus luminal tumors. These findings encourage clinics to choose adjuvant treatment not based on dimensional criteria but on biological features.