Variable T stage Age Grade¶ ERa PRb HR HER2c HR/HER2 HR/HER2 p53d Ki-67d T1mic T1a T1b ≤ 35 >35 1 (low) 2 3 (high) negative positive negative positive ER-PR- ER+ and/or PR+ Negative Positive HR+HER2- HR+HER2+ HR-HER2+ HR-HER2- HR+ and/or HER2+ HR-HER2- <10%; ≥10% <10% ≥10% 120 93 162 23 352 28 152 71 136 237 187 186 122 251 276 96 220 31 65 56 316 56 220 143 275 88 4 2 6 3 9 1 5 2 7 5 9 3 7 5 8 3 4 1 2 4 7 4 4 6 6 4 97.4 97.8 96.9 90.9 97.7 96.3 96.6 98.6 95.1 98.2 96.0 98.2 94.9 98.4 97.4 97.9 98.6 96.8 98.5 92.6 98.4 92.6 97.9 97.1 98.4 95.5 Kwon et al. BMC Cancer 2010, 10:557 http://www.biomedcentral.com/1471-2407/10/557 Table 2 Number of events and five year recurrence free survival according to prognostic factors No. of patients No. of events Proportion surviving to 5 years (%) ¶ Only T1a, T1b patients were analyzed using nuclear/histolgogic grade. a,bData of hormone receptor status was available in 373 patients. ;<10%;negative, ≥10%;positive. c HER2 status was determined by immunohistochemistry and was available in 372 patients.; 0,1+,2+;negative, 3+;positive. dData of p53 and i-67 was available in 363 patients. chemotherapy of cyclophosphamide, methotrexate, fluorouracil. No patients received adjuvant trastuzumab. T1mic patients were more likely to be candidates for observation without any systemic adjuvant therapy (75.8% in T1mic group, 53.6% in T1a, and 38.7% in T1b, P < 0.0001). Recurrence and prognosis Median follow up duration for all patients was 60.8 months while median RFS duration was not reached as of the time of this writing. The five-year cumulative RFS rate was 97.2%, and recurrent disease was diagnosed in 12 patients during this follow up period. There was no difference in five-year RFS between T1mic, T1a and T1b patients (97.4% for T1mic, 97.8% for T1a, and 96.9% for T1b, p = 0.681) (Table 2). The rate of local or regional recurrence did not show a statistically signifi- cant difference between patients who received or not received adjuvant radiotherapy among the patients who received breast conserving surgery (p = 0.871). Page 4 of 8 p value 0.681 0.002 0.696 0.123 0.126 0.069 0.772 0.225 0.018 0.543 0.148