Kwon et al. BMC Cancer 2010, 10:557 http://www.biomedcentral.com/1471-2407/10/557 Table 4 Clinicopathologic features of patients with recurrence Systemic adjuvant treatment None None None None None Hormone therapy Chemotherapy Chemotherapy None Chemotherapy Hormone therapy None No. 1 2 3 4 5 6 7 8 9 10 11 12 Age at diagnosis 31 36 50 35 62 29 52 38 52 53 38 60 T stage T1mic T1mic T1mic T1mic T1a T1a T1b T1b T1b T1b T1b T1b Loco-regional Treatment BCS BCS, RTx BCS, RTx Mastectomy BCS, RTx Mastectomy BCS BCS, RTx Mastectomy BCS, RTx Mastectomy Mastectomy Abbreviation: BCS, breast conserving surgery; RTx, radiotherapy. HER2-positive disease is a risk factor of recurrence in node-negative tumors 1cm or smaller [25]. However, most studies on the prognosis of node-negative early breast cancer were performed in Western countries. In contrast, few studies exist regarding the biology and prognosis of Asian breast cancer patients. In the present study, triple negative status and age younger than 35 were the only independent prognostic factors of recurrence. Other studies have reported simi- lar results in which younger patients showed poorer prognosis than older patients. These authors suggested that poor prognosis observed in young patients under the age of 35 was related to adverse characteristics of their disease, such as a high proportion of node-positive disease, a high proportion of negative estrogen hormone receptor, and a high proliferation index. However, age younger than 35 years remained an independent poor prognostic factor in the multivariate analysis. However, an analysis of the prognosis of a specific subgroup with tumor sizes of 1 cm or less was not performed in this study [9]. In our patients, there were no differences in pathologic characteristics of hormone receptor status or HER2 status according to age group (Table 5). Our data suggest that age younger than 35 is an independent risk factor for recurrence, even in patients with node- negative breast cancer 1 cm or less in size. Therefore, young age less than 35 should be regarded as a poor prognostic factor when adjuvant therapy is considered. This is important, especially for Asian patients, because the proportion of young women in Asian countries is higher than in Western countries [5,26]. The grade of HER2 overexpression which was a poor prognostic factor in other studies [24,25,27,28] did not have an effect on RFS in our study. This discrepancy can be attributed to the fact that HER2 fluorescence in situ hybridization (FISH) was not performed in most ER PR HER2 Site of recurrent disease RFS (months) + + - Remnant breast + - + Remnant breast - - - Remnant breast - - + Lung - - Unknown Remnant breast + + - Chest wall - - - Remnant breast - - + Lung, Skin - - - Lung - - - Remnant breast + + - Remnant breast + - - Remnant breast Page 6 of 8 37.5 21.1 20.2 69.9 31.6 30.3 39.9 29.5 6.1 27 26.6 121.2 of the patients. There is a possibility that HER2 FISH positive disease was classified as HER2 negative based on immunohistochemical staining only. A literature show that quite a few patients with moderate expression (+2) of HER2 in immunohistochemistry had HER2 gene amplification at FISH [29]. Another explanation for the lack of an association between HER2 status and recur- rence may be the inclusion of T1mic disease in the ana- lysis. Patients with T1mic disease have a higher proportion of HER2 positive disease but a very low potential of systemic metastasis or recurrence. In our series, endocrine unresponsiveness and positive HER2 immunohistochemical staining (+3) were more common in T1mic tumor than T1a or T1b disease. The reason for high HER2 positive rate in T1mic tumor is not Table 5 Pathologic characteristics according to age group Age ≤ 35 (%) Age > 35 (%) P value Hormone receptor (HR) ER+ and/or PR+ ER-PR- HER2a Negative Positive HR/HER2 HR+ and/or HER2+ HR-HER2- p53 Ki-67 <10%; ≥10% <10% ≥10% 14 (60.9) 9 (39.1) 8 (34.8) 15 (65.2) 19 (82.6) 4 (17.4) 13 (59.1) 9 (40.9) 15 (68.2) 7 (31.8) 237 (67.7) 113 (32.3) 88 (25.2) 261 (74.8) 297 (85.1) 52 (14.9) 207 (60.7) 134 (39.3) 260 (76.2) 81 (23.8) 0.498 0.328 0.763 1.000 0.441 aHER2 status was determined by immunohistochemistry and was available in 372 patients.; 0,1+,2+;negative, 3+;positive.