Zhou et al. BMC Cancer 2010, 10:653 http://www.biomedcentral.com/1471-2407/10/653 Table 2 Cox regression analyses by molecular subgroup, by immunohistochemistry Page 5 of 8 All (n = 392) Univariate HR (95% CI) Adjusted* HR (95% CI) Breast Conserving Surgery (n = 298) Univariate HR (95% CI) Adjusted* HR (95% CI) Event: local recurrence (n = 76) Gene-expression classification Non basal-like (n = 360) Basal-like (n = 32) Triple-negative classification Non triple-negative (n = 377) Triple-negative (n = 32) Tumor grade I (n = 30) II (n = 182) III (n = 176) Postoperation radiotherapy No (n = 252) Yes (n = 140) Gene-expression classification Non basal-like (n = 360) Basal-like (n = 32) Triple-negative classification Non triple-negative (n = 377) Triple-negative (n = 32) Tumor grade I (n = 30) II (n = 182) III (n = 176) Postoperation radiotherapy No (n = 252) Yes (n = 140) 1 (Reference) 1.7 (0.8-3.8) 1 (Reference) 1.1 (0.4-2.7) 1 (Reference) 1.2 (0.4-3.4) 1.0 (0.3-2.9) 1 (Reference) 0.9 (0.5-1.5) 1 (Reference) 2.0 (0.8-5.0) 1 (Reference) 1.4 (0.5-4.0) 1 (Reference) 1.0 (0.3-3.3) 0.7 (0.2-2.4) 1 (Reference) 0.8 (0.4-1.6) 1 1.9 (0.8-4.2) 1 1.1 (0.4-2.9) 1 1.4 (0.5-4.0) 1.3 (0.5-3.9) 1 0.7 (0.4-1.3) 1 1.9 (0.7-5.1) 1 1.6 (0.6-4.8) 1 1.1 (0.3-3.8) 1.1 (0.3-3.9) 1 0.7 (0.3-1.5) 1 1.6 (0.7-3.6) 1 1.0 (0.4-2.7) 1 1.3 (0.5-3.9) 1.4 (0.5-4.0) 1 0.8 (0.4-1.4) 1 2.2 (0.8-5.6) 1 1.7 (0.6-4.9) 1 1.1 (0.3-3.8) 0.9 (0.2-3.1) 1 0.7 (0.3-1.4) Event: invasive- and general recurrence (n = 47) 1 1.8 (0.7-4.2) 1 1.0 (0.3-2.9) 1 1.4 (0.5-3.9) 1.4 (0.5-4.2) 1 0.7 (0.4-1.4) 1 2.3 (0.8-6.1) 1 2.1 (0.7-6.3) 1 1.1 (0.3-3.8) 1.0 (0.3-3.9) 1 0.7 (0.3-1.6) where SISH failed. SISH results are more reliable [31,32] especially for the borderline cases scored as 2+ by IHC. By using both methods we should have minimized the risk of subtype misclassification. Our results indicated that the molecular subtypes of DCIS were not related to basic characteristics as histo- pathological grade and tumor size. However, many potential prognostic factors may interact with the choice of adjuvant therapy [29] and we therefore adjusted for adjuvant treatment and type of surgery in the analyses. In this study, no women received chemotherapy or anti- estrogen. One hundred and forty received postoperative radiotherapy. The percentage of patients who received postoperative radiotherapy was fairly evenly distributed among the groups with different subtype of DCIS. The type of surgery was also evenly distributed. Basal-like invasive breast cancer is an entity that is lar- gely characterized by positive expression of basal CKs and other genes that are characteristic of basal-like cells and by high proliferative activity. Basal-like invasive breast cancer is considered to be associated with poor prognosis [13] and this supposition has been proved in many studies [4,5,13,17,33,34]. In our study, we found about a doubled risk for local recurrence and invasive- or general recurrences for basal-like DCIS. The higher risk was not statistically significant but, on the other hand, it was consistent in the univariate, multivariate and Kaplan-Meier analyses for all patients and for the subgroup of patients with BCS. Although we have con- ducted a population-based study with long follow-up, we were not able to show a statistically significantly poorer prognosis for the basal-like DCIS. Like in inva- sive breast cancer, the basal-like subgroup is small and this makes the statistical power low and a conclusive study would have to include a much larger number of patients. Today, we take nuclear grade, size, necrosis and margins into consideration when designing adjuvant treatment after BCS of DCIS according to the Swedish