Zhou et al. BMC Cancer 2010, 10:653 http://www.biomedcentral.com/1471-2407/10/653 R E S E A R C H A R T I C L E Open Access Long-term survival of women with basal-like ductal carcinoma in situ of the breast: a population-based cohort study Wenjing Zhou1*, Karin Jirström2, Christine Johansson3, Rose-Marie Amini3, Carl Blomqvist4, Olorunsola Agbaje5, Fredrik Wärnberg1 Abstract Background: Microarray gene-profiling of invasive breast cancer has identified different subtypes including luminal A, luminal B, HER2-overexpressing and basal-like groups. Basal-like invasive breast cancer is associated with a worse prognosis. However, the prognosis of basal-like ductal carcinoma in situ (DCIS) is still unknown. Our aim was to study the prognosis of basal-like DCIS in a large population-based cohort. Methods: All 458 women with a primary DCIS diagnosed between 1986 and 2004, in Uppland and Västmanland, Sweden were included. TMA blocks were constructed. To classify the DCIS tumors, we used immunohistochemical (IHC) markers (estrogen-, progesterone-, HER2, cytokeratin 5/6 and epidermal growth factor receptor) as a surrogate for the gene expression profiling. The association with prognosis was examined for basal-like DCIS and other subtypes using Kaplan-Meier survival analyses and Cox proportional hazards regression models. Results: IHC data were complete for 392 women. Thirty-two were basal-like (8.2%), 351 were luminal or HER2- positive (89.5%) and 9 unclassified (2.3%). Seventy-six women had a local recurrence of which 34 were invasive. Another 3 women had general metastases as first event. Basal-like DCIS showed a higher risk of local recurrence and invasive recurrence 1.8 (Confidence interval (CI) 95%, 0.8-4.2) and 1.9 (0.7-5.1), respectively. However, the difference was not statistically significant. Also, no statistically significant increased risk was seen for triple-negative or high grade DCIS. Conclusions: Basal-like DCIS showed about a doubled, however not statistically significant risk for local recurrence and developing invasive cancer compared with the other molecular subtypes. Molecular subtyping was a better prognostic parameter than histopathological grade. Background Increased use of screening mammography, beginning in the early 1980 s, has resulted in a dramatic increase in detection of ductal carcinoma in situ (DCIS). DCIS is a pre-invasive disease with a clinically and molecularly heterogeneous presentation that poses a major challenge in both diagnosis and treatment [1-3]. A clinically accepted classification system predicting prognosis is still missing. * Correspondence: wenjing.zhou@surgsci.uu.se 1Department of Surgical Science, Uppsala University, Uppsala, SE-75105, Sweden Full list of author information is available at the end of the article Recently, the idea of using molecular subtyping to pre- dict the prognosis of invasive breast cancer has been widely accepted [4-8]. The introduction of high- throughput DNA microarray technologies marked an entirely new era of genome-wide approaches to predict prognosis and outcome [9,10]. According to similarities in gene expression characteristics, Perou et al., [11] crea- tively classified breast cancer into five subtypes: luminal A, luminal B, basal like, HER2-positive and normal-like. Molecular subtypes have been shown to have prognostic and treatment predictive value. Among those, the basal- like tumors are characterized as expressing genes related to myoepithelial cells [12]. Follow-up studies have shown that basal-like cancer is associated with a higher © 2010 Zhou et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.