STEROID ENZYMES AND CANCER Application of a New Classification to a Breast Tumor Series from a Population-Based Cancer Registry Demographic, Clinical, and Prognostic Features of Incident Cases, Palermo Province, 2002–2004 Maurizio Zarcone, a Rosalba Amodio, b Ildegarda Campisi, a Rosanna Cusimano, b,c Cecilia Dolcemascolo, a Vitale Miceli, a Adele Traina, a and Maurizio Macaluso d a Palermo Breast Cancer Registry and Experimental Oncology Unit, Department of Oncology, ARNAS-Civico, Palermo, Italy b Palermo Province Cancer Registry, Department of Hygiene, University of Palermo, Italy c Department of Epidemiology of ASL6, Palermo, Italy d Residency Program in Hygiene and Preventive Medicine, Department of Hygiene, University of Palermo, Italy A new classification based on gene expression profiling or immunohistochemical (IHC) characteristics may replace current histopathological classifications and predict bet- ter clinical outcomes. We used IHC markers to classify incident cases ascertained by the Palermo Breast Cancer Registry (2002–2004) into four subtypes: luminal-A (ER+ or PgR+ and HER2/neu−); luminal-B (ER+ or PgR+, HER2/neu+); basal-like (ER−, PgR−, HER2/neu−); and HER2+/ER− (HER2/neu+, ER−, PgR−). We evaluated HER2/neu, ER and PgR in 1300/1985 (65%) cases. The most common IHC-subtype was luminal-A (68%), whereas luminal-B, basal-like, and HER2+/ER− accounted for 14%, 13%, and 5%, respec- tively. IHC-subtypes were not associated with tumor size, geographic location within the province, or menopause, but differed by NPI (P < 0.0001), grading (P < 0.0001), lymph-node involvement (P = 0.04), metastases (P = 0.04), and TNM stage (P = 0.04). Endocrine therapy was administered to 81% of 519 postmenopausal, luminal-A, and luminal-B cases and to 32% of 114 postmenopausal, basal-like, and HER2+/ER− cases. Key words: breast cancer; luminal classification; basal-like; endocrine treatment, im- munohistochemical (IHC) characteristics Introduction Breast cancer is a heterogeneous malignancy comprising categories with distinct molecular characteristics often correlated with clinical outcome. This disease has become a model for the development of therapies that target tumor- Address for correspondence: Adele Traina, M.D., Experimental On- cology Unit, Department of Oncology, M. Ascoli, ARNAS-Civico, Via Carmelo Lazzaro 2, 90127 Palermo, Italy. Voice: +39 091 666 4345 or 4347; fax: +39 091 666 4352. registrotumori@ospedalecivicopa.org specific biologic pathways used by cancer cells to escape homeostatic control of growth and differentiation. As the employment of targeted therapy in- creases, it becomes more important to classify cases according to the particular biomarker profiles for which specific treatment proto- cols are available. 1–3 Breast cancer classifica- tion based on gene expression profiling or im- munohistochemical (IHC) characteristics may soon replace the traditional histopathological classification because it may provide a more Steroid Enzymes and Cancer: Ann. N.Y. Acad. Sci. 1155: 222–226 (2009). doi: 10.1111/j.1749-6632.2008.03693.x C  2009 New York Academy of Sciences. 222