Abstract P3-12-08: Molecular Breast Cancer Subtypes in Women from Northeast China: Eight-Year Retrospective Study about Clinicopathologic Features and Survival

Background and objectives: Analysis of gene expression has identified various molecular subtypes. These molecular subtypes defined by immunohistochemistry expression of estrogen receptor (ER) or progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2) : luminal A, luminal B, basal cell-like and HER2-expresing. This study evaluates clinical and pathologic features and survival of the four molecular subtypes in premenopausal and postmenopausal women from northeast China.

Methods: A retrospective analysis of 1214 women diagnosed with breast cancer from 2000 to 2007 in Breast Surgery Department, First Hospital of Jilin University. Four molecular breast cancer subtypes defined as: luminal A (ER+ and/or PR+, HER2-), luminal B (ER+ and/or PR+, HER2+), basal-like (ER-, PR-, HER2-), and HER2-expresing, (ER-, PR-, and HER2+). We examined the prevalence of breast cancer subtypes and analyzed the associations with patient clinicopathologic features: age, menopausal status, tumor size, lymph node status, stage of cancer at diagnosis, histological characteristics, and breast cancer-specific survival.

Results: Among the all cases, the luminal A subtype was the most prevalent in our study sample (56.0%) compared with basal -like (18.5%), luminal B (13.7%), and HER2-expresing subtypes (11.8%). The four molecular subtypes differed significantly by menopausal status (P=0.011), age (P<0.001) and lymph node status (P<0.001). Luminal A subtype was more likely to with Stage II breast cancer (P<0.001) and most present with size of 2.1-5 cm (P<0.001). The luminal B and the HER2-expresing subtypes presented an increased association with more aggressive clinical course when compared with others subtypes. The estimated median follow-up period for all subjects was 54 months (range, 1 month to 120 months). The 8-year overall survival for all patients was 81.3% (95%CI, 79.4-83.7) and disease-free survival was 77.8% (95% CI, 75.4-79.9). The Kaplan-Meier curve showed breast cancer-specific survival differed significantly among the molecular subtypes (P < 0.03), with the luminal B and HER2-expresing subtypes having the poorest outcome.

Conclusion: Luminal A breast tumor appeared the better outcome than the others three subtypes and the shortest survival was HER2-expresing subtype. The poor clinical outcomes of luminal B subtype with women from northeast China were different from those of Western women could contribute to the poor prognosis of breast cancer observed in this cohort of patients and some of them couldn't accept molecular targeted therapy with trastuzumab by poor economic situations.

Figure available in online version.