Abstract P3-13-05: Estrogen Receptor-Positive Breast Cancer in Japanese Women: Trends in Incidence, Characteristics and Prognosis

Abstract

Abstract Background: The incidence of breast cancer in Japanese women has doubled in all age groups over the past two decades. Patients and Methods: We examined the characteristics of patients and tumors treated in three time periods between 1982 and 2010. Estrogen receptor (ER), progesterone receptor (PgR), and HER2 status were assessed by immunohistochemistry. Correlation of hormone receptor levels with clinicopathological factors and prognosis was analyzed in ER-positive, HER2-negative breast cancer in two age groups (≥50 years vs. >50 years). Results: A total of 1903 women with breast cancer, who were treated at Nagoya City University Hospital, were included in this study. The frequency of ER-positive breast cancer in women aged 50 years or younger increased greatly over the interval studied (1982-1991: 52.5%, 1992-2001: 72.6%, 2002-2010: 87.1%, P < 0.0001). The frequency of ER-positive tumors was also significantly increased in women over 50 years of age (1982-1991: 69.4%, 1992-2001: 73.3%, 2002-2010: 78.6%, P = 0.029). In ER-positive, HER2-negative breast cancer, tumor grade was negatively correlated with expression levels of ER (P = 0.0029) and PgR (P < 0.0001). Interestingly, PgR levels were significantly higher in women aged 50 years or younger than in women over 50 years old (P < 0.0001). In both age groups, the prognosis for patients with ER-positive, HER2- negative breast cancer significantly improved over time, due to advances in adjuvant therapies. ER and PgR expression levels were not associated with disease-free survival. Lymph node status and tumor size were strong prognostic factors regardless of the biological characteristics of the tumors in ER-positive, HER2-negative breast cancer in both age groups. Conclusions: It is necessary to establish risk factors, both genetic and environmental, capable of predicting the risk of ER-positive breast cancer and thus enable the efficient selection of candidates for hormone receptor-targeted chemoprevention. Furthermore, new approach should be considered to improve survival for node-positive, ER-positive breast cancer. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-13-05.