Abstract P4-10-15: Obesity influences the character of the breast cancer in postmenopausal women in Japan

Abstract

Abstract Background: We know Estrogen Receptor (ER) positive and/or Progesterone Receptor (PgR) positive tumors tend to develop more frequently in obese individuals in postmenopausal women. However, the average body size of a Japanese woman is relatively smaller than that of a Caucasian woman. There are few reports about the influence of the obesity to the character of the Japanese breast cancer women and the tendency is not clear. The aim of this study is to clarify whether the tendency is the same even in Japanese breast cancer women. Furthermore, we investigate whether HER2 expression (HER2) and Ki-67 index (Ki-67) have some relations with the height (HT), the weight (WT) and the body mass index (BMI) in Japanese breast cancer women. Methods: HT and WT of 279 Japanese women with breast cancer in Kitamurayama hospital were evaluated. The mean HT and WT of them are 153.6cm and 54.9kg. Subsequently, the women's BMI (WT/(HT)2) was calculated. The mean BMI was 23.3. The ER and PgR were stained for immunohistochemical (IHC) analysis. Regardless of the intensity, stained cases were defined as positive. HER2 was divided into HER2 negative (IHC score 0, +1 and/or FISH negative) or positive (IHC score +3 and/or FISH positive). Ki-67 was determined by staining with MIB-1 antibody, and the cutoff value was decided on 20%, and divided into two groups of more than 20% (Higher) and less than 20% (Lower). Then, we examined the relationship of HT, WT and BMI with ER, PgR, HER2 and Ki-67 in postmenopausal and premenopausal women. Result: In postmenopausal women, WT and BMI were significantly higher in ER positive (p=0.0230, p=0.0129). WT and BMI were also significantly higher in PgR positive (p=0.0049, p=0.0294,). There was no significant difference between HER2 positive and Her2 negative, and between Ki-67 Higher and Ki-67 Lower either. In premenopausal women, no significant association was observed in all items. Conclusion: In postmenopausal women, HT did not have the significant difference between ER (and PgR) positive and ER (and PgR) negative. However, ER (and PgR) positive were significantly higher in WT and BMI. It was thought that the obesity influences the character of the breast cancer in postmenopausal women. Compared to less obese postmenopausal Japanese women with breast cancer, more obese postmenopausal Japanese women have a propensity for developing hormone sensitive tumors. Citation Format: Suzuki M, Takei H. Obesity influences the character of the breast cancer in postmenopausal women in Japan [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-10-15.