Abstract P6-09-09: Body mass index and prognosis after breast cancer diagnosis in Japanese women

Abstract

Abstract Background: Studies conducted mainly in Western countries have reported a relationship between body mass index (BMI) and prognosis among women with breast cancer. Only a few studies have been conducted in Japan so far because the percentage of high BMI is low. In the present retrospective study, we investigated the associations between BMI and the clinical characteristics and prognosis among breast cancer patients. Methods: We analyzed 1,744 breast cancer patients who started treatment between 2004 and 2012 at a single hospital in Japan. All patients with ductal carcinoma in situ, male breast cancer as well as metachronous and synchronous bilateral breast cancer were excluded. Median age was 57 years (range 23–91). The number of patients less than 50 years old was 496. World Health Organization BMI classifications were used: Underweight, less than18.5 kg/m2, n=157; Normal, 18.5–24.9 kg/m2, n=1181; Overweight, 25–29.9 kg/m2, n=316; and Obese, more than or equal to 30kg/m2, n=90. The Cox proportional hazards model was used to estimate hazard ratios for recurrence free survival (RFS) in relation to BMI classifications. Results: Median follow up interval was 4.2 years. During the follow-up period, 126 breast cancer recurrences were observed. BMI classification correlated with clinical tumor size (cT) significantly and BMI classification tended to correlate with lymph node metastases and estrogen receptor (ER) status. Among patients less than 50 years old, the RFS of those with BMI ≥25.0 kg/m2 was compared to that of patients with BMI <25.0 kg/m2. In multivariate analyses, BMI classification was one of the significant factors (p=0.02) along with lymph node metastases (p=0.0001) and ER status (p=0.04). However in patients aged 50 years or over BMI category was not a significant factor (p=0.12). Conclusions: It has been reported that higher BMI is a risk factor for breast cancer recurrence among postmenopausal patients. Our results suggest that higher BMI is also associated with an increased risk of breast cancer recurrence among premenopausal patients. It raises the possibility that maintaining an appropriate body weight improves the prognosis in premenopausal patients after they have been diagnosed. Citation Format: Toshinari Yamashita, Tomoyuki Aruga, Hiromi Miyamoto, Kazumi Horiguchi, Yayoi Honda, Nami Idera, Risa Goto, Katsumasa Kuroi. Body mass index and prognosis after breast cancer diagnosis in Japanese women [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-09-09.