Abstract 893: Obesity, weight change, and survival of breast cancer in premenopausal and postmenopausal women Korea
Authors: Oh Hyun-Kyung , Nam Seok-Jin , Yang Jung-Hyun , Shin Myung-Hee 
Published: February 2011

Large body of evidence suggests that obesity is associated with poor survival of breast cancer. However, this association is not entirely consistent among younger or premenopausal women. We investigated the association of obesity and the survival from pre- and postmenopausal breast cancer in Korea. Breast cancer patients in this study were women who previously participated in a hospital-based case-control study. A total of 1,357 patients (937 premenopausal and 420 postmenopausal women) who were first diagnosed between 1998 and 2004 and aged between 35 and 70 were included in the study. Patients were interviewed at the time of diagnosis on the risk factors of breast cancer including current body weight, weight at 2 years prior to diagnosis, weight at age 18, and adult height. Clinical records and pathologic reports were retrieved and the information on tumor characteristics, such as TNM, stage, estrogen receptor (ER), progesterone receptor (PR), and C-erbB-2, and type of treatment were coded. Patients were followed up until Dec. 31, 2007. Deaths were confirmed through hospital cancer registry and the National Death Certificate Database. Hazard ratios (HR) were calculated using Cox's proportional hazard model.

We observed 111 deaths from all cause and 74 deaths from breast cancer. Five-year survival rate for breast cancer was 94.4% for premenopausal patients and 96.2% for postmenopausal patients. Obesity was not associated with breast cancer mortality in premenopausal patients. Compared to women with Body Mass Index (BMI) at diagnosis &lt; 25kg/m2, women with BMI &gt;= 25kg/m2 had 0.7 times risk of death from breast cancer (95% Confidence Interval (CI) = 0.3-1.4). However, obesity was positively associated with breast cancer mortality in postmenopausal patients. Compared to women with BMI at diagnosis &lt; 25kg/m2, women with BMI &gt;= 25kg/m2 had 3.1 times higher risk of death from breast cancer (95% CI = 1.1-8.7). Weight loss during the two years prior to diagnosis was associated with breast cancer mortality in premenopausal patients. Compared to women whose weight changed less than 5 % during the 2 years prior to diagnosis, women who lost more than 5% of their weight had 2.9 times higher risk of death from breast cancer (95% CI = 1.4-6.1). Women who gained more than 5% of their weight did not have increased risk of death from breast cancer (HR = 1.2, 95% CI = 0.6-2.2). There was no association between weight change and breast cancer mortality in postmenopausal patients (HR for weight loss group = 0.9, 95% CI = 0.2-3.8, HR for weight gain group = 0.9, 95% CI = 0.2-4.0).

In conclusion, obesity was associated with poorer survival of breast cancer in postmenopausal women but not in premenopausal women.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 893.