Abstract P3-06-20: The correlation between body mass index (BMI) and breast cancer in both premenopausal and menopausal women in Okinawa

Abstract

Abstract Introduction Much of the longevity advantage in Okinawa is thought to be related to a healthy lifestyle including traditional foods which is low in calories and dense in nutrition. However, dietary change since World War II has been largely deleterious, with younger Okinawan people developing a higher risk of obesity and other chronic disease risk factors than older Okinawan people. In addition, breast cancer incidence and mortality are gradually increasing in Okinawa. Therefore we examined the correlation between BMI and breast cancer in both premenopausal and postmenopausal women in Okinawa. Methods The cases were 3422 female breast cancer patients without any previous breast cancer history, and the control subjects were 5622 women, who initially visited Nahanishi Clinic Okinawa in Okinawa, Japan, between May 1996 and March 2013. The median ages were 53 years old (21-99) in the breast cancer group and 44 years old (18-90) in the control group. Based on the World Health Organization classification, 25≤BMI<30 is considered as overweight and 30≤BMI as obesity. We examined the association between BMI and breast cancer risk by odds ratio. In addition, we also stratified and examined the BMI according to menstruation and age by student t test. Results Table.1 summarized the results of the association between BMI and breast cancer risk. Association between BMI and breast cancer risk. CancerControlP ValueOdds[95%CI]All patients34225622 Overweght10201028p<0.0011.89 [1.72-2.10]Obesity285253p<0.0011.93[1.62-2.30]Overweight+Obesity13051281p<0.0012.09[1.90-2.29]Premenopausal Overweight146498p = 0.0021.37[1.12-1.67]Obesity44141p = 0.0641.41[0.99-1.99]Overweight+Obesity190639p<0.0011.42[1.18-1.70]Postmenopausal Overweight618527p<0.0011.59[1.38-1.83]Obesity179112p<0.0011.96[1.54-2.51] Being overweight, or obese, increased the odds of breast cancer, as well as these put together, in the postmenopausal group (p<0.001, respectively). As for the premenopausal group, being overweight and also overweight grouped with obese increased the odds of breast cancer significantly (p = 0.002 and p<0.001, respectively) and a tendency was detected in the obese (p = 0.064). Table.2 summarized the results of BMI according to menstruation and age. BMI according to menstruation and age CancerControlp valueTotal24.3±4.122.7±3.8p<0.001Premenopausal22.9±3.922.1±3.7p<0.001Postmenopausal25.4±4.123.9±3.7p<0.001Year<3021.1±0.520.7±0.1p = 0.53930≤year<4022.5±3.921.7±3.6p<0.00140≤year<5023.2±3.822.7±3.5p<0.00150≤year<6024.6±0.123.7±6.1p<0.00160≤year<7025.5±3.924.5±3.8p<0.00170≤25.7±4.224.7±3.5p<0.001 The BMI of the breast cancer group were statistically higher than that of the control group in those over 30 years old, and in the pre and post menopausal (p<0.001, respectively). Conclusion The results of this study suggested that weight gain and consequently being overweight or obese might increase the odds for breast cancer in both premenopausal and postmenopausal women ages over 30 years old in Okinawa. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-20.