Body mass index and breast cancer defined by biological receptor status in pre-menopausal and post-menopausal women: a multicenter study in China.
BACKGROUND
Few studies have investigated the association between body mass index (BMI) and breast cancer with consideration to estrogen/progesterone/human epidermal growth factor type 2 receptor status (ER/PR/HER2) in the breast tissue among Chinese pre- and post-menopausal women.


METHODS
Four thousand two hundred and eleven breast cancer patients were selected randomly from seven geographic regions of China from 1999 to 2008. Demographic data, risk factors, pathologic features, and biological receptor status of cases were collected from the medical charts. Chi-square test, fisher exact test, rank-correlation analysis, and multivariate logistic regression model were adopted to explore whether BMI differed according to biological receptor status in pre- and post-menopausal women.


RESULTS
Three thousand two hundred and eighty one eligible cases with BMI data were included. No statistically significant differences in demographic characteristics were found between the cases with BMI data and those without. In the rank-correlation analysis, the rates of PR+ and HER2+ were positively correlated with increasing BMI among post-menopausal women (rs BMI, PR+=0.867, P=0.001; rs BMI, HER2+ =0.636, P=0.048), but the ER+ rates did not vary by increasing BMI. Controlling for confounding factors, multivariate logistic regression models with BMI<24 kg/m(2) as the reference group were performed and found that BMI ≥ 24 kg/m(2) was only positively correlated with PR+ status among post-menopausal breast cancer cases (adjusted OR=1.420, 95% CI: 1.116-1.808, Wald=8.116, P=0.004).


CONCLUSIONS
Post-menopausal women with high BMI (≥ 24 kg/m(2)) have a higher proportion of PR+ breast cancer. In addition to effects mediated via the estrogen metabolism pathway, high BMI might increase the risk of breast cancer by other routes, which should be examined further in future etiological mechanism studies.
Department of Environmental Health and Occupational Medicine, West China School of Public Health & No.4 West China Teaching Hospital, Sichuan University, Chengdu, China ; Department of Cancer Epidemiology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Jing
J
Li
Department of Epidemiology and Biostatistics, West China School of Public Health & No.4 West China Teaching Hospital, Sichuan University, Chengdu, China.
Yuan
Y
Huang
Center of Breast Disease, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Bao-Ning
BN
Zhang
Department of Cancer Epidemiology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Jin-Hu
JH
Fan
Department of Epidemiology and Biostatistics, West China School of Public Health & No.4 West China Teaching Hospital, Sichuan University, Chengdu, China ; Department of Cancer Epidemiology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Rong
R
Huang
Department of Medical Oncology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Pin
P
Zhang
Department of Radiation Oncology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Shu-Lian
SL
Wang
Department of Pathology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Shan
S
Zheng
Department of Breast Surgery, Liaoning Cancer Hospital, Shenyang, China.
Bin
B
Zhang
Department of Breast Surgery, Zhejiang Cancer Hospital, Hangzhou, China.
Hong-Jian
HJ
Yang
Department of Breast Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China.
Xiao-Ming
XM
Xie
Department of Breast-thyroid Surgery, Xiangya Second Hospital, Central South University, Changsha, China.
Zhong-Hua
ZH
Tang
Department of Breast Surgery, the Second People's Hospital of Sichuan Province, Chengdu, China.
Hui
H
Li
Department of Oncosurgery, the First Affiliated Hospital of Medical College, Xi'an JiaoTong University, Xi'an, China.
Jian-Jun
JJ
He
Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, United States of America.
Evelyn
E
Hsieh
Department of Cancer Epidemiology, Cancer Institute & Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
You-Lin
YL
Qiao
Department of Epidemiology and Biostatistics, West China School of Public Health & No.4 West China Teaching Hospital, Sichuan University, Chengdu, China.
Jia-Yuan
JY
Li
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002681:China; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D017697:Premenopause; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D012189:Retrospective Studies; D012307:Risk Factors
D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human