Objective:To investigate the risk factors for breast cancer in Luzhou

China through a case-control study

and to provide a basis for developing prevention strategies for breast cancer.Methods:A case-control study matched at a ratio of 1:1 was performed.The patients with breast cancer who were diagnosed for the first time in The Affiliated Hospital of Southwest Medical University were enrolled as case group

and with an age of ±3 years and place of residence as matching conditions

the neighbors without breast cancer who lived in the same village or subdistrict as the breast cancer patients were enrolled as control group.A stratified analysis based on place of residence and menopause was performed to investigate the risk factors for breast cancer in urban or rural areas and before or after menopause.Results:The univariate analysis showed that there were significant differences between the case group and the control group in age of menarche

intake of coarse grains

intake of beans

and emotional state（depression and irritability）（P

<

0.05）.The multivariate analysis showed that late age of menarche（odds ratio [OR]=0.815

95% confidence interval [CI]

:0.722～0.919）

high number of childbirths（OR=0.777

95% CI:0.615～0.983）

intake of beans（OR=0.267

95% CI:0.137～0.524）

and intake of coarse grains（OR=0.272

95% CI:0.132～0.56） were protective factors against breast cancer

while depression for more than two consecutive weeks in the past year（OR=3.339

95% CI:1.675～6.659） and depression for most of the times in more than two years（OR=2.3

95% CI:1.047～5.055） were risk factors for breast cancer.The multivariate stratified analysis for urban and rural areas showed that getting irritable for more than two consecutive weeks in the past year(OR

rural

=1.769

95% CI:1.058～2.957;OR

urban

=9.168

95% CI:3.291～25.539) was a common risk factor for breast cancer in both rural and urban areas.For women in the urban area

number of abortions（OR=1.477

95% CI:1.123～1.941） was a risk factor

while intake of fresh fruits（OR=0.124

95% CI:0.025～0.624） was a protective factor against breast cancer.For women in the rural area

late age of menarche（OR=0.83

95% CI:0.729～0.945）

intake of beans（OR=0.115

95% CI:0.048～0.277）

and intake of coarse grains（OR=0.114

95% CI:0.039～0.337） were protective factors against breast cancer

and depression for more than two consecutive weeks in the past year（OR=3.304

95% CI:1.58～6.909） and depression for most of the times in more than two years（OR=2.481

95% CI:1.093～5.631）were risk factors for breast cancer.The multivariate stratified analysis for pre-menopausal and post-menopausal women showed that depression for more than two consecutive weeks in the past year(OR

pre-menopausal

=4.947

95% CI:1.802～13.582;OR

post-menopausal

=4.497

95% CI:2.224～9.092) was a risk factor for breast cancer.For post-menopausal women

late age of menarche（OR=0.792

95% CI:0.675～0.929） and intake of beans（OR=0.115

95%CI:0.045～0.296） were protective factors against breast cancer

while getting irritable for most of the times in more than two years（OR=1.927

95% CI:1.007～3.687） was a risk factor for breast cancer.For pre-menopausal women

getting irritable for more than two consecutive weeks in the past year（OR=3.178

95% CI:1.31～7.709） was a risk factor for breast cancer.Conclusion:Number of abortions and emotional state（depression and irritation） are risk factors for breast cancer

and late age of menarche

high number of childbirths

and intake of beans and coarse grains are protective factors against breast cancer

with significant differences between the urban and rural areas

which should be taken seriously in developing prevention strategies for breast cancer.