Breast cancer risk factor associations differ for pure versus invasive carcinoma with an in situ component in case-control and case-case analyses
Published Date:Nov 30 2015
Source:Cancer Causes Control. 27(2):183-198.
Carcinoma, Ductal, Breast
Carcinoma, Intraductal, Noninfiltrating
Ductal Carcinoma In Situ Component
Pubmed Central ID:PMC4724280
Funding:U58 DP003931/DP/NCCDPHP CDC HHS/United States
P30 CA016056/CA/NCI NIH HHS/United States
5U58DP003931-02/DP/NCCDPHP CDC HHS/United States
P30 CA072720/CA/NCI NIH HHS/United States
R01 CA169175/CA/NCI NIH HHS/United States
P01 CA151135/CA/NCI NIH HHS/United States
K22 CA138563/CA/NCI NIH HHS/United States
N01PC-2013-00021/PC/NCI NIH HHS/United States
R03 CA17106/CA/NCI NIH HHS/United States
R03 CA171061/CA/NCI NIH HHS/United States
R01 CA100598/CA/NCI NIH HHS/United States
Invasive ductal carcinoma (IDC) is diagnosed with or without a ductal carcinoma in situ (DCIS) component. Previous analyses have found significant differences in tumor characteristics between pure IDC lacking DCIS and mixed IDC with DCIS. We will test our hypothesis that pure IDC represents a form of breast cancer with etiology and risk factors distinct from mixed IDC/DCIS.
We compared reproductive risk factors for breast cancer risk, as well as family and smoking history between 831 women with mixed IDC/DCIS (n=650) or pure IDC (n=181), and 1,620 controls, in the context of the Women's Circle of Health Study (WCHS), a case-control study of breast cancer in African-American and European-American women. Data on reproductive and lifestyle factors were collected during interviews, and tumor characteristics were abstracted from pathology reports. Case-control and case-case analyses were conducted using unconditional logistic regression.
Most risk factors were similarly associated with pure IDC and mixed IDC/DCIS. However, among postmenopausal women, risk for pure IDC was lower in women with body mass index (BMI) 25 to <30 kg/m2 (Odds Ratio (OR)=0.66; 95% confidence interval (CI), 0.35-1.23) and BMI≥30 kg/m2 (OR=0.33; 95% CI, 0.18-0.67) compared to women with BMI<25 kg/m2, with no associations with mixed IDC/DCIS. In case-case analyses, women who breastfed up to 12 months (OR=0.55; 95% CI, 0.32-0.94) or longer (OR=0.47; 95% CI, 0.26-0.87) showed decreased odds of pure IDC than mixed IDC/DCIS compared to those who did not breastfeed.
Associations with some breast cancer risk factors differed between mixed IDC/DCIS and pure IDC, potentially suggesting differential developmental pathways. These findings, if confirmed in a larger study, will provide a better understanding of the development patterns of breast cancer and the influence of modifiable risk factors, which in turn could lead to better preventive measures for pure IDC, which have worse disease prognosis compared to mixed IDC/DCIS.
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