Risk Analysis of Breast Cancer by Using Bilateral Mammographic Density Differences: A Case-Control Study

Risk Analysis of Breast Cancer by Using Bilateral Mammographic Density Differences: A Case-Control Study

Zhang Zhang,¹,⁴

¹Department of Intelligent Biomedical Systems Engineering Laboratory, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi, Japan
²Smart-Aging Research Center, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, Japan
³Department of General Engineering, National Institute of Technology, Sendai College, Sendai, Miyagi, Japan
⁴Department of Radiological Imaging and Informatics, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
⁵Clinical Technology Department, Tohoku University Hospital, Sendai, Miyagi, Japan
⁶Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Miyagi, Japan
⁷Department of Radiology, Akita University Graduate School of Medicine, Akita, Akita, Japan

⁹Department of Surgery, Tohoku University Hospital, Sendai, Miyagi, Japan
¹⁰Department of Breast and Endocrine Surgical Oncology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan

The identification of risk factors helps radiologists assess the risk of breast cancer. Quantitative factors such as age and mammographic density are established risk factors for breast cancer. Asymmetric breast findings are frequently encountered during diagnostic mammography. The asymmetric area may indicate a developing mass in the early stage, causing a difference in mammographic density between the left and right sides. Therefore, this paper aims to propose a quantitative parameter named bilateral mammographic density difference (BMDD) for the quantification of breast asymmetry and to verify BMDD as a risk factor for breast cancer. To quantitatively evaluate breast asymmetry, we developed a semi-automatic method to estimate mammographic densities and calculate BMDD as the absolute difference between the left and right mammographic densities. And then, a retrospective casecontrol study, covering the period from July 2006 to October 2014, was conducted to analyse breast cancer risk in association with BMDD. The study included 364 women diagnosed with breast cancer and 364 matched control patients. As a result, a significant difference in BMDD was found between cases and controls (P < 0.001) and the casecontrol study demonstrated that women with BMDD > 10% had a 2.4-fold higher risk of breast cancer (odds ratio, 2.4; 95% confidence interval, 1.3-4.5) than women with BMDD 10%. In addition, we also demonstrated the positive association between BMDD and breast cancer risk among the subgroups with different ages and the Breast Imaging Reporting and Data System (BI-RADS) mammographic density categories. This study demonstrated that BMDD could be a potential risk factor for breast cancer.

Key words —— bilateral asymmetry; breast cancer; mammographic density; mammography; risk factors

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Tohoku J. Exp. Med., 2023 October, 261(2), 139-150.

Correspondence: Zhang Zhang, Department of Intelligent Biomedical Systems Engineering Laboratory, Graduate School of Biomedical Engineering, Tohoku University, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-0872, Japan.

e-mail: zhangzhang@dc.tohoku.ac.jp