Table 1 Main characteristics of case-control/cross-sectional studies included in the meta-analysis
S.no. | First author, year (ref) | Study design | Region | Adj: variables adjusted | Type of BC Invasive or invasive and DCIS | Mammographic density categories [no/little, low, medium, high] | Age Mean (SD) or range | Controls (n) | Breast cancer cases (n) | Quality score by NOS/AHRQ |
|---|---|---|---|---|---|---|---|---|---|---|
1 | Du, 2009 [15] | Case-control | Beijing | Age | Both | BI-RADSa [1, 2, 3, 4] | 22 ~ 88 | 1559 | 62 | 6 |
2 | Dai, 2014 [16] | Cross-sectional | Tianjin, Nanchang, Beijing, Shenyang | Age, BMI, study area, and other variables | Both | BI-RADSa [1, 2, 3, 4] | 45 ~ 65 | 28,302 | 86 | 10 |
3 | Chen, 2015 [17] | Case-control | Harbin | Not formally age-adjusted | Both | BI-RADSa [1, 2, 3, 4] | Cannot retrieve data but a wide range | 382 | 105 | 7 |
4 | Wu, 2015 [18] | Case-control | Kunshan | Age | Both | BI-RADSa [1, 2, 3, 4] | 19 ~ 82 | 4102 | 139 31:26c (premenopausal: postmenopausal) | 6 |
5 | Yang, 2016 [19] | Cross-sectional | Guangzhou | BMI, age, duration of breastfeeding, and other variables | Both | BI-RADSa [1, 2, 3, 4] | 27 ~ 57(premenopausal) | 1689 | 10 | 8 |
6 | Yu, 2016 [20] | Case-control | Cangzhou | Age | Both | BI-RADSa [1, 2, 3, 4] | 22 ~ 85 | 4822 | 184 128:56 (premenopausal: postmenopausal) | 7 |
7 | Du, 2019 [22] | Case-control | Harbin | Age, menopausal status, and breastfeeding | Both | BI-RADSa [1, 2, 3, 4] | Cannot retrieve data but a wide range | 588 | 237 131:106 (premenopausal: postmenopausal) | 7 |
8 | Ye, 2019 [24] | Case-control | Shenyang | Age, menopausal status, age at menopause, and other variables | Both | BI-RADSa [1, 2, 3, 4] | 57 (5.1) | 2284 | 735 | 8 |
9 | Wang, 2020 [25] | Case-control | Taiyuan | BMI, menstrual status, and other variables | Both | BI-RADSb [1, 2, 3, 4] Quantra classification [1, 2, 3, 4] | 26 ~ 81 | 932 | 466 | 7 |
10 | Xu, 2021 [27] | Case-control | Ningbo | Age, menopausal status, and other variables | Both | BI-RADSa [1, 2, 3, 4] | Cannot retrieve data but a wide range | 5730 | 270 | 8 |