Table 1.
Summary characteristics of the studies on association between Vitamin D and mammographic breast density
| Study haracteristic | n (%) | Sample size range | Total sample size across all studies |
|---|---|---|---|
| Study population | |||
| Breast cancer survivors (postmenopausal only) | 1 (7%) | 426 | 426 |
| Healthy women | 13 (93%) | 99–1,668 | 10,339 |
| Premenopausal/Perimenopausala | 11 (79%) | 38–777 | 3,739 |
| Postmenopausal* | 11 (79%) | 61–1,244 | 5,863 |
| Race/Ethnicity | |||
| Predominantly white | 9 (64%) | 157–1,668 | 9,013 |
| Hispanic | 1 (7%) | 99 | 1,471 |
| Mixed | 4 (29%) | 182–808 | 1,653 |
| Study design | |||
| Prospective | 2 (14%) | 1,161–1,668 | 2,829 |
| Cross-sectional | 12 (86%) | 99–1,560 | 7,936 |
| Exposure (Vitamin D) assessment | |||
| Food frequency questionnaire | 2 (14%) | 237–1,668 | 1,905 |
| Food frequency questionnaire + supplements | 7 (50%) | 99–1,560 | 5,329 |
| Dietary 5-day recording | 1 (7%) | 1,161 | 1,161 |
| Circulating 25(OH)D levels | 5 (36%) | 182–960 | 2,796 |
| Circulating 1,25(OH)2D levels | 1 (7%) | 960 | 960 |
| Breast density assessment approach | |||
| Percent breast density (continuous) | 12 (86%) | 99–1,560 | 8,940 |
| Categorical breast density | 2 (14%) | 157–1,668 | 1,825 |
a
One study did not report the exact number of pre- and postmenopausal women in the study population