Table 1.
Selected characteristics of cohort studies with quantitative classification of percent mammographic density*
| First author/study (reference), region | Subject age, y | Sample size† | Measurement‡ | Partition§ | OR (95% CI) | Follow-up, y | Adjustments║ |
| Kato (19), USA | 35–65 | 197/521 | Planimetry | Upper vs lower tertile | 3.6 (1.4 to 9.1) | 5.5 | BMI, parity, menopause |
| Saftlas (20), USA | 35–74 | 266/301 | Planimetry | <5% vs ≥65% | 4.3 (2.1 to 8.8) | 5 | Age, weight, parity |
| Byrne (16), USA | 35–74 | 1880/2152 | Planimetry | 0% vs ≥75% | 4.3 (3.1 to 6.1) | 10 | Weight, age at first birth, family history, years of education, alcohol use, previous benign biopsies, reproductive years. |
| Torres-Mejia (21), EUR | 40–80 | 111/3100 | Computer assisted | 0.5% vs >46% | 3.5 (1.4 to 5.2) | 14 | Age, education, parity, height, BMI |
| van Gils (22), EUR | >45 | 129/517 | Automated | <5% vs >25% | 2.9 (1.6 to 5.6) | 10 | Age, parity |
| Thomas (23), USA | <50 | 547/472 | Estimation | Upper vs lower quartiles | 4.4 (3.0 to 6.7) | >6 | Age, study |
| Maskarinec (24), USA | 60¶ | 607/667 | Computer assisted | <10% vs >50% | 3.6 (2.3 to 5.6) | 7 | Ethnicity, age, BMI, age at fist birth, number of births, age at menarche, age at menopause, HRT, family history of breast cancer |
| Boyd-NBSS (25), CAN | 40–59 | 330 | Estimation | 0% vs ≥75% | 6.0 (2.8 to 13.0) | 7 | Age, parity, age at first birth, weight, height, number of births, age at menarche, family history |
| Computer assisted | 4.0 (2.1 to 7.7) | ||||||
| Boyd-SMPBC (18), CAN | 40–70 | 398 | Estimation | <10% vs ≥75% | 4.5 (1.9 to 11.0) | 6 | Age, parity, age at first birth, weight, height, number of births, age at menarche, family history |
| Computer assisted | 4.4 (2.1 to 5.0) | ||||||
| Boyd-OBSP (18), CAN | 50–69 | 386 | Estimation | <10% vs ≥75% | 3.4 (1.1 to 10.3) | 8 | Age, parity, age at first birth, weight, height, number of births, age at menarche, family history |
| Computer assisted | 4.1 (2.0 to 8.6) | ||||||
| Boyd-Combined (18), CAN | 40–70 | 1114 | Estimation | <10% vs ≥75% | 4.7 (3.0 to 7.4) | 6–8 | Age, parity, age at first birth, weight, height, number of births, age at menarche, family history |
| Computer assisted | 4.4 (2.9 to 6.7) |
BMI = body mass index; CAN = Canada; CI = confidence interval; EUR = Europe; HRT = hormone replacement therapy; NBSS = National Breast Screening Study; OBSP = Ontario Breast Screening Program; OR = odds ratio; SMPBC = Screening Mammography Program of British Columbia.
Reported as the number of case subjects/number of control subjects or as the number of pairs of case and control subjects.
Estimation means visual estimation by an observer (radiologist).
The most and least extensive categories of density from which odds ratios were calculated.
Factors included in the analysis of risk associated with mammographic density. Factors controlled for by matching are also included.
Average age.