Table 2 Mammographic density measurements for cases and controls, by mode of detection (screen-detected or interval cancer)
| Â | Interval cancer | Screen-detected cancer | ||||
|---|---|---|---|---|---|---|
Cases (n = 168) Mean (SD) | Controls (n = 498) Mean (SD) | P a | Cases (n = 422) Mean (SD) | Controls (n = 1197) Mean (SD) | P a | |
Cumulus | ||||||
 Dense area (cm2) | 25 (13) | 19 (11) | < 0.001 | 21 (13) | 19 (12) | 0.001 |
 Non-dense area (cm2) | 110 (54) | 126 (56) | 0.001 | 132 (59) | 127 (55) | 0.2 |
 Percent dense area | 21 (11) | 15 (9) | < 0.001 | 16 (10) | 14 (9) | 0.01 |
 Total area (cm2) | 135 (56) | 145 (56) | 0.04 | 153 (58) | 146 (55) | 0.04 |
Altocumulus | ||||||
 Dense area (cm2) | 12 (8) | 9 (7) | < 0.001 | 10 (7) | 9 (8) | 0.01 |
 Non-dense area (cm2) | 124 (57) | 137 (57) | 0.008 | 144 (59) | 138 (55) | 0.09 |
 Percent dense area | 11 (8) | 7 (6) | < 0.001 | 7 (6) | 7 (6) | 0.04 |
 Total area (cm2) | 136 (57) | 146 (57) | 0.05 | 154 (59) | 147 (55) | 0.04 |
Cirrocumulus | ||||||
 Dense area (cm2) | 6.8 (6.2) | 4.2 (4.6) | < 0.001 | 4.8 (5.3) | 3.9 (4.9) | 0.002 |
 Non-dense area (cm2) | 129 (55) | 141 (56) | 0.01 | 148 (58) | 142 (55) | 0.09 |
 Percent dense area | 6.0 (5) | 3.0 (4) | < 0.001 | 4.0 (4) | 3.0 (3) | 0.003 |
 Total area (cm2) | 135 (56) | 145 (56) | 0.05 | 153 (58) | 146 (55) | 0.05 |