Table 4.
Association of %MD categories prior to/at first diagnosisa and post diagnosisb with CBC risk by family historyc
| CBC Number (%) |
UBC Number (%) |
ORd (95% CI) | |
|---|---|---|---|
| Percent mammographic density prior to/at diagnosis | |||
| No family history | |||
| <25% | 44 (27) | 64 (31) | 0.73 (0.42, 1.27) |
| 25 to <50% | 81 (49) | 97 (46) | 1.00 |
| ≥50% | 40 (24) | 48 (23) | 0.96 (0.54, 1.70) |
| Family history | |||
| <25% | 22 (26) | 16 (29) | 0.95 (0.32, 2.86) |
| 25 to <50% | 43 (51) | 30 (55) | 1.00 |
| ≥50% | 20 (24) | 9 (16) | 2.19 (0.62, 7.73) |
| p interaction | 0.50 | ||
| Post diagnosis | |||
| No family history | |||
| <25% | 86 (39) | 132 (46) | 0.76 (0.50, 1.15) |
| 25 to <50% | 102 (47) | 124 (44) | 1.00 |
| ≥50% | 30 (14) | 28 (10) | 1.28 (0.69, 2.36) |
| Family history | |||
| <25% | 41 (37) | 46 (53) | 0.53 (0.25, 1.14) |
| 25 to <50% | 47 (43) | 28 (33) | 1.00 |
| ≥50% | 22 (20) | 12 (14) | 1.55 (0.57, 4.22) |
| p interaction | 0.59 | ||
Abbreviations: %MD percent mammographic density, CBC contralateral breast cancer, UBC unilateral breast cancer, OR odds ratio, CI confidence interval
aPrior to/at 1st diagnosis was 36 months prior up to 1 month post diagnosis
bPost diagnosis was > 6 months up to 48 months post diagnosis
cFamily history is defined as having a first-degree relative (mother, sister, daughter) with breast cancer, women with unknown family history were excluded.
dOR adjusted for study center, race (non-Hispanic white versus other), age at mammogram, menopausal status at mammogram, estimated body mass index at mammogram, age at first diagnosis, age at menarche, number of full-term pregnancies, histologic type, stage, and estrogen receptor status of first diagnosis, chemotherapy, radiation, and tamoxifen use after first diagnosis