Table 1.
Baseline characteristics and their relation with mammographic density decline in breast cancer patients*
| Mammographic density reduction |
|||
|---|---|---|---|
| Characteristics | No (n = 1307) | Yes (n = 1183) | P† |
| Age at diagnosis, y | <.0001 | ||
| <50 | 190 (39.6) | 290 (60.4) | |
| 50–59 | 485 (52.9) | 431 (47.1) | |
| ≥60 | 632 (57.8) | 462 (42.2) | |
| Menopausal status | <.0001 | ||
| Premenopausal | 266 (43.1) | 351 (56.9) | |
| Postmenopausal | 969 (56.5) | 747 (43.5) | |
| Unknown | 72 (45.9) | 85 (54.1) | |
| Cohort | .009 | ||
| Karma | 201 (46.7) | 229 (53.3) | |
| LIBRO1 | 1106 (53.7) | 954 (46.3) | |
| Tumor size, mm | .97 | ||
| <20 | 548 (52.4) | 498 (47.6) | |
| ≥20 | 752 (52.5) | 681 (47.5) | |
| Unknown | 7 (63.6) | 4 (36.4) | |
| No. of metastatic nodes | .25 | ||
| 0 | 1214 (52.8) | 1085 (47.2) | |
| ≥1 | 88 (48.4) | 94 (51.6) | |
| Unknown | 5 (55.6) | 4 (44.4) | |
| Grade | .28 | ||
| 1 | 140 (50.9) | 135 (49.1) | |
| 2 | 401 (54.3) | 338 (45.7) | |
| 3 | 179 (49.4) | 183 (50.6) | |
| Unknown | 587 (52.7) | 527 (47.3) | |
| Estrogen receptor status | .58 | ||
| Positive | 800 (51.6) | 749 (48.4) | |
| Negative | 118 (53.6) | 102 (46.4) | |
| Unknown | 349 (52.8) | 312 (47.2) | |
| Progesterone receptor status | .09 | ||
| Positive | 647 (50.8) | 627 (49.2) | |
| Negative | 251 (55.4) | 202 (44.6) | |
| Unknown | 409 (53.6) | 354 (46.4) | |
| HER2 status | .95 | ||
| Positive | 25 (47.2) | 28 (52.8) | |
| Negative | 218 (46.7) | 249 (53.3) | |
| Unknown | 1064 (54.0) | 906 (46.0) | |
| Family history of breast cancer | .21 | ||
| No | 1020 (51.8) | 949 (48.2) | |
| Yes | 250 (55.1) | 204 (44.9) | |
| Unknown | 37 (55.2) | 30 (44.8) | |
| BMI, kg/m2 | <.0001 | ||
| <25 | 769 (56.8) | 584 (43.2) | |
| 25–29 | 417 (49.0) | 434 (51.0) | |
| ≥30 | 121 (42.3) | 165 (57.7) | |
| Age at menarche, y | .10 | ||
| <12 | 135 (47.7) | 148 (52.3) | |
| 12–13 | 649 (51.9) | 601 (48.1) | |
| ≥14 | 523 (54.6) | 434 (45.4) | |
| Parity | .57 | ||
| 0 | 214 (54.9) | 176 (45.1) | |
| 1 | 218 (51.4) | 206 (48.6) | |
| ≥2 | 875 (52.2) | 801 (47.8) | |
| Ever use of hormonal contraception | .36 | ||
| No | 291 (54.3) | 245 (45.7) | |
| Yes | 1008 (52.1) | 928 (47.9) | |
| Unknown | 8 (44.4) | 10 (55.6) | |
| HRT use at diagnosis | .02 | ||
| Never user | 432 (58.6) | 305 (41.4) | |
| Ever user | 566 (53.2) | 497 (46.8) | |
| Unknown | 309 (44.8) | 381 (55.2) | |
| Mammogram type | .003 | ||
| Film | 977 (54.4) | 820 (45.6) | |
| Digital | 330 (47.6) | 363 (52.4) | |
| Baseline mammographic dense area, cm2 | <.0001 | ||
| <20 | 335 (57.2) | 251 (42.8) | |
| 20–39 | 578 (57.3) | 431 (42.7) | |
| ≥40 | 394 (44.0) | 501 (56.0) | |
| Follow-up mammographic dense area, cm2 | <.0001 | ||
| <20 | 252 (30.8) | 565 (69.2) | |
| 20–39 | 574 (55.1) | 467 (44.9) | |
| ≥40 | 481 (76.1) | 151 (23.9) | |
*
Mammographic density reduction was defined as an annual decrease in dense area greater than 15%. BMI= body mass index; HRT= hormone replacement therapy.
†
The Pearson χ2 test of association was used to assess the difference among groups.