Table 1. Baseline characteristics of the enrolled patients, according to the presence of a gap.
| Characteristics | Gap (−) (n=3,107, 52.4%) | Gap (+)* (n=2,821, 47.6%) | p-value† | |
|---|---|---|---|---|
| Age at diagnosis (yr) | ||||
| <40 | 423 (44.1) | 536 (55.9) | <0.001 | |
| 40–49 | 1,509 (53.3) | 1,324 (46.7) | - | |
| ≥50 | 1,175 (55.0) | 961 (45.0) | - | |
| Marital status at diagnosis | ||||
| Unmarried | 122 (39.2) | 189 (60.8) | <0.001 | |
| Married | 2,969 (53.2) | 2,613 (46.8) | - | |
| Residential area | ||||
| Rural | 812 (53.9) | 695 (46.1) | 0.193 | |
| Urban | 2,288 (51.5) | 2,117 (48.5) | - | |
| Education level | ||||
| Low (≤Middle school graduation) | 791 (51.3) | 751 (48.7) | 0.186 | |
| High (>Middle school graduation) | 2,244 (53.3) | 1,969 (46.7) | - | |
| BMI (kg/m2) | ||||
| <25 | 2,277 (52.4) | 2,067 (47.6) | 0.990 | |
| ≥25 | 830 (52.4) | 754 (47.6) | - | |
| Family history of breast cancer | ||||
| No | 2,794 (52.0) | 2,581 (48.0) | 0.121 | |
| Yes | 264 (55.7) | 210 (44.3) | - | |
| Breast cancer stage | ||||
| Stage I | 1,391 (52.2) | 1,272 (47.8) | 0.013 | |
| Stage II | 1,353 (51.4) | 1,280 (48.6) | - | |
| Stage III | 363 (57.4) | 269 (42.6) | - | |
| Histology | ||||
| Invasive ductal carcinoma | 2,978 (52.2) | 2,731 (47.8) | 0.078 | |
| Invasive lobular carcinoma | 112 (58.6) | 79 (41.4) | - | |
| Histologic grade | ||||
| Grade 1 | 288 (51.2) | 275 (48.8) | 0.171 | |
| Grade 2 | 1,977 (54.7) | 1,635 (45.3) | - | |
| Grade 3 | 653 (52.6) | 588 (47.4) | - | |
| Breast surgical method | ||||
| Breast conserving surgery | 1,727 (58.9) | 1,207 (41.1) | <0.001 | |
| Mastectomy | 1,379 (46.2) | 1,606 (53.8) | - | |
| Chemotherapy | ||||
| No | 1,289 (50.5) | 1,262 (49.5) | 0.013 | |
| Yes | 1,803 (53.8) | 1,549 (46.2) | - | |
| Radiation therapy | ||||
| No | 1,082 (44.1) | 1,374 (55.9) | <0.001 | |
| Yes | 2,022 (58.5) | 1,436 (41.5) | - | |
BMI = body mass index.
*Gap (+): when the duration of treatment omission was more than 28 days; †p-value: t-test was used for age; for the other variables, the χ2 test was used. “Unknown” was treated as a missing value.