Table 1.
Baseline characteristics of patients with OBC and non-OBC.
| Characteristics | OBC (n = 572) | Non-OBC (n = 117,217) | Total (n = 117,789) | Pc | ||||
|---|---|---|---|---|---|---|---|---|
| No | % | No | % | No | % | |||
| Median follow-up (months) (IQR) | 61.5 (30–100.75) | 63 (33–102) | 63 (33–102) | |||||
| Year of diagnosis | 2004–2009 | 254 | 44.4 | 55,784 | 47.6 | 56,038 | 47.6 | 0.128 |
| 2010–2015 | 318 | 55.6 | 61,433 | 52.4 | 61,751 | 52.4 | ||
| Age (years) | 20–49 | 136 | 23.8 | 40,798 | 34.8 | 40,934 | 34.8 | <0.001 |
| 50–79 | 436 | 76.2 | 76,419 | 65.2 | 76,855 | 65.2 | ||
| Race | White | 450 | 78.7 | 91,273 | 77.9 | 91,723 | 77.9 | 0.536 |
| Black | 76 | 13.3 | 14,957 | 12.8 | 15,033 | 12.8 | ||
| Othera | 46 | 8.0 | 10,987 | 9.4 | 11,033 | 9.4 | ||
| Marital status | Married | 340 | 59.4 | 72,521 | 61.9 | 72,861 | 61.9 | 0.233 |
| Not marriedb | 232 | 40.6 | 44,696 | 38.1 | 44,928 | 38.1 | ||
| Laterality | Left | 306 | 53.5 | 59,336 | 50.6 | 59,642 | 50.6 | 0.170 |
| Right | 266 | 46.5 | 57,881 | 49.4 | 58,147 | 49.4 | ||
| Grade | I and II | 29 | 5.1 | 62,896 | 53.7 | 62,925 | 53.4 | <0.001 |
| III and IV | 132 | 23.1 | 50,422 | 43.0 | 50,554 | 42.9 | ||
| Unknown | 411 | 71.9 | 3,899 | 3.3 | 4,310 | 3.7 | ||
| AJCC stage | II | 368 | 64.3 | 78,516 | 67.0 | 78,884 | 67.0 | 0.179 |
| III | 204 | 35.7 | 38,701 | 33.0 | 38,905 | 33.0 | ||
| Nodal status | 1 to 3 | 368 | 64.3 | 86,604 | 73.9 | 86,972 | 73.8 | <0.001 |
| 4 to 9 | 105 | 18.4 | 20,636 | 17.6 | 20,741 | 17.6 | ||
| >9 | 99 | 17.3 | 9,977 | 8.5 | 10,076 | 8.6 | ||
| ER status | Positive | 302 | 52.8 | 90,613 | 77.3 | 90,915 | 77.2 | <0.001 |
| Negative | 221 | 38.6 | 23,750 | 20.3 | 23,971 | 20.4 | ||
| Others | 49 | 8.6 | 2,854 | 2.4 | 2,903 | 2.5 | ||
| PR status | Positive | 202 | 35.3 | 77,786 | 66.4 | 77,988 | 66.2 | <0.001 |
| Negative | 310 | 54.2 | 35,779 | 30.5 | 36,089 | 30.6 | ||
| Others | 60 | 10.5 | 3,652 | 3.1 | 3,712 | 3.2 | ||
| HER-2 status | Positive | 88 | 15.4 | 11,478 | 9.8 | 11,566 | 9.8 | <0.001 |
| Negative | 185 | 32.3 | 47,530 | 40.5 | 47,715 | 40.5 | ||
| Others | 299 | 52.3 | 58,209 | 49.7 | 58,508 | 49.7 | ||
| Breast subtype | Her2+/HR+ | 54 | 9.4 | 7,981 | 6.8 | 8,035 | 6.8 | <0.001 |
| Her2+/HR- | 32 | 5.6 | 3,477 | 3.0 | 3,509 | 3.0 | ||
| Her2-/HR+ | 114 | 19.9 | 40,574 | 34.6 | 40,688 | 34.5 | ||
| Triple negative | 71 | 12.4 | 6,904 | 5.9 | 6,975 | 5.9 | ||
| Unknown | 301 | 52.6 | 58,281 | 49.7 | 58,582 | 49.7 | ||
| Mastectomy | Yes | 202 | 35.3 | 66,315 | 56.6 | 66,517 | 56.5 | <0.001 |
| No | 370 | 64.7 | 50,902 | 43.4 | 51,272 | 43.5 | ||
| Chemotherapy | Yes | 480 | 83.9 | 88,848 | 75.8 | 89,328 | 75.8 | <0.001 |
| No/Unknown | 92 | 16.1 | 28,369 | 24.2 | 28,461 | 24.2 | ||
| Radiation | Yes | 320 | 55.9 | 65,740 | 56.1 | 66,060 | 56.1 | 0.769 |
| No | 252 | 44.1 | 51,477 | 43.9 | 51,729 | 43.9 | ||
OBC, occult breast cancer; non-OBC, non-occult breast cancer; AJCC, American Joint Committee on Cancer; ER, estrogen receptor; PR, progesterone receptor; HER-2, human epidermal growth factor receptor-2; HR, hormone receptor; IQR, interquartile range.
a
Other includes American Indian/Alaskan native and Asian/Pacific Islander and Unknown.
b
Not married includes divorced, separated, single (never married), unmarried or domestic partner, and widowed.
c
The P-value of the Chi-square test was calculated between the OBC and non-OBC groups, and bold type indicates significance.