Table 1. Clinicopathologic Characteristics of Breast Cancer Patients from SEER Database by Primary Site.
| No. (%) of Patients | |||||||
| Total (n = 305,443) | UO (n = 169,346) | UI (n = 51,303) | LI (n = 26,603) | LO (n = 32,618) | CEN (n = 25,573) | ||
| Characteristics | P | ||||||
| Median Follow-up (mo) (IUR) | 72.0 (38–116) | 74.0 (39–118) | 70.0 (36–113) | 70.0 (29–114) | 69.0 (37–113) | 73.0 (38–118) | |
| Patient age (y) | <.0001 | ||||||
| 20–39 | 18,557 (6.1) | 10,741 (6.3) | 3,089 (6.0) | 1,365 (5.1) | 2,140 (6.6) | 1,222 (4.8) | |
| 40–59 | 143,867 (47.1) | 81,227 (48.0) | 24,597 (47.9) | 11,814 (44.4) | 15,347 (47.1) | 10,882 (42.6) | |
| 60–79 | 143,019 (46.8) | 77,378 (45.7) | 23,617 (46.0) | 13,424 (50.5) | 15,131 (46.4) | 13,469 (52.7) | |
| Year of Diagnosis | <.0001 | ||||||
| 1990–1994 | 33,601 (11.0) | 19,782 (11.7) | 4,970 (9.7) | 2,683 (10.1) | 3,262 (10.0) | 2,904 (11.4) | |
| 1995–1999 | 47,100 (15.4) | 26,595 (15.7) | 7,350 (14.3) | 3,995 (15.0) | 4,735 (14.5) | 4,425 (17.3) | |
| 2000–2004 | 104,619 (34.3) | 58,274 (34.4) | 17,416 (33.9) | 9,201 (34.6) | 10,985 (33.7) | 8,743 (34.2) | |
| 2005–2009 | 120,123 (39.3) | 64,695 (38.2) | 21,567 (42.0) | 10,724 (40.4) | 13,636 (41.8) | 9,501 (37.2) | |
| Tumor Size | <.0001 | ||||||
| 0–2 cm | 204,014 (66.8) | 110,871 (65.5) | 35,797 (69.8) | 19,461 (73.2) | 22,220 (68.1) | 15,665 (61.3) | |
| 2–5 cm | 89,438 (29.3) | 51,120 (30.2) | 14,012 (27.3) | 6,589 (24.8) | 9,467 (29.0) | 8,250 (32.3) | |
| >5 cm | 11,991 (3.9) | 7,355 (4.3) | 1,494 (2.9) | 553 (2.1) | 931 (2.9) | 1,658 (6.5) | |
| LN Status | <.0001 | ||||||
| Negative | 210,240 (68.8) | 112,361 (66.3) | 40,089 (78.1) | 20,038 (75.3) | 21,708 (66.6) | 16,044 (62.7) | |
| Positive | 95,203 (31.2) | 56,985 (33.7) | 11,214 (21.9) | 6,565 (24.7) | 10,910 (33.4) | 9,529 (37.3) | |
| ER Status | <.0001 | ||||||
| Negative | 68,085 (22.3) | 39,124 (23.1) | 11,450 (22.3) | 5,942 (22.3) | 6,927 (21.2) | 4,642 (18.2) | |
| Positive | 237,358 (77.7) | 130,222 (76.9) | 39,853 (77.7) | 20,661 (77.7) | 25,691 (78.8) | 20,931 (81.8) | |
| PR Status | <.0001 | ||||||
| Negative | 99,709 (32.6) | 56,484 (33.4) | 16,482 (32.1) | 8,622 (32.4) | 10,467 (32.1) | 7,654 (29.9) | |
| Positive | 205,734 (67.4) | 112,862 (66.6) | 34,821 (67.9) | 17,981 (67.6) | 22,151 (67.9) | 17,919 (70.1) | |
| Radiotherapy | <.0001 | ||||||
| Without RT | 139,306 (45.6) | 75,267 (44.4) | 22,212 (43.3) | 12,267 (46.1) | 15,294 (46.9) | 14,266 (55.8) | |
| With RT | 166,137 (54.4) | 94,079 (55.6) | 29,091 (56.7) | 14,336 (53.9) | 17,324 (53.1) | 11,307 (44.2) | |
| Laterality | <.0001 | ||||||
| Left-sided | 155,126 (50.8) | 84,246 (49.7) | 26,792 (52.2) | 14,169 (53.3) | 16,926 (51.9) | 12,993 (50.8) | |
| Right-sided | 150,317 (49.2) | 85,100 (50.3) | 24,511 (47.8) | 12,434 (46.7) | 15,692 (48.1) | 12,580 (49.2) | |
Abbreviations: UO = upper outer quadrant of breast; UI = upper inner quadrant of breast; LI = lower inner quadrant of breast; LO = lower outer quadrant of breast; CEN = central portion quadrant of breast; IUR = interquartile range; LN = lymph node; ER = estrogen receptor; PR = progesterone receptor; RT = radiotherapy.