Table 2.
Comparison of clinical and pathologic characteristics according to laterality in women with stage I, ER+ breast cancer treated with breast conserving surgery and adjuvant radiation (n = 41,006)
| Characteristic | Right sided breast cancer (n = 20,324) | Left sided breast cancer (n = 20,682) | P value | ||
|---|---|---|---|---|---|
| Age, n (%) | |||||
| 60-69 y | 11,135 | (54.8) | 11,350 | (54.9) | .89 |
| 70-79 y | 7055 | (34.7) | 7191 | (34.8) | |
| 80+ y | 2134 | (10.5) | 2141 | (10.4) | |
| Race, n (%) | |||||
| Non-Hispanic white | 15,917 | (78.3) | 16,238 | (78.5) | .67 |
| Non-Hispanic black | 1230 | (6.1) | 1196 | (5.8) | |
| Asian | 1260 | (6.2) | 1283 | (6.2) | |
| Hispanic | 1747 | (8.6) | 1808 | (8.7) | |
| Other | 170 | (0.8) | 157 | (0.8) | |
| Tumor location, n (%) | |||||
| Central/NAC | 865 | (4.3) | 903 | (4.4) | <.001 |
| Upper inner quadrant | 2821 | (13.9) | 3238 | (15.7) | |
| Lower inner quadrant | 1379 | (6.8) | 1542 | (7.5) | |
| Upper outer quadrant | 7717 | (38.0) | 7554 | (36.5) | |
| Lower outer quadrant | 1571 | (7.7) | 1579 | (7.6) | |
| Overlapping quadrants/breast NOS | 5971 | (29.4) | 5866 | (28.4) | |
| Tumor grade, n (%) | |||||
| Grade I | 7996 | (39.3) | 7855 | (38.0) | .01 |
| Grade II | 9363 | (46.1) | 9680 | (46.8) | |
| Grade III | 2325 | (11.4) | 2409 | (11.7) | |
| Unknown | 640 | (3.2) | 738 | (3.6) | |
| Tumor size, n (%) | |||||
| 0.1-0.5 cm | 2833 | (13.9) | 2992 | (14.5) | .13 |
| 0.6-1.0 cm | 7311 | (36.0) | 7515 | (36.3) | |
| 1.1-2.0 cm | 10,180 | (50.1) | 10,175 | (49.2) | |
| Hormone receptor status, n (%) | |||||
| ER+/PR+ | 17,232 | (84.8) | 17,574 | (85.0) | .60 |
| ER+/PR- | 2793 | (13.7) | 2787 | (13.5) | |
| PR unknown | 299 | (1.5) | 321 | (1.6) | |
| HER2/neu receptor status, n (%)∗ | |||||
| HER2/neu amplified | 511 | (6.1) | 534 | (6.2) | .70 |
| HER2/neu negative | 7904 | (93.9) | 8017 | (93.8) | |
| Axillary management, n (%) | |||||
| No nodes removed | 1360 | (6.7) | 1280 | (6.2) | <.001 |
| 1-5 nodes removed (SLNB) | 15,184 | (74.7) | 15,845 | (76.6) | |
| 6 or more nodes removed (ALND) | 3708 | (18.2) | 3501 | (16.9) | |
| Unknown | 72 | (0.4) | 56 | (0.3) | |
| Adjuvant chemotherapy, n (%) | |||||
| Yes | 1607 | (7.9) | 1637 | (7.9) | .98 |
| No/unknown | 18,717 | (92.1) | 19,045 | (92.1) | |
Abbreviations: ALND = axillary lymph node dissection; ER = estrogen receptor; HERs = human-epidermal growth factor receptor 2; NAC = nipple areola complex; NOS = not otherwise specified; PR = progesterone receptor; SLNB = sentinel lymph node biopsy.
∗
HER2/neu receptor status only available for cases diagnosed from 2010 to 2015.