Table 1.
Clinical, pathological and immunohistochemical characteristics of HER2 low breast cancers
| Variable | Overall (98) | HER2-1+ (55) | HER2-2+ (43) | P-value |
|---|---|---|---|---|
| N(%) or mean | N(%) or mean | N(%) or mean | ||
| Age at primary diagnosis/y | 50.5 ± 11.6 | 50.3 ± 11.3 | 51.7 ± 11.6 | 0.552 |
| Tumor size | 0.089 | |||
| - ≤ 2 cm | 22 (22.4) | 16 (29.1) | 6 (14.0) | |
| - > 2 cm | 47 (48.0) | 24 (43.6) | 23 (53.4) | |
| -Unavailable | 29 (29.6) | 15 (27.3) | 14 (32.6) | |
| Histological subtype | 1.000 | |||
| -Invasive breast carcinoma NOS | 93 (94.9) | 52 (94.5) | 41 (95.3) | |
| -Others | 5 (5.1) | 3 (5.5) | 2 (4.7) | |
| Histological grade | 0.459 | |||
| -II | 52 (51.0) | 31 (56.4) | 21 (48.8) | |
| -III | 46 (45.9) | 24 (43.6) | 22 (51.2) | |
| Estrogen receptor expression | 0.697 | |||
| -Positive | 77 (78.6) | 44 (80.0) | 33 (76.7) | |
| -Negative | 21 (21.4) | 11 (20.0) | 10 (23.3) | |
| Progesterone receptor expression | 0.579 | |||
| -Positive | 60 (61.2) | 35 (63.6) | 25 (58.1) | |
| -Negative | 38 (38.8) | 20 (36.4) | 18 (41.9) | |
| Ki67 | 0.371 | |||
| - < 20% | 15 (15.3) | 10 (18.2) | 5 (11.6) | |
| - ≥ 20% | 83 (84.7) | 45 (81.8) | 38 (88.4) | |
| Age at metastasis diagnosis | 53.0 ± 11.7 | 52.2 ± 11.3 | 53.9 ± 11.8 | 0.471 |
| Site of metastasis | 0.929 | |||
| -Bone | 13 (13.3) | 8 (14.5) | 5 (11.6) | |
| -Lung/Pleura | 28 (28.6) | 15 (27.3) | 13 (30.2) | |
| -Liver | 41 (41.8) | 24 (43.6) | 17 (39.5) | |
| -Skin and soft tissues | 11 (11.2) | 6 (10.9) | 5 (11.6) | |
| -Others | 5 (5.1) | 2 (3.6) | 3 (7.0) |