Table 1.
Patient Characteristics in the Training and Validation Cohorts
| Patient Characteristics | Training Set (N=143) | External Validation Set (N=53) | P value |
|---|---|---|---|
| Age (years, Median ±IQR) | 59.23 (49.67–63.93) | 58.97 (53.03–68.00) | 0.998 |
| DFS (years, Median ±IQR) | 34.50 (12.90–76.13) | 33.53 (5.41–96.38) | 0.915 |
| Time from cancer diagnosis to MPE diagnosis (years, Median ±IQR) | 48.27 (26.60–107.40) | 59.40 (23.35–118.9) | 0.888 |
| AJCC-8 Stage | 0.055 | ||
| I stage | 18 (12.59) | 5 (9.43) | |
| II stage | 58 (40.56) | 13 (24.53) | |
| III stage | 48 (33.57) | 29 (54.72) | |
| IV stage | 19 (13.29) | 6 (11.32) | |
| ER/PR status | 0.868 | ||
| Positive | 109 (76.22) | 41 (77.36) | |
| Negative | 34 (23.78) | 12 (22.64) | |
| HER-2 status | 0.220 | ||
| Positive | 29 (20.27) | 8 (15.10) | |
| Negative | 101 (70.63) | 36 (67.92) | |
| Missing | 13 (9.10) | 9 (16.98) | |
| Surgical procedure | 0.414 | ||
| Modified/standard radical mastectomy | 107 (74.82) | 44 (83.02) | |
| Breast conserving surgery | 16 (11.19) | 3 (5.66) | |
| No surgery | 20 (13.99) | 6 (11.32) | |
| Chest radiotherapy | 0.905 | ||
| Yes | 58 (40.56) | 21 (39.62) | |
| No | 85 (59.44) | 32 (60.38) | |
| First appearance of distant metastasis | 0.430 | ||
| Yes | 48 (33.57) | 21 (39.62) | |
| No | 95 (66.43) | 32 (60.38) | |
| Menopausal status | 0.943 | ||
| Postmenopausal | 122 (85.31) | 45 (84.91) | |
| Menopausal | 21 (14.69) | 8 (15.10) | |
| Visceral metastatic | 0.765 | ||
| Yes | 95 (66.43) | 34 (64.15) | |
| No | 48 (33.57) | 19 (35.85) | |
| Site of pleural effusions | 0.050 | ||
| Ipsilateral | 71 (49.65) | 18 (33.96) | |
| Contralateral/Bilateral | 72 (50.35) | 35 (66.04) | |
| Peritoneal effusion | 0.362 | ||
| Yes | 14 (9.79) | 3 (5.66) | |
| No | 129 (90.21) | 50 (94.34) | |
| Pericardial effusion | 0.294 | ||
| Yes | 25 (17.48) | 6 (11.32) | |
| No | 118 (82.52) | 47 (88.68) |
Abbreviations: SD, standard deviation; IQR, interquartile range; AJCC-8, the eighth edition of the American Joint Committee on Cancer; DFS, disease-free survival; ER, estrogen receptor; PR, progesterone receptor; HER-2, human epidermal growth factor receptor 2.