Table 2.
Strength of Evidence Assessment
| Prognostic Factor |
Type of Outcome |
No. of Studies That Assessed Association |
No. of Studies Reporting Significant Association |
No. of Studies with Univariate Analysis |
No. of Studies with Significant Univariate Analysis |
No. of Studies with Multivariate Analysis |
No. of Studies with Significant Multivariate Analysis |
Consistency Based on >50% Studies with Significant Association |
Directionality of Relationship |
Strength of Association Based on Effect Size |
Studies with Low Sample Size (<100) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| PR status | OS | 10 | 8 | 10 | 8 | 7 | 5 | Consistent | Consistent | Moderate | 4 |
| PFS | 2 | 1 | 1 | 0 | 0 | 0 | Inconsistent | NA (single study) | NA | 1 | |
| Tumor grade | OS | 21 | 13 | 15 | 7 | 15 | 11 | Consistent | Consistent | Moderate | 4 |
| PFS | 4 | 3 | 2 | 1 | 2 | 1 | Consistent | Consistent | Strong | 2 | |
| Tumor size | OS | 12 | 5 | 10 | 4 | 8 | 5 | Inconsistent | Consistent | Weak– moderate |
4 |
| Lymph node | OS | 11 | 4 | 10 | 4 | 5 | 1 | Inconsistent | Inconsistent | Moderate | 5 |
| PFS | 1 | 1 | 1 | 1 | 0 | 0 | NA (single study) | NA (single study) | NA | 1 | |
| Histological type | OS | 5 | 1 | 4 | 0 | 1 | 1 | Inconsistent | NA | Strong | 3 |
| PFS | 2 | 1 | 1 | 0 | 2 | 1 | Inconsistent | NA (single study) | Strong | 2 | |
| CTC count | OS | 10 | 9 | 9 | 8 | 7 | 7 | Consistent | Consistent | Strong | 3 |
| PFS | 10 | 8 | 8 | 5 | 6 | 6 | Consistent | Consistent | Moderate | 3 | |
| Ki67 | OS | 7 | 6 | 6 | 5 | 4 | 3 | Consistent | Consistent | Moderate | 2 |
| PFS | 4 | 4 | 3 | 3 | 3 | 3 | Consistent | Consistent | Moderate | 2 | |
| De novo metastatic BC | OS | 5 | 5 | 4 | 4 | 5 | 2 | Consistent | Consistent | Weak | 0 |
| PFS | 3 | 2 | 2 | 1 | 2 | 1 | Consistent | Inconsistent | Moderate | 1 | |
| No. of Metastatic sites |
OS | 27 | 24 | 21 | 19 | 20 | 14 | Consistent | Consistent | Moderate | 3 |
| PFS | 11 | 6 | 7 | 4 | 9 | 5 | Consistent | Consistent | Moderate | 2 | |
| Site of metastasis | OS | 34 | 22 | 21 | 14 | 25 | 19 | Consistent | Consistent | Moderate | 7 |
| PFS | 13 | 10 | 7 | 6 | 10 | 6 | Consistent | Consistent | Moderate | 4 | |
| Time to recurrence or progression to ABC | OS | 18 | 14 | 12 | 10 | 12 | 9 | Consistent | Consistent | Moderate | 4 |
| PFS | 5 | 4 | 3 | 3 | 4 | 3 | Consistent | Consistent | Moderate | 3 | |
| Prior therapy | OS | 35 | 27 | 24 | 18 | 25 | 22 | Consistent | Consistent | Moderate | 6 |
| PFS | 15 | 13 | 10 | 8 | 12 | 10 | Consistent | Consistent | Moderate | 6 | |
| Performance | OS | 14 | 11 | 7 | 6 | 11 | 8 | Consistent | Consistent | Moderate | 2 |
| PFS | 8 | 4 | 3 | 1 | 6 | 4 | Inconsistent | Consistent | Moderate | 1 | |
| Age | OS | 37 | 17 | 25 | 10 | 24 | 13 | Inconsistent | Consistent | Weak– Moderate |
5 |
| PFS | 7 | 2 | 5 | 0 | 3 | 2 | Inconsistent | Consistent | Moderate– Strong |
2 | |
| Race | OS | 13 | 7 | 10 | 6 | 10 | 6 | Consistent | Consistent | Weak | 1 |
| PFS | 1 | 0 | 0 | 0 | 1 | 0 | NA | NA | NA | 0 |
Abbreviations: BC, breast cancer; BCSS, breast cancer-specific survival; CTC, circulating tumor cell; NA, not applicable; OS, overall survival; PFS, progression-free survival; PR, progesterone receptor.