Table 1.
Characteristics of the studies for meta-analysis
| Study | Year | Patient number | Patient source | Patient characteristics (previous ET) | ESR1 mutation rate | Subsequent treatment | HR estimation | HR (95% CI) of PFS | HR (95% CI) of OS |
|---|---|---|---|---|---|---|---|---|---|
| Takeshita et al17 | 2017 | 69 | Japan | About 76.8% of the MBC patients were first treated with AI and/or SERM | 28.9% (20/69) | ET | Given by author | 2.04 (1.08–3.83) | NO |
| Chandarlapaty et al13 | 2016 | 189 | BOLERO-2 study | The MBC patients were first exposed to nonsteroidal AIs | 32.3% (61/189) | Exemestane | Given by author | 1.27 (0.91–1.77) | NO |
| Fribbens et al (1)14 | 2016 | 57 | SoFEA study | Nonsteroidal AIs were given as adjuvant treatment for at least 12 months or as first-line metastatic treatment for at least 6 months | 31.6% (18/57) | Exemestane | Given by author | 2.12 (1.18–3.81) | 1.65 (0.81–3.38) |
| Fribbens et al (2)14 | 2016 | 224 | SoFEA and PALOMA-3 study | SoFEA study: the same as above PALOMA-3 study: advanced BC patients progressed during prior ET | 32.6% (73/224) | Fulvestrant | Survival curve | 0.98 (0.72–1.33) | NO |
| Clatot et al12 | 2016 | 50 for PFS 51 for OS | France | The MBC patients were first exposed to AIs | 31.4% (16/51) | Tamoxifen or fulvestrant | Given by author | 1.4 (0.8–2.8) | 1.7 (0.9–3.3) |
| Schiavon et al16 | 2015 | 45 | UK | Advanced BC patients were first treated with AIs and/or SERMs | 15.6% (7/45) | Aromatase inhibitor | Given by author | 3.1 (1.90–5.06) | NO |
| Spoerke et al15 | 2016 | 70 | USA | BC patients relapsed during or within 6 months of AI treatment in the adjuvant setting or relapsed during treatment with an AI in the metastatic setting | 43% (30/70) | Fulvestrant | Survival curve | 1.17 (0.71–1.93) | NO |
Abbreviations: AI, aromatase inhibitor; BC, breast cancer; ET, endocrine therapy; MBC, metastatic breast cancer; NO, not provided; OS, overall survival; PFS, progression-free survival; SERM, selective estrogen receptor modifiers.