Aromatase inhibitors (AIs) with or without GnRH agonist as first-line hormone therapy in pre- and post-menopausal Korean women with metastatic breast cancer (MBC): Clinical outcomes in correlation with tumor ER/PR/HER2 status

Abstract

10732 Background: Clinical outcomes of patients (pts) with MBC by AIs in comprehensive relationship with ER/PR/HER2 status have been scant that the study was performed to analyze their predictive values singly and in combination. Methods: 111 pts who took letrozole or anastrozole as first-line hormonal therapy for MBC were identified from the database at NCC Hospital between Nov. 2001 and Aug. 2005. Pts on AIs concomitantly with or immediately followed by chemotherapy were excluded. AIs/GnRH agonists were used when hormonal levels were not postmenopausal. ER/PR were scored strong, intermediate or weak. HER2+ was IHC 3+ or FISH+. HER2− was IHC 0, 1+ or 2+/FISH−. Clinical benefit (CB) included CR/PR/improving or SD ≥6 months. Results: Median age was 54 years (range, 29–78). Overall 66% achieved CB (CR/PR 18%, improving 26%, and SD ≥ 6mo 22%) with median TTP, 9 mo (range, 1–50, 95% CI, 7–11), and median survival, 41 mo (range, 2–50). Age, AIs with (20) vs. without (91) GnRH agonist, DFI ≤ vs. > 24 mo, adjuvant tamoxifen, or prior metastatic chemotherapy did not affect clinical outcomes. Disease sites (%) were bone (64), LN (52), lung/pleura (41), liver (25), breast (20) and skin (7). Bone only disease had longer TTP (p = 0.004), while liver involvement was associated with short TTP (p = 0.0001)/OS (p = 0.007). ER was 56% strong +, 21% intermediate +, 15% weak +, 5% - and 3% unknown, PR: 24% strong +, 23% intermediate +, 24% weak +, 23% -, and 5% unknown, and HER2: 23% +, 67% -, and 10% unknown. Staining intensity did not affect CB in ER+ tumors. More CB (p = 0.002)/longer TTP (p = 0.003) with strong/intermediate PR+ tumors vs. weak PR+/PR− tumors, and more CB with ER+/PR+ tumors vs. ER+/PR− tumors (P = 0.016) were observed. More CB with HER2− tumors vs. HER2+ tumors (p = 0.001), and with PR+/HER2− tumors vs. the rest (PR−/HER−, PR+/HER+, PR−/HER+) (p = 0.0007) were seen. HER2 positivity was associated with less CB (p = 0.0004)/shorter TTP (p = 0.0157) in ER+/PR+ tumors vs. no influence on CB (p = 0.245)/TTP (p = 0.52) in ER+/PR− tumors. Conclusions: AIs with or without GnRH agonist are effective therapy for pts with MBC, specifically with ER+/PR+/HER2− tumors regardless of ages. No significant financial relationships to disclose.