Efficacy of Fulvestrant in Women with Hormone-Resistant Metastatic Breast Cancer (mBC): A Canadian Province Experience.
INTRODUCTION
Fulvestrant has demonstrated efficacy in hormone receptor positive (HR+) metastatic breast cancer (mBC), both in first-and second-line settings. In clinical practice, however, fulvestrant has been used as a later-line therapy. This study assessed the efficacy of fulvestrant in women with mBC in early-versus later-line therapy.


METHODS
This retrospective cohort study assessed Saskatchewan women with HR+ mBC who received fulvestrant between 2003-2019. A multivariate Cox proportional survival analysis was performed.


RESULTS
One hundred and eighty-six women with a median age of 63.5 years were identified-178 (95.6%) had hormone-resistant mBC, 57.5% had visceral disease, and 43.0% had received chemotherapy before fulvestrant. 102 (54.8%) women received ≤2-line-therapy, and 84 (45.2%) received ≥3 line-therapy before fulvestrant. The median time to progression (TTP) was 12 months in the early-treatment vs. 6 months in the later-treatment group, p = 0.015. Overall survival (OS) from the start of fulvestrant was 26 months in the early-treatment group vs. 16 months in the later-treatment group, p = 0.067. On multivariate analysis, absence of visceral metastasis, HR: 0.70 (0.50-0.99), was significantly correlated with better TTP, whereas post-fulvestrant chemotherapy, HR: 0.32 (0.23-0.47), clinical benefit from fulvestrant, HR: 0.44 (0.30-0.65), and absence of visceral metastasis, HR: 0.70 (0.50-0.97), were correlated with better OS.


CONCLUSIONS
Fulvestrant has demonstrated efficacy as both early-and later-line therapy in hormone-resistant mBC. Our results show that women with clinical benefit from fulvestrant, who received post-fulvestrant chemotherapy, or had non-visceral disease, had better survival.
['Andrahennadi|Samitha|S|0000-0002-6716-6908', 'Sami|Amer|A|', 'Haider|Kamal|K|', 'Chalchal|Haji Ibraheem|HI|', 'Le|Duc|D|', 'Ahmed|Osama|O|0000-0001-9241-7695', 'Manna|Mita|M|', 'El-Gayed|Ali|A|', 'Wright|Philip|P|', 'Ahmed|Shahid|S|0000-0002-2099-698X']
fulvestrant hormone-resistant survival hormone receptor positive breast cancer visceral metastases