Table 4.

PFS analysis stratified by hormone receptor conversion and first-line therapy (multivariable model).

PFS (time since the earliest metastasis diagnosis)	No. of patients	No. of progressions	Adjusted HR† 95% CI	p-value
Hormone receptor gain and first-line endocrine therapy
Hormone receptor gain, endocrine therapy (−)	17	15	1.000 (reference)
Hormone receptor gain, endocrine therapy (+)	24	20	0.382 (0.185–0.790)	0.009
PFS (time since the earliest metastasis diagnosis)	No. of patients	No. of progressions	Adjusted HR† 95% CI	p-value
ER gain and first-line endocrine therapy
ER gain, endocrine therapy (−)	10	7	1.000 (reference)
ER gain, endocrine therapy (+)	17	12	0.333 (0.114–0.978)	0.04

^†After adjustment for age of first metastasis diagnosis (continuous), HER2 status in metastatic site, site of metastasis (local and distant metastasis), and first-line therapy (chemotherapy and anti-HER2 therapy).

CI, confidence interval; ER, estrogen receptor; HER2, human epidermal growth factor receptor 2; HR, hazard ratio; PFS, progression-free survival.