Table 4.

. Relationship of serum estrogen level and response (a) and change in FFNP uptake after estradiol challenge (b).

(a) Relationship between serum estrogen level and clinical response (n = 37)
	Clinical effect of endocrine therapy
	Response (n = 24) Median (Q1–Q3)a	No response (n = 13) Median (Q1–Q3)		pb
Prior to estradiol challenge
Baseline estradiol level	15.1 (13.4–19.1)	13.3 (8.6–19.3)		0.37
After estradiol challenge
Change of estradiol against baselinec	9.9 (5.8–15.5)	13.2 (10.2–21.8)		0.25

(b) Relationship between serum estradiol level and FFNP uptake change (n = 37)
	FFNP uptake change
	Spearman correlation coefficients			pd
Prior to estradiol-challenge test
Baseline estradiol level	0.25			0.14
After estradiol-challenge test
Change rate of estradiol levelc	−0.23			0.17

^aQ1 = 25^th percentile, Q3 = 75^th percentile.

^bKruskal-Wallis test.

^cCalculated as (estradiol level after estradiol challenge − baseline estradiol level)/baseline estradiol level.

^dSpearman-Brown test.