Table 2.

Distribution of estrogen receptor (ER), progesterone receptor (PR), and Ki‐67 expression according to the case‐control status

	Total (N = 258)		Case (N = 86)		Control (N = 172)		P‐valueb
	N	%	N	%	N	%
ER expression
≤70%	80	31.0	18	20.9	62	36.1	0.04
71–90%	98	38.0	35	40.7	63	36.6
>90%	80	31.0	33	38.4	47	27.3
PR expression
≤40%	83	32.2	23	26.7	60	34.9	0.02
41–80%	83	32.2	22	25.6	61	35.5
>80%	92	35.7	41	47.7	51	29.7
Proliferative disease	Total (N = 90)		Case (N = 30)		Control (N = 60)
Ki67 expressiona
0% to <1%	26	28.3	8	26.7	18	30.0	0.74
≥1%	64	71.7	22	73.3	42	70.0

^aKi67 expression was evaluated only for proliferative disease.

^bChi‐squared test comparing distributions of characteristics across case‐control status.