Table 2. Patient characteristics.

	Cases n = 115	Controls n = 115
Age at diagnosis, years
Median (range)	48 (22, 83)	48 (24, 88)
Race/ethnicity
Caucasian	66 (57%)	69 (60%)
African-American	25 (22%)	16 (14%)
Asian/Pacific Islanders	5 (4%)	6 (5%)
Hispanic	18 (16%)	23 (20%)
Other	1 (1%)	1 (1%)
Menopausal status at diagnosis
Premenopausal	54 (47%)	58 (51%)
Perimenopausal	4 (3%)	9 (8%)
Postmenopausal	57 (50%)	48 (41%)
Stage at sample collection
I	4 (3%)	4 (3%)
II	49 (43%)	55 (48%)
III	62 (54%)	56 (49%)
Subtype based on ER, PR, HER2
ER/PR+ and HER2−	57 (50%)	58 (50%)
HER2+	19 (16%)	18 (16%)
Triple negative	39 (34%)	39 (34%)
Year of sampling
2003	12 (10%)	8 (7%)
2004	14 (12%)	22 (19%)
2005	23 (20%)	17 (15%)
2006	16 (14%)	14 (12%)
2007	12 (10%)	17 (15%)
2008	27 (23%)	27 (23%)
2009	11 (10%)	10 (9%)
Time to metastases, years
Median (range)	2.3 (0.6, 9.0)	-