Table 1.

Patient characteristics

Variables	n	BCS (%)	MAST (%)	P-value
Age (years)				<0.001
<50	8,943	5,148 (22.7)	3,795 (32.3)
≥50	25,504	17,533 (77.3)	7,971 (67.7)
Race/ethnicity				<0.001
Non-Hispanic White	26,417	17,607 (77.6)	8,810 (74.9)
Non-Hispanic Black	2,481	1,617 (7.1)	864 (7.3)
Hispanic (all races)	2,578	1,684 (7.4)	894 (7.6)
Other	2,971	1,773 (7.8)	1,198 (10.2)
Grade				<0.001
Well differentiated	9,400	6,503 (28.7)	2,897 (24.6)
Moderately differentiated	18,510	12,137 (53.5)	6,373 (54.2)
Poorly/undifferentiated	6,537	4,041 (17.8)	2,496 (21.2)
Unknown
Tumor stage				<0.001
T1	27,974	19,131 (84.3)	8,843 (75.2)
T2	6,473	3,550 (15.7)	2,923 (24.8)
PR status				<0.001
Negative	3,485	2,189 (9.7)	1,296 (11.0)
Positive	30,962	20,492 (90.3)	10,470 (89.0)
Chemotherapy				0.002
No/unknown	26,512	17,569 (77.5)	8,943 (76.0)
Yes	7,935	5,112 (22.5)	2,823 (24.0)
21-gene recurrence score				<0.001
Low risk	18,664	12,441 (54.9)	6,223 (52.9)
Intermediate risk	12,693	8,423 (37.1)	4,270 (36.3)
High risk	3,090	1,817 (8.0)	1,273 (10.8)

Abbreviations: MAST, mastectomy; PR, progesterone receptor; T, tumor; BCS, breast-conserving surgery.