Table 2.

Tumor and treatment characteristics by lymph node surgery and pathological node (pN) stage. ER: estrogen receptor. PR: progesterone receptor. HER2: human epidermal growth factor receptor 2. LN: lymph node.

	cN0 without LN Surgery (N=31531)	cN0 + LN Surgery → pN0 (N=85474)	cN0 + LN Surgery → pN1–3 (N=14290)	P-Value
ER Status				†
ER+	28222 (89.5%)	76199 (89.1%)	12674 (88.7%)
ER-	3309 (10.5%)	9275 (10.9%)	1616 (11.3%)
PR Status				0.002
PR+	24209 (76.8%)	65663 (76.8%)	10881 (76.1%)
PR-	7096 (22.5%)	19314 (22.6%)	3335 (23.3%)
HER2 Status*				<0.001
HER2+	1085 (3.4%)	3641 (4.3%)	805 (5.6%)
HER2-	14324 (45.4%)	40968 (47.9%)	6984 (48.9%)
Grade				†
1	10613 (33.7%)	29734 (34.8%)	2971 (20.8%)
2	14687 (46.6%)	39580 (46.3%)	7281 (51%)
3	6231 (19.8%)	16160 (18.9%)	4038 (28.3%)
Clinical T-Stage				†
1	24196 (76.7%)	69681 (81.5%)	8413 (58.9%)
2	6744 (21.4%)	14776 (17.3%)	5185 (36.3%)
3	591 (1.9%)	1017 (1.2%)	692 (4.8%)
Pathologic N-Stage				-
0	8748 (27.7%)	85474 (100%)	0 (0%)
1	0 (0%)	0 (0%)	11810 (82.6%)
2	0 (0%)	0 (0%)	1787 (12.5%)
3	0 (0%)	0 (0%)	693 (4.8%)
X	20509 (65%)	0 (0%)	0 (0%)
Treatment with Chemotherapy	883 (2.8%)	4989 (5.8%)	3165 (22.2%)	<0.001
Treatment with Radiation Therapy	8187 (26%)	40604 (47.5%)	7104 (49.7%)	<0.001
Treatment with Endocrine Therapy
Among All Patients	14646 (46.5%)	49966 (58.5%)	10286 (72%)	<0.001
Among ER+ or PR+ Patients	14499 (51.1%)	49627 (64.7%)	10225 (80.1%)	<0.001
Surgery Type
Lumpectomy	24738 (78.5%)	56549 (66.2%)	6391 (44.7%)
Mastectomy	6793 (21.5%)	28925 (33.8%)	7899 (55.3%)
Surgery + Radiation				<0.001
Mastectomy + Radiation	252 (0.8%)	1226 (1.4%)	2068 (14.5%)
Lumpectomy + Radiation	7935 (25.2%)	39378 (46.1%)	5036 (35.2%)
Mastectomy + No Radiation	6438 (20.4%)	27250 (31.9%)	5733 (40.1%)
Lumpectomy + No Radiation	16351 (51.9%)	16538 (19.3%)	1303 (9.1%)
Radiation duration– Median (IQR)**	43 (26 – 49)	44 (23 – 49)	46 (41 – 50)	<0.001

^†Covariates used in matching.

^*HER2 status has high missingness due to unreliable coding prior to 2010.

^**Reported in days