Table 1.

Patient characteristics, tumour characteristics and treatment

	HER2 negative		HER-2 2+		HER-2 3+		p for difference**
	(N = 1326)		(N = 269)		(N = 103)
	N	%	N	%	N	%
Age in years (mean, SD)	76.1 (7.2)		76.0 (7.2)		75.0 (6.9)		0.272
Number of comorbidities							0.481
0–1	627	47.3	586	44.2	113	8.5
2–4	586	44.2	114	42.4	28	10.4
5 or more	113	8.5	39	37.9	13	12.6
TNM stage							0.050
I	478	36.0	87	32.3	21	20.4
II	671	50.6	138	51.3	66	64.1
III	145	10.9	36	13.4	14	13.6
Missing	32	2.4	8	3.0	2	1.9
Grade							<0.001
1	184	13.9	27	10.0	4	3.9
2	422	31.8	87	32.3	16	15.5
3	316	23.8	90	33.5	62	60.2
Missing	404	30.5	65	24.2	21	20.4
Morphology							0.001
Ductal	969	73.1	218	81.0	91	88.3
Lobular	157	11.8	18	6.7	4	3.9
Other/missing	200	15.1	33	12.3	8	7.8
ER/PR							<0.001
Negative	180	13.6	33	12.3	54	52.4
Positive	980	73.9	209	77.7	35	34.0
Missing	166	12.5	27	10.0	14	13.6
Ki-67							<0.001
Negative	1094	82.5	228	84.8	75	72.8
Positive	84	6.3	20	7.4	21	20.4
Missing	148	11.2	21	7.8	7	6.8
Breast surgery*							0.007
BCS	510	38.5	95	35.3	24	23.3
Mastectomy	816	61.5	174	64.7	79	76.7
Axillary surgery*							0.296
No axillary surgery	181	13.7	35	13.0	16	15.5
Sentinel node	311	23.5	71	26.4	16	15.5
ALND	834	62.9	163	60.6	71	68.9
Adjuvant radiotherapy							0.947
No	686	51.7	142	52.8	54	52.4
Yes	640	48.3	127	47.2	49	47.6
Adjuvant endocrine therapy							0.008
No	728	54.9	127	47.2	66	64.1
Yes	598	45.1	142	52.8	37	35.9
Adjuvant chemotherapy							0.003
No	1250	94.3	257	95.5	89	86.4
Yes	76	5.7	12	4.5	14	13.6

BCS Breast-conserving surgery, ALND axillary lymph node dissection

* The most extended therapy was taken into account

** p values are calculated by the Pearson Chi-Square for categorical variables, and with an oneway ANOVA test for continuous variables. p values in bold font indicate a statistically significant difference between the groups at the p level of <0.05