Table 1.

The patient clinicopathological data.

	BCVY		Old BC		P value
	NUM.	%	N°	%
Age BCVY/old BC
<25 years/46-50 years	12	4.7	6	5.9
25-30 years/50-56 years	60	23.2	55	54.4
30-35 years/>65 years	186	72.1	40	39.6
Year of diagnosis
Before 2000	60	23	50	49.5	.642
After 2000	198	77	51	50.5
Tumor size
<2 cm	94	36.4	67	66.3	3.01 × 10−3
2-5 cm	112	43.4	29	28.7
>5 cm	35	13.6	5	5
Missing	17	6.6	0	0
Lymph node status
Node positive	121	46.9	38	37.6	.099
Node negative	120	46.5	59	58.4
Missing	17	6.5	4	4
Grade
I	28	11	18	17.8	.583
II	71	27.5	39	38.6
III	94	36.4	39	38.6
Missing	65	25.2	5	5
Histologic subtype
Ductal	209	81	73	72.3	.081
Lobular	10	4	7	6.9
Medullary	8	3	0	0
Tubular	6	2	4	4
Others	25	10	17	16.8
Estrogen receptor
Positive	180	70	72	71.3	.496
Negative	62	24	29	28.7
Missing	16	6	0	0
Progesterone receptor
Positive	153	59.3	69	68.3	.319
Negative	87	33.7	32	31.7
Missing	18	7	0	0
Ki 67 (%)
Low <14	20	7.7	18	17.8	.202
14-30	46	17.8	32	31.6
High >30	41	15.8	16	15.8
Missing	151a	58.5	35	34.6
Her2
Positive	73	28.3	23	22.8	.112
Negative	138	53.5	71	70.3
Missing	47b	18.2	7	6.9
Subtypes
Luminal	131	50.7	62	61.4	.651
Luminal-Her2	46	17.8	17	16.8
Her2 positive	26	10	5	5
Triple negative	35	13.5	17	16.8
Missing	20	7.5	0	0

Abbreviations: BC, breast cancer; BCVY, breast cancer in very young women.

Total number of patients: 258 BCVY and 101 old BC.

^aThe data of Ki 67 were started to be used routinely in the year 2008. Previously lacking these data.

^bThe data of HER2 overexpression are missing because the diagnosis is prior to the knowledge of the role of HER2 in breast cancer.

P values were obtained after a Pearson’s chi-squared test by R/Bioconductor.