Table 1.

Clinical and pathological features of MDLs as compared with a sporadic breast cancer cohort

	MDL (n = 82)	IDC (n = 256)		ILC (n = 64)
Clinicopathological feature	n (%)	n (%)	P value	n (%)	P value
Age at diagnosis (years)			0.3238a		0.0083a
Average	57	58		62
Range	28–86	27–88		40–85
Median	55	58		63
Tumour size (cm)			0.2929		0.2017
<2	33 (42.9)	108 (42.2)		21 (34.4)
2–5	33 (42.9)	92 (35.9)		24 (39.3)
>5	11 (14.3)	56 (21.9)		16 (26.2)
Not reported	5	–		3
Total	82	256		64
Tumour gradeb			0.0254		0.0006
1	9 (11.0)	40 (15.6)		2 (3.1)
2	48 (58.5)	106 (41.4)		56 (87.5)
3	25 (30.5)	110 (43.0)		6 (9.4)
Lymph node status			0.0033b		0.0097b
Positive	41 (68.3)	65 (41.1)		14 (40.0)
Negative	19 (31.7)	79 (54.9)		21 (60.0)
Not reported	22	112		29
Total	82	256		64
In situ lesions			<0.0001		<0.000
DCIS only	35 (60.3)	119 (100)		0 (0)
LCIS only	7 (12.1)	0 (0)		29 (93.5)
DCIS + LCIS	16 (27.6)	0		2 (6.5)
Not reported	24	137		33
ER			0.0102b		0.7842b
Positive	72 (90.0)	192 (76.8)		53 (91.4)
Negative	8 (10.0)	58 (23.3)		5 (8.6)
Not reported	2	6		6
Total	82	256		64
PR			0.0003b		0.0651b
Positive	67 (83.8)	154 (62.1)		38 (70.4)
Negative	13 (16.3)	94 (37.9)		16 (29.6)
Not reported	2	8		10
Total	82	256		64
HER2 (IHC)			1.0b		0.1255b
Positive	14 (18.2)	45 (18.7)		4 (8.0)
Negative	63 (81.8)	196 (81.3)		46 (92.0)
Not reported	5	15		14
Total	82	256		64
HER2 (ISH)			0.2181b		0.0196b
Positive	8 (17.8)	27 (11.2)		2 (3.4)
Negative	37 (82.2)	215 (88.8)		56 (96.6)
Total	45	242		58

ISH, in situ hybridization.

Chi‐square test unless indicated.

A P value of <0.05 is considered to be significant.

^a t‐test.

^bFisher's exact test.