A model of immunohistochemical differences between invasive breast cancers and DCIS lesions tested on a consecutive case series of 1248 patients

Table 3 Relative tissue invasion rates according to the Ki-67 value

Binary features			DCIS	IDC	Relative rate	Rate difference (positive–negative)
ER	Negative		16	290	1.0142	−0.0186
	Positive		52	890	0.9955	−0.0186
	Total		68	1180	1.0000
PgR	Negative		29	370	0.9010	0.1577
	Positive		39	810	1.0587	0.1577
	Total		68	1180	1.0000
HER2	Negative		46	857	1.0231	−0.0772
	Positive		22	323	0.9459	−0.0772
	Total		68	1180	1.0000
Ki-67	<=14%		43	451	0.8390	0.3317
	>14		25	729	1.1707	0.3317
	Total		68	1180	1.0000
Ductal breast cancer types including Luminal B1 and proposed other Ki-67 subtypes	Luminal A		34	363	0.8446	0.5489
	Luminal B1		6	340	1.3936	0.5489
	Luminal B2	<=14%	4	54	0.9190	0.0929
	Luminal B2	>14%	8	144	1.0119	0.0929
	HER2	<=14%	4	15	0.5355	0.4824
	HER2	>14%	6	110	1.0179	0.4824
	Triple-negative	<=14%	1	20	1.0463	0.0964
	Triple-negative	>14%	5	134	1.1427	0.0964
	Total		68	1180	1.0000

Because Luminal B1 cancers differ from Luminal A cancers only by Ki-67 values, the same threshold of the 14% Ki-67 value was applied to Luminal B2, HER2-overexpressed and triple-negative cancers. Luminal B1 phenotype was 39% faster than average in progression. The rare combination of low Ki-67 in HER2-overexpressed cancers (14% of HER2 cancers) showed very slow rate of transition to IDC (only 53.55% of the average rate).

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