Tumor phenotype and breast density in distinct categories of interval cancer: results of population-based mammography screening in Spain

Breast Cancer Research

Table 2 Biomarker expression among screening-detected cancers (n = 1,297) and distinct categories of interval cancers (n = 948)

	Screening-detected cancers	True interval cancers	False negatives	Minimal-sign cancers	Occult tumors
	n = 1,297	n = 455	n = 224	n = 166	n = 103	P-value^†
Estrogen receptor	1022 (82.5)*	283 (63.2 )*	178 (81.7)	114 (71.3)	84 (88.4)	<0.001
Missing values	58	7	6	6	8
Progesterone receptor	775 (63.7)*	214 (48.2)*	128 (59.0)	86 (54.4)	60 (64.5)	<0.001
Missing values	81	11	7	8	10
HER2	203 (21.9)	113 (29.1)*	44 (24.0)	31 (23.1)	11 (14.1)	0.018
Missing values	371	67	41	32	25
p53	149 (22.7)	86 (36.6)*	23 (21.5)	27 (34.6)	17 (28.8)	<0.001
Missing values	641	228	117	88	44
Ki67	381 (40.2)	169 (52.5 )*	83 (50.3)	50 (41.7)	26 (39.4)	0.001
Missing values	349	133	59	46	37

Number of cases and percentage of tumors with positive biomarker expression. *Standardized Pearson residuals with statistically significant deviation between observed and expected values. ^†P-values for comparison of characteristics among the five study groups were obtained by two-sided Chi-square test. HER2, human epidermal growth factor receptor 2.