Table 4. Immunohistochemical analysis of (a) IMP2 and (b) MCM2 expression in HGSCs and ECs.

	HGSC		EC
Organ	High	Low	High	Low	P-value
(a) IMP2
Ovary	39 (89%)	5 (11%)	2 (11%)	16 (89%)	<0.01
Endometrium	23 (79%)	6 (21%)	2 (15%)	11 (85%)	<0.01
Total	62 (85%)	11 (15%)	4 (13%)	27 (87%)	<0.01
				(Fisher's exact test)
(b) MCM2
Ovary	38 (86%)	6 (14%)	3 (17%)	15 (83%)	<0.01
Endometrium	24 (83%)	5 (17%)	1 (8%)	12 (92%)	<0.01
Total	62 (85%)	11 (15%)	4 (13%)	27 (87%)	<0.01
				(Fisher's exact test)

Abbreviations: EC=grade 1 endometrioid carcinoma; HGSC=high-grade serous carcinoma; IMP2= insulin-like growth factor 2 mRNA-binding protein 2; MCM2=DNA replication licensing factor minichromosome maintenance protein 2.

IHC staining of IMP2 and MCM2 in tissue sections revealed significantly more intense IMP2 and MCM2 staining in HGSCs as compared with ECs (P<0.01).

Immunohistochemical (IHC) scoring was performed according to the intensity and distribution of positive staining. Slides were scored as follows: 0+, no cells stained; 1+, pale staining observed in any cells; 2+, deeply stained cells covering <25% of the total area; 3+, deeply stained cells covering 25%–49% of the total area; or 4+, deeply stained cells covering >50% of the total area. Samples were divided into the low expression group (samples with scores of 0+, 1+ and 2+) or the high expression group (scores of 3+ and 4+).