Table 3.

The immunostaining of CK7⁺/CDX2⁺ in primary PEACs and CRACs

	No. of cases	CK7+/CDX2+	Non-(CK7+/CDX2+)
Primary PEACs	129	92 (71.3%)	37 (29%)
CRACs	50	9 (18%)	41 (82%)

The expression of CK7 and CDX2 was analyzed in 129 cases of primary PEAC and 50 cases of colorectal carcinoma. The consistently positive expression of CK7 and CDX2 acquired high sensitivity (71.3, 95% CI 63.5–79.1%) and specificity (82, 95% CI 71.4–92.6%) in the differential diagnosis of primary PEAC from CRACs. ROC analysis also suggested well diagnostic value of CK7⁺/CDX2⁺ on primary PEACs (area, 0.767, 95% CI 0.689–0.844, P < 0.01)