MUC1, CK20, and CDX2 immunohistochemical markers can sub-classify periampullary carcinomas into pancreaticobiliary, intestinal, and mixed subtypes

Introduction: Pancreaticobiliary subtype of Periampullary carcinoma (PAC) has a poor prognosis in comparison to the intestinal subtype. We assessed the potential of cytokeratins and mucin markers to classify the sub-types of periampullary tumors and compared them with the survival data to identify markers that may predict prognosis.

Methodology: PAC tumor tissues were obtained from 94 patients undergoing Whipples Pancreaticoduodenectomy. Paraffin-embedded tissues were immunostained with cytokeratins CK7, CK20), mucins (MUC1, MUC2, MUC5Ac), and CDX2 antibodies. The survival status of patients was obtained as follow-up up to 5-years of surgery. The Receiver Operating Character Curve (ROC) analysis was used for detecting sensitivity and specificity. The survival data were analyzed using the Kaplan-Meier survival curve.

Results: Tumors were initially categorized on the basis of histological classification as pancreaticobiliary (n = 46), intestinal (n = 35) and indeterminate (n = 13). Further, using immunohistochemical markers (MUC1, CK20, and CDX2), we gave systematic classification of IHC-PB (n = 51), IHC-Int (n = 30) and IHC-Mixed (n = 13). The interobserver analysis showed good agreement between histologic and IHC type with a kappa value of 0.554. Combined expression of CK20, MUC1 and CDX2 accurately classify the mixed type of tumor. Overall survival rate and duration were 74.4% and 44.95 ± 2.29 months. Survival analysis for subtypes reveal, pancreaticobiliary tumors have low survival (27.9 ± 1.63 months) than mixed type (35.5 ± 0.45 months) and intestinal-type (52.92 ± 2.18 months). Among these, intestinal-type have better survival. Only TNM Stage III (tumor staging as per American Joint Committee on Cancer classification) and perineural invasion have been associated with predicting poor survival in PAC patients.

Conclusion: Our results suggest that the combined expression of MUC1, CK20 and CDX2 could serve as markers to diagnose histological inconclusive specimens as mixed subtype tumors.