Assessment of tumor budding in colorectal carcinoma : correlation with b-catenin nuclear expression

الملخص EN

Background : Tumor budding (TB) is showing increasing promise as a colorectal cancer (CRC) prognosticator that is independent of TNM staging.

B-Catenin is a component of the Wingless Want signaling pathway that is bound to membrane-associated E-cadherin and is essential for its correct position and function.

Methods : this study was designed to detect TB in 44 resected primary CRC cases and also to compare b-catenin expression in the tumor budding sites (TBS) and in the tumor center.

Tumor budding was assessed in both H&E and pankeratin immunostained sections.

Agreement between TB scoring using pan cytokeratin and H&E was tested.

Also, typing of the tumor margin and determination of degree of cytoplasmic pseudo-fragmentation was done.

Tumor budding, cytoplasmic pseudo fragments and b-catenin expression were related to known CRC prognosticators.

Results : Ten tumors (22.7 %) showed low grade (LG) budding and 34 tumors (77.3 %) showed high grade (HG) budding.

The 34 HG budding tumors were further subdivided into moderate and severe (n = 13, n = 21, respectively) budding cancers.

Twenty nine tumors (65.9 %) showed LG cytoplasmic pseudo fragments and 15 tumors (34.1 %) showed HG pseudo fragments.

Scoring of TB on H & E and pan keratin stained sections revealed moderate agreement (Kappa= .558; p= < .000).

A significant relation between TB and cytoplasmic pseudo fragments was observed (p= .009).

Both TB and cytoplasmic pseudo fragments did not significantly associate with clinic pathologic parameters.

Immunoreactivity of nuclear and cytoplasmic b-catenin was significantly higher at TBS compared to tumor center (p= .005, p= .000, respectively).

In opposition, membranous bcatenin expression was significantly higher in the tumor center than in TBS (p = .001).

Although, nuclear b-catenin accumulation at TBS was noted, yet, it did not relate significantly with both TB and cytoplasmic pseudo fragments around TBS (p = .649; p = .675, respectively).

Also, nuclear b-catenin immunoreactivity did not relate significantly with the various clinic pathological variables.

Conclusion : Pan keratin immunostaining facilitates typing of CRC invasive margin, and determination of the degree of TB and cytoplasmic pseudo-fragmentation.

Catenin expression differs significantly between tumor center and TBS in CRC.

Cut-offs for TB assessment should be unified and further studies are recommended to allow a better understanding of this process before establishing TB as a prognostic factor beyond the TNM staging in CRC.