A new practical classification of desmoplastic reaction in endoscopic forceps biopsy of colorectal cancer.

BACKGROUND The histopathological discrepancy between endoscopic forceps biopsy (EFB) and post-resection specimens is considered a practical clinical problem. This retrospective study aimed to determine the current diagnostic concordance between the EFB and surgical specimens of colorectal cancer (CRC) and then investigated the useful factors in EFB diagnosis. METHODS We used the representative pathological data of 2188 CRCs. The comparison of histopathological discrepancy between EFB and the related surgical specimens was performed. Furthermore, 418 biopsy specimen slides in our hospital were reviewed to determine the classification of intratumor desmoplastic reaction (DR). RESULTS Among the 2188 patients, the positive sensitivity of EFB for adenocarcinoma was 82.7%. The discrepancy rate between the EFB and surgical specimens was 10.8-40.0% corresponding to different T stages. On the basis of DR classification, 32, 131, and 255 tumors were categorized as little, moderate and extensive, respectively. The correlation between DR classification and tumor invasion based on T stage was significant (Spearman's rho=0.112; p<0.05). The extensive DR provided better estimates for advanced tumors than the little and moderate DR (χ2=3.977, p=0.046). Besides DR, factors including deeper cutting the slides and histological types were significantly associated with "adenocarcinoma" diagnosis in EFB of CRCs (p<0.05). CONCLUSION To the best of our knowledge, this is the first time that a DR classification specifically for EFB specimens was proposed. It might contribute to improve the accuracy of biopsy-based diagnosis of CRC.