Multi-points and Full-thickness Biopsy in the Diagnosis of cCR After Neoadjuvant Therapy for Rectal Cancer

Background There is currently no reliable means to restage rectal cancers after neoadjuvant chemoradiation. There are still no reliable methods to identify patients with pCR before radical surgery. As a result, clinical complete response (cCR), defined as no clinical detectable tumor by physical examination, endoscopic evaluation, and imaging, is designed as a surrogate endpoint for pCR. However, the concordance between cCR and pCR varies from 22% to 96% in different reports, which questions the clinical value of such strategies. Therefore, based on rectal diginal examination, serum CEA, MRI, endoscopy examination, we suggested to add multi-points and full-thickness biopsy technique to further improve the accuracy of cCR.