Pathological Assessment of Rectal Cancer after Neoadjuvant Chemoradiotherapy: Distribution of Residual Cancer Cells and Accuracy of Biopsy.

Lin Xiao,Mengzhong Liu,Yujia Zhu,Wenjing Deng,Hui Chang,Huizhong Zhang,Huixia Feng,Shaoyan Xi,Xin Yu,Weiwei Xiao,Yuanhong Gao

doi:10.1038/srep34923

Abstract

We investigated the distribution of residual cancer cells (RCCs) within different layers of the bowel wall in surgical specimens and the value of biopsies of primary rectal lesion after preoperative volumetric modulated arc therapy (VMAT) with concurrent chemotherapy in patients with rectal cancer. Between April 2011 and April 2013, 178 patients with rectal cancer who received preoperative VMAT, concurrent chemotherapy, and surgery were evaluated; 79 of the patients received a biopsy of the primary lesion after chemoradiotherapy and prior to surgery. The distribution of RCCs in the surgical specimens and the sensitivity and specificity of the biopsy of primary rectal lesions for pathological response were evaluated. Fifty-two patients had a complete pathological response in the bowel wall. Of the 120 patients with ypT2-4, the rate of detection of RCCs in the mucosa, submucosa, and muscularis propria was 20%, 36.7%, 69.2%, respectively. The sensitivity and specificity of biopsies of primary rectal lesions was 12.9% and 94.1%, respectively. After chemoradiotherapy, the RCCs were primarily located in the deeper layers of the bowel wall, and the biopsy results for primary rectal lesions were unreliable due to poor sensitivity.

Highlights

Positron emission tomography/computed tomography (18F- FDG PET/CT) can accurately identify patients with pCR4,13,14
204 consecutive patients with rectal carcinoma were treated with preoperative volumetric modulated arc therapy (VMAT) and concurrent chemotherapy from April 2011 to April 2013 at Sun Yat-sen University Cancer Center
90 cases presented with low-lying rectal cancer, 74 cases presented with middle rectal cancer (5.0 cm < distance to anal verge ≤ 10 cm), and 14 cases presented with high rectal cancer

Summary

Introduction

Positron emission tomography/computed tomography (18F- FDG PET/CT) can accurately identify patients with pCR4,13,14. An understanding of RCCs may improve the consistency of cCR and pCR after neoCRT in patients with mid to low-lying rectal cancer who wish to be treated with a non-surgical approach This understanding may facilitate the exploration of the underlying mechanisms of resistance to chemoradiotherapy. Duldulao MP et al.[20] reported that in rectal cancer specimens of patients treated with preoperative conventional radiation plus concurrent 5-FU-based chemotherapy, RCCs were distributed preferentially in the muscularis propria and subserosa layers. It is not clear whether different radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), could significantly affect the distribution of RCCs in the bowel wall after neoCRT. For 79 patients, we compared the pathology results of the biopsy specimens of primary rectal lesions after chemoradiotherapy and prior to surgery with those of their corresponding surgical specimens

Methods

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Discussion

Conclusion