Optical Biopsy for Distal Margin in Low Rectal Cancer

A Multicenter Randomized Study of Real-time In-vivo Confocal Laser Endomicroscopy Optical Biopsy for Distal Margin in Low Rectal Cancer Compared to Intraoperative Frozen Section

This is a multi-center prospective randomized controlled study. In this study, the investigators will use confocal laser endomicroscopy to make real-time in vivo optical biopsy of distal margin in rectal cancer surgery and help surgeons to make surgical decision.The investigators also assess the accuracy of CLE optical biopsy, compared with intra-operative frozen section.

In low rectal cancer surgery, how to select the precise dissection plane and optimal surgical procedure is an important challenge for surgeons. In current clinic, surgeons select dissection plane by a comprehensive judgment of pre-operative pelvis MRI, colonoscopy and digital rectal examination, then through submitting the "doughnut" after cutting and anastomosis to intra-operative frozen section (IFS) to definite whether there is residual tumor in distal margin (DM). However, IFS can only make diagnosis using the tissue specimen in vitro and time-consuming. Once the IFS confirm positive margin, it always means anal resection should be implemented to ensure radical treatment. Therefore, if there is a real-time in situ examination method to evaluate DM in vivo, it will bring great benefits to both surgeons and patients. Confocal laser endomicroscopy (CLE) had been widely used in medical field to diagnose colorectal disease, but it is seldom applied in surgical filed especially in rectal cancer to make optical biopsy and help surgical decision-making. Therefore, the investigators hypothesize that CLE can real-time in situ evaluate DM during surgery in rectal cancer and its accuracy is non-inferior to intra-operative frozen section. In this study, the investigators will randomly assign patients to the experimental group (CLE optical biopsy) and control group (IFS). Using H-E staining pathological diagnosis as golden standard, the accuracy, sensitivity and specificity of both CLE optical biopsy and IFS will be evaluated and compared. And the investigators will also evaluate patients' postoperative urinary function, defection function and quality of life through a year follow-up.

Confocal laser endomicroscopy optical biopsy will be performed in surgery for patients assigned to this group

In the pCLE group, after intravenous injection of fluorescein, the optical biopsy will be performed, using a confocal miniprobe, to exam the rectal mucosa when the rectum transection is ready. The raters will analyse the CLE images to determine whether the distal margin is positive. In the IFS group, intra-operative frozen section will be performed at the site of distal margin after the rectum transection.

In the pCLE group, after intravenous injection of fluorescein, the optical biopsy will be performed, using a confocal miniprobe, to exam the rectal mucosa when the rectum transection is ready. The raters will analyse the CLE images to determine whether the distal margin is positive. In the IFS group, intra-operative frozen section will be performed at the site of distal margin after the rectum transection.

Accuracy of confocal laser endomicroscopy optical biopsy of distal margin is determined by the pathology result.

Sensitivity and specificity of confocal laser endomicroscopy optical biopsy of distal margin are determined by the pathology result.

Inclusion Criteria: Ages from 18 to 70 years. Rectal tumor confirmed pathologically by endoscopic biopsy. The distance from lower edge of tumor to the dentate line is less than 5cm. Plan to perform curative resection. ASA(American Society of Anesthesiology)score class I,II,or III. Able to provide written informed consent. Exclusion Criteria: Intestinal perforation or acute intestinal obstruction. Multiple distant metastasis and can not R0 resection. T4b according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual Seventh Edition. Pregnancy or breastfeeding. Impaired renal function American Society of Anesthesiology score (ASA) class IV or V. Unable or refuse to provide written informed consent.

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