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Name of the study


Researchers and contact information

Lead investigators:

Professor dr. H.J. Bonjer

Dr. J.B. Tuynman 


Other principal investigators

Prof. dr. G.B. Hanna 
Imperial College London

Prof. dr. A.M. Lacy.
Hospital Clinic

Professor dr. W.A. Bemelman
Amsterdam UMC locatie AMC

Dr. C. Sietses
Ziekenhuis Gelderse Vallei

Dr. R. Hompes
Amsterdam UMC locatie AMC

Trial statistician

Prof. Dr. J.W.R. Twisk
Head dept of epidemiology and biostatistics, Amsterdam UMC location VUmc


TRIAL coördinator

Drs. SE. (Stefan) van Oostendorp 
Amsterdam UMC locatie VUmc

Afdeling Heelkunde, Kamer 7F 20

De Boelelaan 1117, 1081 HV Amsterdam

E: |

Tel: +31 20 4443529

Summary study


The quality of rectal cancer surgery has improved during the last decades with the total mesorectal excision (TME) technique, adaptation of laparoscopic surgery and extralevatory approach for abdominoperineal resection (APR). Nevertheless, surgery for mid and low rectal cancer is associated with relative high rates of conversions, permanent colostomies, and incomplete mesorectal excisions and relative high rates of circumferential resection margin (CRM) involvement resulting in significant number of local recurrences.

The transanal TME (TaTME) has been developed with use of laparoscopic single port platforms to improve the quality of the TME procedure in mid and low rectal cancer. In TaTME, the tumour is distally approached through the anus with laparoscopic instruments. In TaTME, the tumour is distally approached through the anus with laparoscopic instruments. Latest systematic review of cohort studies showed that the TaTME technique is feasible and facilitates difficult resections in the lower pelvis. A low conversion rate and more sphincter saving procedures are reported. Moreover the current data from cohort studies have shown that the TaTME procedure is safe and is associated with less conversions and less morbidity in experienced centers compared with laparoscopic TME.

Primary objective

Before adaptation of the TaTME as standard surgical therapy for mid an low rectal cancer, a well-designed study is essential to demonstrate its efficacy and safety in a multicenter randomized setting. The primary concern is oncological safety in terms of local recurrence rate. Secondary concerns are conversion rate, permanent colostomy rate and safety in terms of pathology, morbidity and functional outcome.    

Study design

The COLOR III trial is an international multicenter randomized study comparing short- and long term outcomes of TaTME and laparoscopic TME for rectal cancer. The design is non-inferiority compared to conventional laparoscopic surgery. The study will include a quality assessment phase before entering the randomization-phase to ensure required competency level and uniformity of the new TaTME technique and the laparoscopic TME. During the trial the clinical data will be reviewed centrally to ensure uniform quality. 

Study population

Patients with histologically proven single mid or distal rectum carcinoma (0 to 10 cm from anal verge) at MRI, eligible for restorative surgery with a curative intent, are included. Patients with a T1 tumor suitable for local excision, T3 tumors with a suspected involved circumferential resection margin and T4 tumors are excluded. 

Primary endpoint

Local recurrence on MRI at 3 years follow-up after TME


Secondary endpoints

Secondary endpoints include sphincter saving procedures, short-term morbidity and mortality, involved circumferential resection margin (CRM), disease-free and overall survival at 3 and 5 years, completeness of mesorectum and quality of life.  

Sample size

1104 patients in total; 669 in the TaTME arm and 335 in the laparoscopic TME arm to demonstrate a comparable local recurrence (LR) rate at 3-years follow-up. Expected LR rate is 5% in the control group, non-inferiority margin of 4% with a power 80% with a one-sided level of significance of 2.5%) 




Control arm
Laparoscopic abdominal TME resection

Experimental arm
Transanal TME resection

Participating centers (Nederland)

Amsterdam UMC, locatie VUmc, dr JB Tuynman

Amsterdam UMC locatie AMC, prof WA Bemelman, dr PJ Tanis, dr R Hompes

Ziekenhuis Gelderse Vallei, dr C Sietses

Spaarne Gasthuis, dr HBAC Stockmann, Dr SJ Oosterling, dr. R Vuylsteke

IJsselland ziekenhuis, Dr EJ de Graaf, dr PG Doornebosch

Deventer ziekenhuis, Dr K Talsma, Dr. R Bosker

Nog niet open:

OLVG Amsterda, dr MF Gerhards

Zorgsaam Zeeuws-Vlaanderen, dr EAL Lagae      


For a full list of all participating centers globally, please visit