COLOR III Short-Term Outcomes for TaTME Versus LapTME

Key Takeaways

• TaTME was associated with a lower need for conversion than LapTME in this randomized comparison.
• Ninety-day morbidity and anastomotic leakage were reported at similar levels across the two surgical groups.
• Specimen quality and margin involvement were comparable, while functional and oncologic follow-up remains in progress.

Short-term secondary outcomes from the COLOR III trial showed lower conversion with transanal total mesorectal excision than with laparoscopic total mesorectal excision in mid and low rectal cancer. Conversion occurred in 4 of 696 patients (1%) with TaTME and 56 of 339 (17%) with LapTME, for an adjusted odds ratio of 0.03. The dataset centers on perioperative and pathologic measures rather than long-term cancer control outcomes. Follow-up for the primary endpoint of 3-year local recurrence is still underway. These findings provide an early view of surgical outcomes rather than the trial's final oncologic results.

COLOR III was an international, multicenter, open-label, phase 3 randomized controlled non-inferiority trial conducted at 28 hospitals. Eligible patients were adults aged 18 years or older with (y)cT1-3N0-2M0 rectal adenocarcinoma located 10 cm or less from the anal verge. Randomization used an interactive web-response system and assigned patients in a 2:1 ratio to TaTME or LapTME. The primary endpoint is 3-year local recurrence, assessed for non-inferiority, and the short-term secondary endpoints reported here were conversion, 90-day morbidity, anastomotic leakage, specimen quality, and CRM and DRM involvement. Investigators randomized 1103 patients between Jan 2, 2017, and Jan 16, 2024; analyses used a modified intention-to-treat approach, and quality assurance included pre-trial video-based competency assessment and central MRI evaluation for patient eligibility. Recruitment has been completed while follow-up continues.

Postoperative complications within 90 days occurred in 138 of 689 patients (20%) after TaTME and 59 of 335 (18%) after LapTME, with an adjusted odds ratio of 1.22. Anastomotic leakage occurred in 68 of 689 patients (10%) and 27 of 333 (8%), respectively, with an adjusted odds ratio of 1.32. Minor morbidity affected 61 of 689 patients (9%) versus 26 of 333 (8%), and major morbidity affected 77 of 689 (11%) versus 31 of 333 (9%). The adjusted odds ratio for major morbidity was 1.23, and confidence intervals for complications, major morbidity, and leakage crossed unity. Overall, perioperative morbidity patterns were broadly similar across the two approaches during 90-day follow-up.

Macroscopically complete resection was achieved in 583 of 692 TaTME specimens (84%) and 291 of 339 LapTME specimens (86%). Positive circumferential resection margins were uncommon, occurring in 4 of 611 TaTME procedures and 1 of 291 LapTME procedures. Positive distal resection margins were also rare, reported in 7 of 690 procedures and 1 of 334 procedures, respectively. The investigators described TaTME as a safe technique for mid and low rectal cancer, with lower conversion and similar 90-day morbidity and complete resection rates compared with LapTME. Functional outcomes, oncologic outcomes, and the primary endpoint of 3-year local recurrence require ongoing follow-up.