After local excision for early rectal cancer, completion total mesorectal excision can reduce recurrence risk but may also carry considerable morbidity and affect functional outcomes. TESAR investigated whether adjuvant chemoradiotherapy could be used as a rectum-preserving option in this setting.
The original article, titled “Adjuvant chemoradiotherapy versus completion total mesorectal excision after local excision for early rectal cancer (TESAR): a multicentre, randomised, controlled, phase 3, non-inferiority trial,” was published online in The Lancet Gastroenterology & Hepatology on May 27, 2026.
Authors: Laura R Moolenaar, Mahsoem Ali, Theo J Aufenacker, Geerard L Beets, Robbert J I Bosker, Tineke E Buffart, Jacobus W A Burger, Evelien Dekker, Quentin Denost, Pascal G Doornebosch, Peter van Duijvendijk, Hans F J Fabry, Elisabeth D Geijsen, Michael F Gerhards, Wilhelmina M U van Grevenstein, Brechtje A Grotenhuis, Christiaan Hoff, Jeroen W A Leijtens, Koen C M J Peeters, Apollo Pronk, George P van der Schelling, Colin Sietses,
Anke B Smits, Boudewijn R Toorenvliet, Anthony W H van de Ven, Emiel G G Verdaasdonk, Ronald J C L M Vuylsteke, Henderik L van Westreenen, Johannes H W de Wilt, David D E Zimmerman, Marilyne M Lange, Nicole C T van Grieken, Barbara A J Bastiaansen, Roel Hompes, Corrie A Marijnen, Marcel G W Dijkgraaf, Leon M G Moons, Pieter J Tanis, Chris Cunningham, and J B Tuynman, on behalf of the TESAR Study Group.
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Study Design
TESAR was a multicentre, open-label, randomised, controlled, phase 3 non-inferiority trial conducted across 25 hospitals in the Netherlands and France. Eligible patients were aged 18 years or older and had locally excised high-risk pT1 or low-risk pT2 rectal cancer located below the sigmoid takeoff. Patients were randomly assigned 1:1 to receive either adjuvant chemoradiotherapy or completion total mesorectal excision.
Adjuvant chemoradiotherapy consisted of 25 × 1.8 Gy limited to the mesorectum, with oral capecitabine 825 mg/m² twice daily. Randomisation was stratified by age, American Society of Anaesthesiologists classification, type of local excision, pathological tumour stage, and resection margin status.
The primary endpoint was 3-year locoregional recurrence, with a prespecified non-inferiority margin of 7%. Secondary endpoints included unsalvageable locoregional recurrence, disease-free survival, overall survival, treatment-related morbidity within 30 days, stoma rate, and quality of life.
The trial was registered on ClinicalTrials.gov as NCT02371304. On October 1, 2024, it was converted to a patient-preference design because of loss of equipoise before reaching the planned sample size of 302 patients. The current analysis included patients randomly assigned before that transition.
Patient Population
Between November 1, 2015, and September 14, 2024, 202 patients were randomly assigned. Of these, 197 were included in the intention-to-treat analysis: 101 in the adjuvant chemoradiotherapy group and 96 in the completion total mesorectal excision group.
Among included patients, 118 were male and 79 were female. The mean age was 64.7 years, and the mean BMI was 26.5 kg/m². Median follow-up was 50.0 months.
Key Findings
Five locoregional recurrences were reported: four in the adjuvant chemoradiotherapy group and one in the completion total mesorectal excision group.
The estimated 3-year locoregional recurrence rate was 5.0% after adjuvant chemoradiotherapy and 1.1% after completion total mesorectal excision. Adjuvant chemoradiotherapy did not meet the prespecified non-inferiority margin for 3-year locoregional recurrence, with a difference of 3.9% and a one-sided p value for non-inferiority of 0.16. However, four of the five locoregional recurrences were successfully salvaged. The 3-year unsalvageable locoregional recurrence rate was 1.3% after adjuvant chemoradiotherapy and 0.0% after completion total mesorectal excision.
Three-year disease-free survival was 92.0% after adjuvant chemoradiotherapy and 96.3% after completion total mesorectal excision. Three-year overall survival was 98.9% in both groups.
Safety and Morbidity
Treatment-related toxicity occurred in 82 of 105 patients who received adjuvant chemoradiotherapy. Grade 3 or higher toxicity occurred in 10 patients. Post-operative complications occurred in 32 of 73 patients after completion total mesorectal excision. Clavien–Dindo grade IIIa or higher complications occurred in 11 patients.
Three-year stoma rates were significantly lower after adjuvant chemoradiotherapy, at 2.6%, compared with 45.4% after completion total mesorectal excision. Quality-of-life outcomes at 1 year were comparable or favoured adjuvant chemoradiotherapy across nearly all domains.
Takeaway
TESAR did not formally confirm non-inferiority of adjuvant chemoradiotherapy compared with completion total mesorectal excision for 3-year locoregional recurrence. However, because the trial stopped randomisation before reaching its planned sample size, the results should be interpreted in that context. Adjuvant chemoradiotherapy showed low unsalvageable locoregional recurrence, fewer stomas, and lower treatment burden, supporting its consideration as an organ-preserving strategy for selected patients with locally excised high-risk pT1 or low-risk pT2 rectal cancer.
The full article is available in The Lancet Gastroenterology & Hepatology.