Pathologic upstaging after definitive transanal endoscopic surgery for cT1N0M0 rectal cancer: patterns of care and...

Transanal endoscopic surgery (TES) is an organ-preserving option for select patients with clinically T1N0M0 rectal adenocarcinoma that offers potential avoidance of total mesorectal excision (TME). Preoperative staging is imperfect at distinguishing tumor stage and assessing nodal status, leaving the potential for pathologic upstaging after surgery. Oncologic implications for upstaged individuals who do not undergo completion TME are poorly characterized. This study aims to quantify pathologic upstaging among patients who receive definitive TES, identify associated clinicopathologic factors, evaluate overall survival, and compare outcomes between upstaged TES versus TME patients.

National Cancer Database (2010-2022) was used to identify cT1N0M0 rectal adenocarcinoma patients who underwent TES. Patients who received neoadjuvant therapy were excluded. Upstaging was defined as ≥ pT2 and/or ≥ pN1. A sub-analysis was conducted comparing upstaged patients for whom TES was the definitive procedure versus upstaged patients who underwent TME. Multivariable logistic regression identified associations with upstaging; Cox regression assessed overall survival.

Of 1,175 cT1N0M0 patients who underwent TES, 101 (8.6%) were upstaged, predominately via tumor upstaging (86.1%). Worse tumor differentiation (OR 2.15; CI 1.06-4.35) and larger tumors (> 3 cm OR 7.55; CI 3.24-17.58) were associated with upstaging. Among patients upstaged after TES, 38.6% received adjuvant therapy, with poorer tumor differentiation as the only factor differing from those who did not receive it. Upstaged patients had higher mortality than non-upstaged patients (HR 1.50; 95% CI 1.01-2.22). Compared to 2,350 upstaged cT1N0M0 patients who underwent TME, TES-only patients tended to be older, male, have smaller tumors and worse survival than TME patients (HR 1.54; 95% CI 1.07-2.22; p = 0.02).

8.6% of patients who undergo TES-alone for cT1N0M0 rectal cancer were upstaged and experienced worse survival than appropriately-staged TES and upstaged TME patients. Careful patient selection, completion TME counseling, and improved staging accuracy have the potential to improve outcomes.