Is tumour location a dominant risk factor of recurrence in early rectal cancer?

Background
Impact of rectal tumour location on risk of lymph node metastases (LNM) and recurrence in early RC is poorly studied and elusive. Tumour location as a prognostic factor may contribute to optimise management of early RC in the future. The aim of this study was to investigate rectal tumour location as an independent predictor of oncologic outcome in early rectal cancer (RC).

Methods
Retrospective multicentre national cohort study on prospectively collected data on all patients with T1-T2 RC, undergoing surgical resection between 2009 and 2021. Tumour location was categorised as distal (0–5 cm), mid (5–10 cm), and proximal (10–16 cm), measured from the anal verge.

Results
Incidence of LNM in the 2424 included T1–T2 RC patients was 18.2%, 17.3% and 21.6% for distal, mid and proximal tumours, respectively. Recurrence was detected in 130 (7.6%) out of 1705 patients available for recurrence analyses (60-month median follow-up). Incidence of recurrence was twice as high in distal (11.4%) compared to proximal (5.6%) tumours and was 8.3% in mid located tumours. Distal (HR 2.051, CI 1.248–3.371, P < 0.05) and mid (HR 1.592, CI 1.061–2.388, P < 0.05) tumour location were significant risk factors of recurrence in uni- and multivariate Cox regression analyses.

Conclusions
This study shows that tumour location significantly affects incidence of recurrence in early RC, with an increasing risk for mid and especially distal location, found to be a predominant risk factor of recurrence. Our findings stress the need for an increased awareness on differences in oncologic outcome related to tumour location in early RC.