AB151. 85. Comparative oncological outcomes of upper third rectal cancer: a meta-analysis

Background: The implementation of preoperative chemoradiation combined with total mesorectal excision has reduced local recurrence rates in rectal cancer. However, the use of neoadjuvant treatment in upper third rectal cancer is controversial. The current study aimed to use meta-analytical techniques to compare outcomes of upper third rectal tumors relative to those of the more distal rectum.

Methods: Meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Databases were searched for studies comparing outcomes between upper third and more distal rectal cancer patients undergoing primary resection, without neoadjuvant treatment for upper third tumours. Upper third tumours were defined as tumours located from 10–15 cm from the anal verge. Results were reported as odds ratios (OR) with 95% confidence intervals (CI).

Results: A total of 174 citations were reviewed; 5 studies comprising of 3,969 patients were ultimately included in the analysis. There was no difference in the rate of T3/4 tumors (OR: 1.366; 95% CI: 0.989–1.887; P=0.058), lymph node positivity (OR: 1.024; 95% CI: 0.884–1.187; P=0.750) and circumferential resection margin (CRM) positivity (OR: 0.778; 95% CI: 0.479–1.264; P=0.311) between upper third and more distal rectal cancers. However local recurrence (OR: 0.519; 95% CI: 0.318–0.846; P=0.009) and distant recurrence (OR: 0.601; 95% CI: 0.500–0.723; P<0.001) were reduced in patients with upper third rectal cancer.

Conclusions: These data suggest upper third rectal cancer represents a biologically more inert disease phenotype than more distal tumors. Further studies on the benefit of neoadjuvant chemoradiotherapy in this cohort are required.

Keywords: Rectal; cancer; location; outcome