Comparative Oncologic Outcomes of Upper Third Rectal Cancers: A Meta-analysis

Preoperative radiation combined with mesorectal excision has reduced local recurrence rates in rectal cancer. The role for neoadjuvant therapy in upper third rectal cancer remains unclear. The current study aimed to use meta-analytical techniques to compare outcomes of upper third rectal tumors relative to those of the middle and lower rectum.

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 patients with upper third and more distal rectal cancer undergoing primary resection. Patients receiving neoadjuvant treatment were excluded. Results were reported as odds ratios (ORs) with 95% confidence intervals (95% CIs).

A total of 174 citations were reviewed; 5 studies comprising 3381 patients were included in the analysis. There was no difference in the rate of T3/4 tumors (OR, 1.303; 95% CI, 0.920-1.847; P = .137), lymph node positivity (OR, 1.004; 95% CI, 0.865-1.165; P = .961), and circumferential resection margin positivity (OR, 0.898; 95% CI, 0.556-1.450; P = .660) between upper third and more distal rectal cancers. However local recurrence (OR, 0.495; 95% CI, 0.302-0.811; P = .005) and distant recurrence (OR, 0.613; 95% CI, 0.511-0.734; P < .001) were reduced in patients with upper third rectal cancer.

These data suggest that upper third rectal cancer has reduced local and distant recurrence rates despite similarity in disease stage and margin positivity. Further studies examining effects of neoadjuvant radiation in rectal cancer should consider upper rectal tumors as a distinct entity to middle and lower rectal tumors.