Diagnostic precision of magnetic resonance imaging for preoperative prediction of the circumferential margin involvement in patients with rectal cancer.

OBJECTIVE: Circumferential margin involvement (CMI) is an important prognostic indicator for patients with rectal cancer. This meta-analysis aims at evaluating the diagnostic precision of magnetic resonance imaging (MRI) for the preoperative evaluation of CMI in patients with rectal cancer.
METHOD: Quantitative meta-analysis was performed comparing MRI against histology after total mesorectal excision. Sensitivity, specificity and diagnostic odds ratio (DOR) were calculated for each study. Summary receiver operating characteristic (SROC) curves and subgroup analysis were undertaken. Study quality and heterogeneity were evaluated. Meta-regression meta-analysis was used to evaluate the significance of the difference in relative DORs.
RESULTS: Nine studies evaluating 529 patients were included. Pooled results showed an overall sensitivity and specificity for MRI detecting CMI preoperatively of 94% and 85% respectively. The SROC analysis demonstrated an overall weighted area under the curve (AUC) of 0.92 (DOR 57.21, 95% CI 18.21-179.77), without significant heterogeneity between the studies (Q-value 14.66, P = 0.06). Good study quality further increased the sensitivity and specificity of MRI. The use of a 1.5 Tesla coil, a phased array coil and the inclusion of two interpreters also resulted in high preoperative diagnostic precision. Meta-regression meta-analysis showed a significant difference in the DOR for studies published in or since 2003 (P = 0.019).
CONCLUSION: Magnetic resonance imaging can accurately predict CMI preoperatively for rectal cancer in single units and this is reproducible across different centres. This strategy has important implications for selection of patients for adjuvant therapy prior to surgery.