Preoperative MRI Assessment of Circumferential Resection Margin Predicts Survival and Local Recurrence in Rectal Cancer
In a study reported in the Journal of Clinical Oncology, Taylor et al evaluated the ability of preoperative high-resolution magnetic resonance imaging (MRI) assessment of circumferential resection margin to predict outcome in patients with rectal cancer. They found that MRI assessment was independently predictive of local recurrence, disease-free survival, and overall survival.
Study Details
The study used data from 374 patients with rectal cancer from the 5-year follow-up of the MERCURY trial. Patients underwent preoperative high-resolution pelvic MRI, with tumor distance to the mesorectal fascia of ≤ 1 mm defined as an MRI-involved circumferential resection margin. Multivariate analysis of preoperative variables included age, sex, type of preoperative treatment, MRI assessment of tumor height, MRI circumferential resection margin status, and MRI-predicted American Joint Committee on Cancer (AJCC) TNM stage.
For pathologic circumferential resection margin involvement (tumor at ≤ 1 mm from radial resection margin), preoperative MRI had a positive predictive value of 53%, negative predictive value of 94%, sensitivity of 64%, specificity of 91%, and accuracy of 87%. The odds ratio for MRI-involvement resulting in pathologic circumferential resection margin involvement was 17.36 (P < .001), and the relative risk for MRI-involved vs MRI-clear findings resulting in pathologic circumferential resection margin involvement was 8.67 (P < .001).
Predictive Ability of MRI Circumferential Resection Margin Status
Median follow-up was 62 months in surviving patients. For MRI-clear vs MRI-involved patients, 5-year overall survival was 62.2% vs 42.2% (hazard ratio [HR] = 1.99, P < .001), 5-year disease-free survival was 67.2% vs 47.3% (HR = 1.96, P < .01), and local recurrence rates were 7.1% vs 20.0% (HR = 3.9, P < .001).
On multivariate analysis, MRI-determined circumferential resection margin involvement remained significantly predictive for overall survival (HR = 1.97, P < .01), disease-free survival (HR = 1.65, P < .05), and local recurrence (HR = 3.50, P < .05), with MRI-based involvement being the sole independent predictor of local recurrence and the only variable independently predictive for overall survival, disease-free survival, and local recurrence. On multivariate analysis, MRI TNM stage III vs I was significantly predictive for disease-free survival (HR = 2.42, P < .05), but not for overall survival (HR = 0.91, 95% confidence interval [CI] = 0.591.40), or local recurrence (HR = 2.08, 95% CI = 0.68–3.67).
The investigators concluded: “High-resolution MRI preoperative assessment of circumferential resection margin status is superior to AJCC TNM-based criteria for assessing risk of [local recurrence], disease-free survival, and overall survival…. [H]igh-resolution MRI circumferential resection margin assessment identifies patients with particularly poor outcomes, which enables teams to specifically direct treatment toward reducing [local recurrence] and improving survival.”
Gina Brown, MBBS, MD, of The Royal Marsden Hospital, Surrey, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by grants from Siemens Medical United Kingdom and Pelican Cancer Foundation for the original MERCURY Study, Croydon Colorectal Cancer Charity, Pelican Cancer Foundation, Yorkshire Cancer Research and Experimental Cancer Medicine Centre, and National Institute for Health Research Specialist Biomedical Research Centre for Cancer. The study authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
