MRI helps predict risk of local recurrence in upper rectal cancers

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1. Patients with mesorectal invasion of more than 5mm and sacral-side involvement (seen on MRI) demonstrated higher rates of local recurrence.  

Evidence Rating Level: 2 (Good) 

Study Rundown: Upper rectal cancers (URC), when compared to middle and lower rectal cancers, have a lower risk of local recurrence. This is because URCs are located above the peritoneal reflection, allowing for clear circumferential resection. That being said, the incidence of URC recurrence may be further reduced with the use of preoperative radiotherapy (RT). This study aimed to use MRI to identify URCs that pose the largest threat of recurrence. MRI can detect the proximity of the tumor to the anal verge as well as its distance from the peritoneal reflection. The investigators demonstrated that URCs identified as high risk by MRI were more likely to recur when compared with those identified as intermediate or moderate risk. More specifically, they demonstrated that tumors located on the sacral side with mesorectal invasion greater than 5mm were at an increased risk for local recurrence. These findings suggest that high risk URCs may require additional treatment modalities – perhaps including preoperative radiotherapy. This study paves the way for future investigations on the efficacy of RT in the treatment high risk URC.

Click to read the study in Annals of Surgery

Relevant Reading: Use of surgical procedures and adjuvant therapy in rectal cancer treatment

In-Depth [prospective cohort]: This study used MRI to identify URCs that were at high risk for the study’s primary endpoint, local recurrence. The investigators examined 110 cases of URC and stratified them into 3 groups: intermediate, moderate, and high risk. This stratification was defined using Gunderson’s risk group classification. The anatomical location and mesorectal infiltration was noted for tumors in each of the groups. Though the overall number of cases with local recurrence was low, there was a difference in incidence of recurrence between risk groups. The rates of recurrence in the intermediate, moderate, and high risk groups with sacral-side location were 3%, 4.8%, and 8.7%, respectively. When combined with extensive mesorectal infiltration, the rates were 11.1%, 33.3%, and 18.2%, respectively. Multivariate analyses showed a significant rate of recurrence (p > .05) in tumors with mesorectal infiltration of over 5mm and location on the sacral side. The authors did not compare this sample of patients with another that received preoperative RT – such a study could provide useful information about the management of high risk URCs.

By Amir Tarsha and Chaz Carrier

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