Colorectal cancer is the third most common form and the second leading cause of death among cancers in the Western world. Curative resection is possible if the tumor is accurately assessed before surgery and completely removed.

Managing rectal cancer is challenging for surgeons; optimal management requires detailed, multidisciplinary preoperative planning that includes assessment of the relation of the tumor to surrounding tissues. The presence of tumor within 1 mm of the edges of the area to be surgically excised is an independent predictor of local recurrence and strongly influences decisions about preoperative treatment, such as radio- and chemoradiotherapy.

Between January 2002 and October 2003, a multidisciplinary team from 12 colorectal units in four European countries, led by Dr. Gina Brown of Royal Marsden Hospital in Surrey, UK, conducted an observational study of 408 patients with all stages of rectal cancer to assess the diagnostic accuracy of MRI in predicting the condition of tumor within 1 mm of the resection area.

Before resection, surgeons assessed the tumors with digital rectal examination and sigmoidoscopy, a type of endoscopy, and patients underwent high-resolution MRI scans of the pelvis. The radiologists reported on the scans before surgery and were blinded to the findings of the histopathological assessment of the specimens removed during surgery. As reported in the British Medical Journal, published online Sept. 19, 2006, MRI imaging of rectal cancer predicted curative resection with an accuracy of 88 percent. Specificity for prediction of a clear resection margin by MRI was 92 percent.

The researchers concluded that this data firmly establishes MRI as the modality of choice for preoperative staging prior to surgery. MRI imaging can warn the treatment team of potential failure of surgery, thus aiding decision-making about preoperative treatments and minimizing cancer recurrence.