Abstract
BACKGROUND: Recently, two nonrandomized, prospective cohort studies used magnetic resonance imaging (MRI) to assess the circumferential resection margin to identify "good prognosis" rectal tumors eligible for primary surgery and have reported favorable outcomes. OBJECTIVE: The objective of this project was to conduct a Phase II trial to assess the safety and feasibility of MRI criteria to identify "good prognosis" rectal tumors eligible for primary surgery in the North American setting. METHODS: Patients with newly diagnosed primary rectal cancer attending surgical clinics at participating centers will be invited to participate in the study. The inclusion criteria for the study are: (1) diagnosis of rectal cancer (0-15 cm) from the anal verge on endoscopy and proximal extent of tumor at or below the sacral promontory on computed tomography (CT) or MRI; (2) meets all MRI criteria for "good prognosis" rectal tumor as defined by the study protocol; (3) 18 years or older; and (4) able to provide written consent. The initial assessment will include: (1) clinical and endoscopic examination of the primary tumor; (2) CT chest, abdomen, and pelvis; and (3) pelvic MRI. All potentially eligible cases will be presented at a multidisciplinary cancer conference to assess for eligibility based on the MRI criteria for "good prognosis" tumor which include: (1) predicted circumferential resection margin (CRM) > 1 mm; (2) definite T2, T2/early T3, or definite T3 tumor with < 5 mm of extramural depth of invasion (EMD); (3) any N0, N1, or N2; and (4) absence of extramural venous invasion (EMVI). All patients fulfilling the MRI criteria for "good prognosis" rectal cancer and the inclusion and exclusion criteria will be invited to participate in the study and proceed to primary surgery. The safety of the MRI criteria will be evaluated by assessing the positive CRM rate and is the primary outcome for the study. RESULTS: We expect to have a minimum of 300 potentially eligible patients, and based on a 30% eligibility rate and 80% participation rate, it is expected that 75 patients will be recruited over the two year study period. A Data Safety Monitoring Committee has been organized, and the study will be stopped if a positive CRM of >10% is reported at any interim assessment, which will occur after every 25 patients accrued in the study. CONCLUSIONS: It is expected that the results of this study will show that use of MRI criteria to identify "good prognosis" rectal cancers eligible for primary surgery will be safe (ie, positive margin less than 10%). Therefore, these results will have significant potential to change the current management of rectal cancer in North America and result in improved quality of life for rectal cancer patients and survivors, while reducing overall health care costs. TRIAL REGISTRATION: ISRCTN05107772; http://www.controlled-trials.com/ISRCTN05107772/ (Archived by WebCite at http://www.webcitation/6WhhUhXkA).