Among patients with colorectal cancer which has spread to the liver as determined by computed tomography (CT) scanning, further imaging using positron emission tomography (PET) scans before surgery did not significantly change the surgical treatment of the cancer compared with no further imaging, according to an Ontario Clinical Oncology Group (OCOG) study led by University Health Network researchers.
In Canada, cancer of the colon or rectum (colorectal) is a leading cause of cancer death. Patients with colorectal cancer undergo surgery to remove the cancer, but approximately 50 percent of patients develop spread of the cancer to the liver (liver metastases). Some patients with liver metastases are candidates for liver surgery in order to remove the cancer which can lead to long term survival. However, unidentified metastases outside the liver at the time of surgery can render the operation non-curative and thus futile. Therefore, long-term survival following surgical removal of colorectal cancer liver metastases is relatively low, about 50 percent. The usual practice is to perform a CT scan before surgery to determine the extent of the cancer. Positron emission tomography combined with computed tomography (PET-CT) could help avoid non-curative surgery by identifying patients with hidden metastases.
The findings are published in the May 14 issue of the Journal of the American Medical Association (JAMA).
Principal Investigators, Dr. Carol-Anne Moulton and Dr. Steven Gallinger, and their Ontario colleagues, randomly assigned patients with colorectal cancer with surgically-removable metastases based on CT scans to either PET-CT or no further imaging (control) to determine the effect on the surgical management of these patients.
The study, conducted between 2005 and 2013, enrolled 404 patients and involved 21 surgeons at nine hospitals in Ontario.
Of the 263 patients who received PET-CT scans, 159 had no new information on PET-CT; 49 had new abnormal or suspicious lesions on PET-CT and in 62 the PET-CT did not identify the lesion in the liver identified on the baseline CT. Change in management (canceled, more extensive liver surgery, or surgery performed on additional organs) as a result of the PET-CT findings occurred in 8.7 percent of cases; only 2.7 percent avoided non-curative liver surgery. Overall, liver resection was performed on 91 percent of patients in the PET-CT group and on 92 percent of the control group.
The median follow-up was three years. The researchers found no significant difference in survival or disease-free survival between patients in the PET-CT group versus the control group.
The PET-CAM trial is one of 7 trials that OCOG has performed in recent years as part of the Provincial PET in Oncology Program. The results of these studies have informed policy for the Ontario Ministry of Health & Long Term Care on whether to fund PET for a specific indication. OCOG is the world leader in conducting trials to evaluate the utility of PET in oncology.
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