Newswise — Hamilton, ON (May 14, 2014) - 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.


“There has been a tendency for expensive imaging tests to be adopted in practice without rigorous evaluation. OCOG has played an important role in conducting clinical trials to provide the evidence that ultimately helps to inform and change health policy.” ~ Dr. Mark Levine, Co-Director, OCOG, is Professor and Chair Department of Oncology, and holds the Buffett Taylor Chair Breast Cancer Research, McMaster University. He is Scientific Director of the Escarpment Cancer Research Institute.

“To our knowledge, our study is the largest, based on high-quality imaging and reading of scans, to understand the role of PET-CT in selecting the best colorectal cancer candidates whose cancer has spread to the liver for surgery. We did not anticipate that PET-CT would have such a small impact on hepatic surgery in our patients.” ~ Dr. Steven Gallinger, Co-Principal Investigator of the clinical trial, Head, Hepatobiliary/Pancreatic Surgical Oncology Program, University Health Network and Mount Sinai Hospital, and Professor of Surgery, University of Toronto. “The decision to adopt a new medical practice or additional test should be informed by rigorous evidence on its effectiveness, benefits, along with any possible harmful effects. In a health care environment where patients want and need to have the best information to make informed decisions, research on the effectiveness of a specific treatment or test will become increasingly important to help patients and their physicians understand all the facts.” ~ Dr. Carol-Anne Moulton, Co-Principal Investigator of the clinical trial, surgeon in the Hepatobiliary/Pancreatic Surgical Oncology Program, University Health Network, and Associate Professor of Surgery, University of Toronto.

Note to Editors: Dr. Mark Levine, Scientific Director of the Escarpment Cancer Research Institute at McMaster University is available for comment.

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Journal of the American Medical Association