McMaster University

McMaster University

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Health Sciences

Study using PET scans may inform policy for liver cancer surgery

Published: May 14, 2014
Mark Levine
Dr. Mark Levine, professor and chair of Oncology at McMaster University and scientific director of the Escarpment Cancer Research Institute

Imaging tests for some cancer patients may be expensive and unnecessary, according to new research from the Ontario Clinical Oncology Group (OCOG).

Scientists found PET scans, or positron emission tomography, did not significantly change the surgical treatment for patients with colorectal cancer which had already spread to the liver, as shown by computed tomography (CT) scanning.

The results of the study, coordinated by OCOG which is part of the Escarpment Cancer Research Institute at McMaster University and Hamilton Health Sciences is published in the May 14 issue of the Journal of the American Medical Association (JAMA).

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 liver metastases.

Some patients with liver metastases are candidates for surgery to remove the cancer which can increase long term survival rates. However, unidentified metastases outside the liver can render the operation non-curative and thus futile. Therefore, long-term survival following surgical removal of colorectal cancer liver metastases is relatively low.

The usual practice is to perform a CT scan before surgery to determine the extent of the cancer in the liver. Positron emission tomography combined with computed tomography (PET-CT) could help avoid non-curative surgery by identifying patients with hidden metastases.

"There has been a tendency for expensive imaging tests to be adopted in practice without rigorous evaluation," said Dr. Mark Levine, professor and chair of the Department of Oncology at McMaster University and scientific director of the Escarpment Cancer Research Institute.

"Over the last decade OCOG has led a number of clinical trials in Ontario of PET in various cancers to provide the evidence that ultimately helps to inform and change health policy", he said.

Dr. Carol-Anne Moulton and Dr. Steven Gallinger of the University Health Network in Toronto were the principal investigators. Patients with colorectal cancer with surgically-removable metastases based on CT scans were randomized to either PET-CT or no further imaging 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 researchers found no significant difference in survival or disease-free survival between patients in the PET-CT group versus the control group.

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