Study: PET Superior to CT Scan for Detecting Colon Cancer Spread

Whole body positron emission tomography (PET) scans are significantly more accurate than CT scans in detecting the spread of colon cancer, according to researchers at Drexel University College of Medicine in Philadelphia.

Dr. Simin Dadparvar reported at the annual meeting of the American Roentgen Ray Society on a study of 35 patients between the ages of 40 and 83 with various stages of colon cancer who underwent both PET and CT scans.

CT imaging has been used for many years to detect cancer spread in soft tissues.

But Dadparvar reported that the PET scans were more than twice as sensitive at CT scans in detecting the spread of colon cancer, and had an accuracy rate of 93 percent compared to 56 percent for CT imaging.

In addition to the high level of accuracy, the PET scan also means less radiation exposure for the patient. The radioisotope, 18 Fluorodeoxyglucose, is injected into the vein one hour before the whole body PET examination. The majority of the radioactive material is excreted by the kidneys about eight hours after the examination.

A CT examination requires multiple scans of different parts of the body, providing more exposure to radiation. Since the PET scan can detect cancer spread to both soft tissue and bone, the patient needs only the one test instead of both a CT examination and a bone scan.

Although PET scans still tend to only be available in major cities, Dadparvar recommended using PET over CT for staging of patients with suspected cancer spread, restaging of patients who have already been treated for cancer, and evaluation of patients with “rising CEA as a tumor marker” for recurrent colon cancer.

Other Sources: American Roentgen Ray Society Annual Meeting