FDG-PET/CT has a "significant role" in characterizing suspected colorectal cancer recurrence at an early stage, according to a study presented by U.K. researchers at the American Roentgen Ray Society (ARRS) meeting this week in San Diego.
The researchers from Christie NHS Foundation Trust in Manchester, U.K., also found that FDG-PET/CT can detect recurrent disease in patients with elevated levels of carcinoembryonic antigen, which is associated with tumors. The results were detailed by lead study author Dr. Rohit Kochhar.
Kochhar and colleagues retrospectively reviewed clinical histories of all colorectal cancer patients who received FDG-PET/CT scans for suspected recurrent disease at their facility between April 2007 and August 2008.
Patients then were separated into one group with suspected local recurrence detected on conventional CT or MRI scans, and a second group in which recurrence was indicated by a carcinoembryonic antigen level greater than 5 ng/mL with equivocal or negative conventional imaging. There were 51 subjects in the first group and 20 patients in the second group.
When FDG-PET/CT did not show evidence of cancer or findings were equivocal, FDG-PET/CT results were validated by follow-up pathological or imaging findings.
In the first group, FDG-PET/CT confirmed local recurrence of colorectal cancer in 27 (52%) of 51 patients. In 12 (23%) of those 51 patients, clinicians also found evidence of cancer elsewhere. FDG-PET/CT also characterized suspected local recurrence as nonmalignant in 16 (31%) of 51 patients. Six patients received no follow-up based on the FDG-PET/CT results.
Follow-up imaging confirmed benign local lesions in nine patients but showed local recurrence in one patient (false-negative FDG-PET/CT). FDG-PET/CT was indeterminate in eight (15%) of 51 cases. One patient underwent surgery to remove a local lesion, five lesions were characterized as nonmalignant, and two lesions remained indeterminate based on follow-up imaging.
In the second group, FDG-PET/CT detected recurrent disease in 13 (65%) of the 20 patients. The findings included isolated local cancer in three cases, lung cancer in one patient, liver cancer in two patients, a nodal cancer in one patient, and bone lesions in one patient. In five cases, there was more than one site of cancer recurrence.
FDG-PET/CT was equivocal in three patients and showed no sign of disease in four patients. Of those seven patients, one had a hepatectomy for an equivocal hepatic lesion.
The remaining patients received imaging follow-up, ranging from 267 to 661 days. Follow-up imaging was normal in three patients and showed recurrent disease in the other three patients in the peritoneal, omental, and pelvic side wall, respectively.
With FDG-PET/CT accurately confirming recurrence of colorectal cancer in 40 (56%) of 71 patients, the results show that the hybrid modality has a definite role in managing patients with recurrent colorectal cancer in addition to conventional imaging and the carcinoembryonic antigen test, noted Kochhar.
FDG-PET/CT has a "significant role in characterizing suspected local disease and in detecting recurrent disease in patients with elevated carcinoembryonic antigen," the researchers wrote. "However, in patients with negative or indeterminate PET/CT, clinical correlation and histological or imaging follow-up is recommended."
The early detection and confirmation of colorectal cancer also can help in treatment planning and targeted patient care, according to the group.
By Wayne Forrest
AuntMinnie.com staff writer
May 5, 2010
Related Reading
Providers don't adequately discuss colon cancer screening, April 13, 2010
FDG-PET/CT outdoes MDCT in certain colorectal cancer patients, February 22, 2010
NIH urges new efforts to increase colorectal cancer screening, February 4, 2010
Medicare coverage spurs 41% growth in colorectal cancer PET use, January 26, 2010
PET testing reduces futile resections for colorectal liver metastases, August 17, 2009
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