PET-CT Does Not Avoid Surgery in Colorectal Cancer Patients

Use of PET-CT before surgery among patients with potentially resectable hepatic metastases from colorectal cancer does not significantly change the surgical treatment, according to a study published in JAMA.

Researchers from Canada sought to determine if there was value in imaging prior to surgery for colorectal cancer, and if the use of imaging would result in avoidance of noncurative surgery. According to the study, approximately 50 percent of patients have cancer spread to the liver. Some patients with liver metastases are candidates for surgery to have the cancer removed; however, previously unidentified occult metastases discovered during the time of surgery can render the operation noncurative. The study determined whether PET-CT imaging could identify patients with occult metastases prior to surgery, and therefore avoid noncurative surgery in these patients.

The multi-center randomized trial included adult patients with colorectal cancer who:

• Were treated with surgery

• Had resectable metastases based on CT scans of the chest, abdomen, and pelvis within the previous 30 days

• Had a clear colonoscopy within the previous 18 months

A total of 263 patients underwent PET-CT scans, 134 controls underwent CT only. While there was new information for 111 of the PET-CT patients (62 were classified as negative and 49 had abnormal or suspicious lesions), there was a change in surgical management for only 21:

• Seven (2.7 percent) did not undergo laparotomy

• Four (1.5 percent) underwent more extensive hepatic surgery

• Nine (3.4 percent) underwent additional organ surgery

• One patient underwent surgery to open the abdominal cavity, but hepatic surgery was not performed and the cavity was closed

Liver resection rates were similar for both groups: 91 percent of patients in the PET-CT group and 92 percent of the control group. Follow-up of 36 months showed an estimated mortality rate of 11.13 events/1,000 person-months for the PET-CT group and 12.71 events/1,00 person-months for the control group.

The researchers concluded that use of PET-CT in this patient group did not frequently change surgical management so the value for the examinations is questionable.