FDG-PET test may not aid in deciding on surgery for colorectal cancer that has spread to the liver

Deciding which patients with liver metastases from colon or rectal cancer will benefit from surgery to remove them can be difficult.  Surgery is usually not helpful if cancer has also spread outside the liver or if liver tumors are extensive.

Traditionally CT scans have helped surgeons and patients make decisions about appropriate surgery.  PET scanning with fluorodeoxyglucose (FDG) uses a different technique to identify cancer both in and outside the liver.  Adding a radioactive tracer to glucose lights up areas in the body where cancer absorbs more of the glucose.

But does adding FDG-PET scanning provide better information to decide on surgery?

Surgeons in the Netherlands compared two groups of patients who had surgery to remove colorectal liver metastases.  The first group (A) was chosen on the basis of traditional CT-scanning.  The second group (B) had FDG-PET scans added to the decision-making process.

During surgery, doctors found that liver resection was not possible in about 30% of the Group A patients and 20% of group B.  It was more common to find that cancer had spread outside the liver in the CT-only group A.  Ten percent of those surgeries were not completed because of extra-hepatic mets compared to only 2% of those who had the additional PET study before surgery.  In the rest of the unresectable cases, the liver spread itself was too widespread to remove.

Despite being able to find extra-hepatic cancer spread, using FDG-PET scanning added little to either survival or disease-free survival.   Three years after surgery 57 percent of Group A survived and 60 percent of Group B, with PET scanning, were also alive.  Cancer-free survival for group A was 23 percent compared to 30 percent in Group B, which was not significant.

B. Wiering and colleagues concluded:

In patients with colorectal liver metastases, FDG-PET may reduce the number of negative laparotomies. However, the effect size on the selection of these patients seems not sufficient enough to affect the overall and disease-free survival after treatment.

SOURCE:  Wiering et. al., Annals of Surgical Oncology, Volume 14, Number 2, pages 771-779, February 2007.

WHAT THIS MEANS FOR PATIENTS

Surgery to remove liver mets can lead to cures for advanced colorectal cancer in carefully selected patients.  Choosing which patients are likely to benefit depends on imaging before surgery.  If tumors in the liver are too extensive to permit the liver to function after surgery, an operation may have to be abandoned once begun.

In addition, cancer that has spread outside the liver and cannot be removed may make liver surgery futile.

Surgery has risks, including pain and complications.  Recovery reduces the possibility of chemotherapy that may increase survival time.  So selecting who can benefit and who will not is very important.

In this study, researchers found that FDG-PET did identify more cancer outside the liver, but knowing this information didn’t seem to change either survival at three years or cancer-free survival.

CT-scanning alone may be sufficient in making a decision about having liver resection surgery.