January 15, 2014
News Review From Harvard Medical School -- Screening May Detect Return of Colon Cancer
Follow-up tests may help show when colon cancer has returned after surgery, a new study finds. The study included 1,200 people who had received colon cancer surgery. They were randomly divided into 4 groups. One group received regular CT scans. Another other group got regular tests for a blood protein, called CEA. At abnormal levels, this protein can be a sign of cancer. A third group got both tests. A fourth group had no special follow-up. Researchers kept track of people for an average of 4.4 years. In that time, 2.3% of those in the group who got no special follow-up had a second surgery because of a return of their colon cancer. Similar surgeries were done in 6.7% of the CEA group and 8% of the CT group. The rate of second surgery was 6.6% in the group that got both tests. About 15.9% of those with minimum follow-up died during the study, compared with 18.2% of all of the CT and CEA groups combined. Those death rates are close enough that the difference could have been caused by chance. The Journal of the American Medical Association published the study January 15. HealthDay News wrote about it.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
After surgery, people diagnosed with colon cancer have a significant risk of developing:
- A return of the same cancer
- A new colon cancer
- Polyps that could later become cancerous
It's best to detect new polyps or a new cancer at the earliest stage. So everyone who has had colon cancer surgery receives regular colonoscopies.
However, cancer experts differ on their strategies to look for a return (recurrence) of the original cancer. Cancer can return just at the site of the surgery (local). But it also can spread to distant places, such as the lymph nodes, liver, lungs or all of these. This is called metastatic cancer.
It seems logical that discovering a recurrence sooner would be better. In fact, people do have longer survival with metastatic cancer if it is discovered before symptoms develop.
But the benefit of finding a recurrence at the original site sooner is not as clear. This study was designed to answer two questions:
- What is the best way to test for a recurrence at the original site that could be cured with repeat surgery?
- Does testing in people without symptoms improve survival compared with close follow-up and no testing?
Two tests are used most often to screen for colon cancer recurrence at the original site:
- CT scans
- A blood test for a tumor protein called CEA (carcinoembryonic antigen)
The new study included 1,202 people who had received surgery that was intended to cure colon cancer. Each person had a colonoscopy after surgery to be sure that no cancer remained.
The patients were randomly assigned to one of four groups:
- No special screening for recurrence
- Regular blood tests for CEA
- Regular CT scans of the lungs, abdomen and pelvis
- Both blood tests and CT scanning
The patients were followed for an average of 4.4 years from the time they enrolled in the study. People assigned to the CEA-only group and those assigned to the CT-scan-only group were more likely to get repeat surgery with intent to cure than people who received no special screening. Interestingly, using both tests did not lead to discovery of an even larger number of recurrences.
This was a very large study. But only a small number of cancers recurred at the original site. This was true even in the group that had no special screening. So the researchers could not make any formal conclusions on survival. But the data suggest that a testing program to find these local recurrences will extend people's lives very little or not at all.
What Changes Can I Make Now?
The treatment of colon cancer has improved dramatically. Survival continues to get better. But it's even more important to help prevent colon cancer. Here's how:
- Get screened with colonoscopy once every 10 years to look for polyps and to have them removed.
- Stay physically active. Dedicate time to exercise each day.
- Don't smoke.
- Use alcohol in small amounts or not at all.
- Maintain a healthy body weight.
Although it's not proven, some other steps may help reduce your colon cancer risk. Here's what else you can do:
- Eat a diet rich in fruits and vegetables.
- Get enough vitamin D through sunlight, diet, pills or all of these.
- Choose whole-grain products that provide more fiber.
Some people have a higher than average risk of colon cancer. They need to get colonoscopies more often than once every 10 years and follow the other prevention advice above. This includes people with:
- A prior diagnosis of colon polyps
- A family history of polyps or colon cancer
- A family history of Lynch syndrome, a genetic condition that leads to higher rates of several types of cancer
- A history of ulcerative colitis or Crohn's disease
What Can I Expect Looking to the Future?
Some patients might opt for fewer CT scans, which expose them to radiation and cost more. They might prefer to get the simpler and less costly CEA blood tests. But the evidence is NOT strong enough to recommend any specific strategy. And it's quite likely this study won't change what most cancer specialists suggest to patients now.