Underutilized test may improve treatment decisions, outcomes in colon cancer
Many patients with colon cancer do not receive a blood test that potentially could alter their treatment decisions and improve survival outcomes, according to study results.
“The decision to give a patient chemotherapy after surgery is not a light one, and physicians must weigh the risks and benefits,” Kellie L. Mathis, MD, colon and rectal surgeon at Mayo Clinic in Rochester, Minnesota, said in a press release. “We are currently using the blood test to help make these difficult decisions, and we suggest other physicians do the same.”
The carcinoembryonic antigen test measures the level of carcinoembryonic antigen (CEA) in the blood. Higher levels of CEA are found with certain cancer types, particularly colon and rectal cancers.
Mathis and colleagues hypothesized that known levels of CEA could improve preoperative risk stratification for patients with colon cancer.
Researchers used the National Cancer Data Base to gather data on 74,945 patients with stage II colon cancer. Investigators used a novel risk stratification to assess certain factors, including T4 lesion, poor differentiation and elevated CEA levels.
Only 54.5% of all patients had CEA levels reported. However, researchers reported a significantly higher rate of 5-year OS among patients with normal CEA levels than those with elevated CEA levels (74.5% vs. 63.4%; P<.001).
“Knowing these blood test results before treatment could have changed the classification from average risk to high risk in 17% of patients, ... [and] treatment options could have been altered appropriately,” Mathis and colleagues wrote.
HemOnc Today spoke with Mathis about the CEA test, the type of information it provides, how the results can be used to inform treatment decisions, and potential explanations for why the test is not administered to all patients who can derive benefit.
Question: How does the test work?
Answer: It is simply a blood test that measures the amount of CEA, a protein present in everyone’s blood. The protein is present in higher levels in the bloodstream of patients with certain cancers, particularly colon and rectal cancers. It should be used at the time of any new diagnosis of colon or rectal cancer. A high level of CEA for these individuals often will indicate they have widely metastatic disease. However, there are patients who will have high levels without metastatic disease, and those are the patients we were interested in for this study. The presence of high CEA levels at the beginning is concerning for high risk for recurrence later in life. The test gives us information about the patient’s prognosis and their recurrence risk.
Q: How can the test be used to inform treatment decisions?
A: For patients with stage II colon cancer, when CEA is elevated before they start treatment, we believe that — based upon the results of this study — they are at higher risk for recurrence. In addition to standard surgery, we recommend patients with stage II colon cancer and a high CEA after surgery see a medical oncologist to consider chemotherapy.
Q : How frequently is the test administered?
A: It should be administered at baseline, after completion of any treatments, and then every 3 to 6 months for the next 5 years. If the CEA levels remain normal throughout this 5-year timeframe, then we assume the patient is cancer free and we stop checking CEA levels.
Q: Why is the test not administered to all patients who can benefit?
A: We were surprised to find only 54% of patients had a CEA level reported. We do not know if some of the unreported patients did have their levels checked, but it just was not placed into the database. The national guidelines are clear: Every patient with a new diagnosis of colon or colorectal cancer should have a blood test at the time of diagnosis. This is our practice at Mayo Clinic. It is possible a provider feels that — because it is a lower-stage tumor that was caught early — maybe a test would not have a lot of benefit for the patient. This often is why the test may be overlooked or omitted. But I think this study furthers the data to say we do need to know the CEA level because it may affect a change in treatment decisions, even for early-stage tumors.
Q: What needs to happen to increase the rate at which the test is administered?
A: The national guidelines are clear and providers should know they should be checking CEA levels for every patient with a new diagnosis of colon cancer. Spreading this information to patients, so everyone knows what a CEA test is, increases the chance that a patient will ask their physician or surgeon what their CEA level is. That may prompt initiation of the test.
Q: Is there anything else that you would like to mention?
A: There will be patients with early-stage disease who fare poorly, despite good surgery. We want to find those patients ahead of time and determine if there are other things we can do to improve their prognosis and their chance for long-term survival. We believe the CEA test will be one piece of this puzzle that will help us make the right decisions for patients. – by Jennifer Southall
For more information:
Kellie L. Mathis, MD, can be reached at Mayo Clinic, 200 First St. SW, Rochester, MN 55905.
Disclosure: Mathis reports no relevant financial disclosures.