Underused Blood Test Could Improve Treatment for Large Swath of Patients With Colon Cancer

Key Points

  • Knowing CEA test results prior to treatment could have changed the classification for 17% of stage II colon cancer patients from average risk to high-risk.
  • The blood test has been around for decades, but is not broadly used across the country. It was recorded in 54% of cases meeting other relevant criteria for the study.
  • For stage II patients who had surgery but not chemotherapy, the 5-year survival rate was 66% for those with elevated protein levels and 76% for those without elevated levels. For patients with elevated protein levels, those who had chemotherapy and surgery fared better than those who only had surgery.

A simple blood test could improve treatment for more than one in six patients with stage II colon cancer, suggests new research from the Mayo Clinic. Researchers also discovered that many patients who could benefit from the test likely aren’t receiving it. These findings were published by Spindler et al in the Journal of Gastrointestinal Surgery.

Using data from the National Cancer Database for 40,844 patients, physicians and scientists teamed up to look at benefits of a blood test that measures the protein called carcinoembryonic antigen (CEA) in stage II colon cancer. CEA can be found in higher levels in people with certain cancers, especially colon cancer.

Study Findings

The researchers found that knowing these blood test results prior to treatment could have changed the classification for 17% of stage II colon cancer patients from average risk to high-risk. That change could have altered treatment options, including whether to use chemotherapy.

“The decision to give a patient chemotherapy after surgery is not a light one, and physicians must weigh the risks and benefits,” said senior author Kellie Mathis, MD, a colon and rectal surgeon at the Mayo Clinic. “We are currently using the blood test to help make these difficult decisions, and we suggest other physicians do the same.”

The blood test has been around for decades, but is not broadly used across the country. It was recorded in 54% of cases meeting other relevant criteria for the study. While in some cases the test may not have been entered in the database, many other patients may not be getting it.

“There is no good reason for a physician to omit this blood test, and more work needs to be done to ensure that all patients receive it,” Dr. Mathis said.

The authors pointed out that when the blood test is in fact given, it is often conducted after surgery to monitor the cancer’s development. Greater and earlier consideration of protein level may be warranted, the researchers explained.

Generally, in stage II colon cancer, the disease hasn’t spread to nearby lymph nodes or distant organs, but has grown into or through the wall of the colon. Some stage II patients fare worse than some stage III patients, who usually benefit most from chemotherapy. But the research team believes this blood test can help determine which stage II patients are at a higher risk and therefore could benefit from therapy.

The researchers also discovered that, for stage II patients who had surgery but not chemotherapy, the 5-year survival rate was 66% for those with elevated protein levels and 76% for those without elevated levels. For patients with elevated protein levels, those who had chemotherapy and surgery fared better than those who only had surgery.

“If a patient with a new diagnosis of stage II colon cancer has an elevated carcinoembryonic antigen level, physicians should consider chemotherapy in addition to surgery,” concluded Dr. Mathis.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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