According to a new study published in JAMA Oncology, in patients with colon cancer, postoperative – but not preoperative – serum carcinoembryonic antigen (CEA) levels may predict recurrence risk.

At Memorial Sloan Kettering Cancer Center in New York City, Dr. Martin Weiser and colleagues reviewed data on 1,027 colon cancer patients (median age, 64; 50% men) who had undergone curative resection from 2007 through 2014. For the study, the patients were grouped by time-specific CEA levels: normal preoperative; elevated preoperative but normal postoperative; and elevated preoperative and postoperative.

Postoperative CEA was defined as the last CEA value within 12 weeks after surgery, before starting adjuvant chemotherapy. The three-year rate of recurrence-free survival (RFS) for patients with normal preoperative CEA (89.7%) was significantly higher than for the two combined groups with elevated preoperative CEA (82.3%) but similar to that of patients with normal postoperative CEA (87.9%).

RFS at three years was significantly lower for patients with elevated postoperative CEA than for the combined cohorts with normal postoperative CEA (74.5% vs. 89.4%). The hazard of recurrence with elevated postoperative CEA peaked earlier than for the other cohorts, and multivariate analyses confirmed that elevated postoperative CEA (hazard ratio, 2.0), but not normal postoperative CEA, was independently associated with shorter RFS.

The researchers suggested that routine measurement of postoperative, rather than preoperative, CEA is warranted and that postoperative CEA, rather than preoperative CEA, should be utilized for risk assessment. Interestingly, patients with high postoperative CEA also experienced earlier recurrence than patients who had a normal baseline or postoperative CEA level.

Therefore, postoperative CEA is more informative than preoperative CEA, and elevated postoperative CEA can be utilized to risk-stratify surveillance regimens. Dr. Neal Meropol of Flatiron Health in New York City, coauthor of an accompanying editorial, said the study challenges key assumptions that are currently held by oncologists who take care of patients with colon cancer.

It is commonly believed that CEA should be measured in blood before surgery for colon cancer, as this helps predict who is most likely to relapse. Also, there is a common myth that checking the CEA blood test in follow-up may only be useful in detecting cancer recurrence if it was high before the operation.

The findings revealed that the CEA level is often high at the time of recurrence, although it was normal before the original tumor was removed. Thus, CEA testing should be done regularly over time after surgery, regardless of whether (high levels) were present at the time of original diagnosis.