The Role of High Frequency Dynamic Threshold (HiDT) Serum Carcinoembryonic Antigen (CEA) Measurements in Colorectal Cancer Surveillance: A (Revisited) Hypothesis Paper

Serum carcinoembryonic antigen trends for diagnosing colorectal cancer recurrence in the FACS randomized clinical trial

BACKGROUND

Most guidelines recommend that patients who have undergone curative resection for primary colorectal cancer are followed up for 5 years with regular blood carcinoembryonic antigen (CEA) tests to trigger further investigation for recurrence. However, CEA may miss recurrences, or patients may have false alarms and undergo unnecessary investigation.

METHODS

The diagnostic accuracy of trends in CEA measurements for recurrent colorectal cancer, taken as part of the FACS (Follow-up After Colorectal Surgery) trial (2003-2014), were analysed. Investigation to detect recurrence was triggered by clinical symptoms, scheduled CT or colonoscopy, or a CEA level of at least 7 μg/l above baseline. Time-dependent receiver operating characteristic (ROC) curve analysis was used to compare the diagnostic accuracy of CEA trends with single measurements. CEA trends were estimated using linear regression.

RESULTS

The area under the ROC curve (AUC) for CEA trend was at least 0·820 across all 5 years of follow-up. In comparison, the AUCs for single measurements ranged from 0·623 to 0·749. Improvement was most marked at the end of the first year of follow-up, with the AUC increasing from 0·623 (95 per cent c.i. 0·509 to 0·736) to 0·880 (0·814 to 0·947). However, no individual trend threshold achieved a sensitivity above 70 per cent (30 per cent missed recurrences).

CONCLUSION

Interpreting trends in CEA measurements instead of single CEA test results improves diagnostic accuracy for recurrence, but not sufficiently to warrant it being used as a single surveillance strategy to trigger further investigation. In the absence of a more accurate biomarker, monitoring trends in CEA should be combined with clinical, endoscopic and imaging surveillance for improved accuracy.

What carcinoembryonic antigen level should trigger further investigation during colorectal cancer follow-up? A systematic review and secondary analysis of a randomised controlled trial

BACKGROUND

Following primary surgical and adjuvant treatment for colorectal cancer, many patients are routinely followed up with blood carcinoembryonic antigen (CEA) testing.

OBJECTIVE

To determine how the CEA test result should be interpreted to inform the decision to undertake further investigation to detect treatable recurrences.

DESIGN

Two studies were conducted: (1) a Cochrane review of existing studies describing the diagnostic accuracy of blood CEA testing for detecting colorectal recurrence; and (2) a secondary analysis of data from the two arms of the FACS (Follow-up After Colorectal Surgery) trial in which CEA testing was carried out.

SETTING AND PARTICIPANTS

The secondary analysis was based on data from 582 patients recruited into the FACS trial between 2003 and 2009 from 39 NHS hospitals in England with access to high-volume services offering surgical treatment of metastatic recurrence and followed up for 5 years. CEA testing was undertaken in general practice.

RESULTS

In the systematic review we identified 52 studies for meta-analysis, including in aggregate 9717 participants (median study sample size 139, interquartile range 72-247). Pooled sensitivity at the most commonly recommended threshold in national guidelines of 5 µg/l was 71% [95% confidence interval (CI) 64% to 76%] and specificity was 88% (95% CI 84% to 92%). In the secondary analysis of FACS data, the diagnostic accuracy of a single CEA test was less than was suggested by the review [area under the receiver operating characteristic curve (AUC) 0.74, 95% CI 0.68 to 0.80]. At the commonly recommended threshold of 5 µg/l, sensitivity was estimated as 50.0% (95% CI 40.1% to 59.9%) and lead time as about 3 months. About four in 10 patients without a recurrence will have at least one false alarm and six out of 10 tests will be false alarms (some patients will have multiple false alarms, particularly smokers). Making decisions to further investigate based on the trend in serial CEA measurements is better (AUC for positive trend 0.85, 95% CI 0.78 to 0.91), but to maintain approximately 70% sensitivity with 90% specificity it is necessary to increase the frequency of testing in year 1 and to apply a reducing threshold for investigation as measurements accrue.

LIMITATIONS

The reference standards were imperfect and the main analysis was subject to work-up bias and had limited statistical precision and no external validation.

CONCLUSIONS

The results suggest that (1) CEA testing should not be used alone as a triage test; (2) in year 1, testing frequency should be increased (to monthly for 3 months and then every 2 months); (3) the threshold for investigating a single test result should be raised to 10 µg/l; (4) after the second CEA test, decisions to investigate further should be made on the basis of the trend in CEA levels; (5) the optimal threshold for investigating the CEA trend falls over time; and (6) continuing smokers should not be monitored with CEA testing. Further research is needed to explore the operational feasibility of monitoring the trend in CEA levels and to externally validate the proposed thresholds for further investigation.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015019327 and Current Controlled Trials ISRCTN93652154.

FUNDING

The main FACS trial and this substudy were funded by the National Institute for Health Research Health Technology Assessment programme.

Application and Indication of Carcinoembryonic Antigen Triggered 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scanning in the Detection of Relapse of Colorectal Cancer Patients After Curative Therapy

OBJECTIVE

This study aimed to explore the characteristics of patients with colorectal cancer (CRC) following curative therapy that may benefit from fluorine-18-2-uoro-2-deoxy-D-glucose positron emission tomography/computed tomography (F-FDG PET/CT) scanning, evaluate the application of carcinoembryonic antigen (CEA)-triggered F-FDG PET/CT scanning, and provide referential indicators.

METHODS

This retrospective study included 56 CRC patients who received a PET/CT scan as a primary examination because of rising CEA levels after curative therapy and who had not received any other radiological examinations previously.

RESULTS

The rate of recurrence or metastasis was 75.0% by PET/CT scan but was 69.6% with follow-up treatment. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 94.9%, 70.6%, 87.5%, 88.1%, and 85.7%, respectively. TNM (tumor, node, metastasis) stage, body mass index, and CEA level were significant prognostic factors.

CONCLUSIONS

Positron emission tomography/CT can be selectively applied as a primary examination in CRC patients with asymptomatic elevation of CEA. High CEA levels, increased body mass index, and advanced TNM staging are risk factors for relapse.

Survival analysis of the CEAwatch multicentre clustered randomized trial

BACKGROUND

The CEAwatch randomized trial showed that follow-up with intensive carcinoembryonic antigen (CEA) monitoring (CEAwatch protocol) was better than care as usual (CAU) for early postoperative detection of colorectal cancer recurrence. The aim of this study was to calculate overall survival (OS) and disease-specific survival (DSS).

METHODS

For all patients with recurrence, OS and DSS were compared between patients detected by the CEAwatch protocol versus CAU, and by the method of detection of recurrence, using Cox regression models.

RESULTS

Some 238 patients with recurrence were analysed (7·5 per cent); a total of 108 recurrences were detected by CEA blood test, 64 (55·2 per cent) within the CEAwatch protocol and 44 (41·9 per cent) in the CAU group (P = 0·007). Only 16 recurrences (13·8 per cent) were detected by patient self-report in the CEAwatch group, compared with 33 (31·4 per cent) in the CAU group. There was no significant improvement in either OS or DSS with the CEAwatch protocol compared with CAU: hazard ratio 0·73 (95 per cent 0·46 to 1·17) and 0·78 (0·48 to 1·28) respectively. There were no differences in survival when recurrence was detected by CT versus CEA measurement, but both of these methods yielded better survival outcomes than detection by patient self-report.

CONCLUSION

There was no direct survival benefit in favour of the intensive programme, but the CEAwatch protocol led to a higher proportion of recurrences being detected by CEA-based blood test and reduced the number detected by patient self-report. This is important because detection of recurrence by blood test was associated with significantly better survival than patient self-report, indirectly supporting use of the CEAwatch protocol.

Cost-effectiveness of a carcinoembryonic antigen (CEA) based follow-up programme for colorectal cancer (the CEA Watch trial)

AIM

The study CEA Watch (Netherlands Trial Register 2182) has shown that an intensified follow-up schedule with more frequent carcinoembryonic antigen (CEA) measurements but fewer outpatient visits detects more curable recurrences compared with the usual follow-up protocol in colorectal cancer (CRC) patients. The aim of the study was to compare the cost and cost-effectiveness between various follow-up programmes.

METHOD

In total, 3223 patients with stage I-III CRC were followed between October 2010 and October 2012. Direct medical costs were calculated per patient adding the costs for all visits, CEA measurements and imaging. Productivity losses and travel expenses were calculated using answers from questionnaires. The cost-effectiveness displayed the additional costs per additional patient with recurrent disease and used an incremental cost-effectiveness ratio (ICER) to compare them.

RESULTS

The mean yearly cost per patient was €548 in the intensified protocol and €497 in the control protocol. The ICER was €94 (95% CI €76-€157) per cent; to detect one additional patient with a recurrence in the intervention protocol compared with the control protocol would require an additional €9400. For curable recurrences, the ICER was €607 (95% CI €5695-€5728). Annual patient-reported costs were €509 per year in the intervention protocol and €488 in the control protocol.

CONCLUSION

The current study demonstrates that the direct medical and patient-reported cost of a newly introduced, safe and effective way of CRC follow-up was comparable to that of standard care. The ICER per curable recurrence was considered acceptably low.

Strengths and weaknesses of a stepped wedge cluster randomized design: its application in a colorectal cancer follow-up study

OBJECTIVES

To determine the advantages and disadvantages of a stepped wedge design for a specific clinical application.

STUDY DESIGN AND SETTING

The clinical application was a pragmatic cluster randomized surgical trial intending to find an increased percentage of curable recurrences in patients in follow-up after colorectal cancer. Advantages and disadvantages of the stepped wedge design were evaluated, and for this application, new advantages and disadvantages were presented.

RESULTS

A main advantage of the stepped wedge design was that the intervention rolls out to all participants, motivating patients and doctors, and a large number of patients who were included in this study. The stepped wedge design increased the complexity of the data analysis, and there were concerns regarding the informed consent procedure. The repeated measurements may bring burden to patients in terms of quality of life, satisfaction, and costs.

CONCLUSION

The stepped wedge design is a strong alternative for pragmatic cluster randomized trials. The known advantages hold, whereas most of the disadvantages were not applicable to this application. The main advantage was that we were able to include a large number of patients. Main disadvantages were that the informed consent procedure can be problematic and that the analysis of the data can be complex.

Changing patterns of recurrent disease in colorectal cancer

BACKGROUND

Due to changes in staging, (neo)-adjuvant treatment and surgical techniques for colorectal cancer (CRC), it is expected that the recurrence pattern will change as well. This study aims to report the current incidence of, and time to recurrent disease (RD), further the localization(s) and the eligibility for successive curative treatment.

METHODS

A consecutive cohort of CRC patients, whom were routinely staged with CT and underwent curative treatment according to the national guidelines, was analyzed (n = 526).

RESULTS

After a mean and median FU of 39 months, 20% of all patients and 16% of all AJCC stage 0-III patients had developed RD. The annual incidences were the highest in the first two years but tend to retain in the succeeding years for stage 0-III patients. The majority of RD was confined to one organ (58%) and 28% of these patients were again treated with curative intent.

CONCLUSIONS

In follow-up nowadays, less recurrences are found than reported in historical studies but these can more often be treated with curative intent. A main cause for the decreased incidence of RD, next to improvements in treatment, is probably stage shift elicited by pre-operative staging. The outcomes support continuation of follow-up in colorectal cancer.