Evaluation of Serum Carcinoembryonic Antigen Monitoring in the follow-up of Colorectal Cancer Patients with Metastatic Lymph Nodes and a Normal Preoperative Serum Level

Negative CEA values in Metastatic Colorectal Carcinoma and the Likelihood of Complete Chemotherapy Response

Introduction

Experimental results reported in the literature have suggested that CEA might inhibit host defense mechanisms and that immunotolerance to CEA could play an important role in the development of metastases in colorectal carcinoma. It might therefore be assumed that negative CEA values during metastatic disease represent a favorable prognostic factor. Surprisingly, there are very few data available about negative CEA. The aim of this study was to determine the significance of negative initial CEA values in patients with metastatic colorectal carcinoma.

Patients and Methods

Initial CEA values were determined in 114 patients with metastatic colorectal carcinoma. The patients were divided into three groups according to these values: I (n=22) <5 ng/mL; II (n=33) 5-100 ng/mL; III (n=59) >100 ng/mL.

Results

Seven/114 complete responses (CR), 22/114 partial responses (PR), 45/114 instances of stable disease (SD) and 38/114 of progressive disease (PD) were registered, while two patients were not evaluable. There were six long-lasting CRs (median 24 months, range 10–37 months) in the CEA-negative patient subset, while in the CEA-positive subset there was only one CR, in a patient with an initial CEA level of 18 ng/mL. The mean initial CEA values in the different response categories were: CR: 4.0 ng/mL; PR: 436 ng/mL; SD: 1442 ng/mL; PD: 6071 ng/mL. The likelihood of response, in particular CR, was highly dependent upon CEA levels (Fisher's exact test, 0.00001). The median survival decreased significantly with increased values of CEA (p=0.006).

Conclusion

Negative CEA in metastatic disease was the main characteristic of the patient subset capable of attaining CR. When relapsing, all patients but one became CEA positive.

The diagnostic accuracy of carcinoembryonic antigen to detect colorectal cancer recurrence - A systematic review

INTRODUCTION

Carcinoembryonic Antigen (CEA) has been used as a tumor marker in the follow-up of colorectal cancer for more than 40 years. Controversy exists regarding its diagnostic applicability due to a relatively low sensitivity and a questionable effect on mortality. The aim of this review was to assess the diagnostic accuracy of CEA in detecting recurrence after intended curative surgery for primary colorectal cancer.

METHODS

Systematic literature searches were performed in PubMed, EMBASE and Cochrane databases, and articles were chosen based on predefined inclusion criteria. Reference lists from included articles were manually searched for additional publications of relevance.

RESULTS

Forty-two original studies with generally representative populations and long follow-up were included. Data were reported on outcomes from 9,834 CEA tests during follow-up. Reporting on the reference standards used was not optimal. Sensitivity of CEA ranged from 17.4 % to 100 %, specificity ranged from 66.1 % to 98.4 %, positive predictive value ranged from 45.8 % to 95.2% and negative predictive value ranged from 74.5 % to 100 %.

CONCLUSION

Results point toward a sensitivity of CEA ranging between 50 % and 80 %, and a specificity and negative predictive value above 80 %. Results on positive predictive value showed low reliability. Overall, CEA did not effectively detect treatable recurrences at an early stage, and a clinically relevant effect on patient mortality remains to be proven.

Blood CEA levels for detecting recurrent colorectal cancer

BACKGROUND

Testing for carcino-embryonic antigen (CEA) in the blood is a recommended part of follow-up to detect recurrence of colorectal cancer following primary curative treatment. There is substantial clinical variation in the cut-off level applied to trigger further investigation.

OBJECTIVES

To determine the diagnostic performance of different blood CEA levels in identifying people with colorectal cancer recurrence in order to inform clinical practice.

SEARCH METHODS

We conducted all searches to January 29 2014. We applied no language limits to the searches, and translated non-English manuscripts. We searched for relevant reviews in the MEDLINE, EMBASE, MEDION and DARE databases. We searched for primary studies (including conference abstracts) in the Cochrane Central Register of Controlled Trials (CENTRAL), in MEDLINE, EMBASE, and the Science Citation Index & Conference Proceedings Citation Index - Science. We identified ongoing studies by searching WHO ICTRP and the ASCO meeting library.

SELECTION CRITERIA

We included cross-sectional diagnostic test accuracy studies, cohort studies, and randomised controlled trials (RCTs) of post-resection colorectal cancer follow-up that compared CEA to a reference standard. We included studies only if we could extract 2 x 2 accuracy data. We excluded case-control studies, as the ratio of cases to controls is determined by the study design, making the data unsuitable for assessing test accuracy.

DATA COLLECTION AND ANALYSIS

Two review authors (BDN, IP) assessed the quality of all articles independently, discussing any disagreements. Where we could not reach consensus, a third author (BS) acted as moderator. We assessed methodological quality against QUADAS-2 criteria. We extracted binary diagnostic accuracy data from all included studies as 2 x 2 tables. We conducted a bivariate meta-analysis. We used the xtmelogit command in Stata to produce the pooled estimates of sensitivity and specificity and we also produced hierarchical summary ROC plots.

MAIN RESULTS

In the 52 included studies, sensitivity ranged from 41% to 97% and specificity from 52% to 100%. In the seven studies reporting the impact of applying a threshold of 2.5 µg/L, pooled sensitivity was 82% (95% confidence interval (CI) 78% to 86%) and pooled specificity 80% (95% CI 59% to 92%). In the 23 studies reporting the impact of applying a threshold of 5 µg/L, pooled sensitivity was 71% (95% CI 64% to 76%) and pooled specificity 88% (95% CI 84% to 92%). In the seven studies reporting the impact of applying a threshold of 10 µg/L, pooled sensitivity was 68% (95% CI 53% to 79%) and pooled specificity 97% (95% CI 90% to 99%).

AUTHORS' CONCLUSIONS

CEA is insufficiently sensitive to be used alone, even with a low threshold. It is therefore essential to augment CEA monitoring with another diagnostic modality in order to avoid missed cases. Trying to improve sensitivity by adopting a low threshold is a poor strategy because of the high numbers of false alarms generated. We therefore recommend monitoring for colorectal cancer recurrence with more than one diagnostic modality but applying the highest CEA cut-off assessed (10 µg/L).

Progress in metastatic colorectal cancer: growing role of cetuximab to optimize clinical outcome

The prognosis of metastatic colorectal cancer remains poor despite advances made in recent years, particularly with new treatments directed towards molecular targets. Cetuximab, a chimeric immunoglobulin (Ig)G1 monoclonal antibody that targets the ligand-binding domain of the epidermal growth factor receptor (EGFR), is active in metastatic colorectal cancer. As an IgG1 antibody, cetuximab may exert its antitumour efficacy through both EGFR antagonism and antibody-dependent cell-mediated cytotoxicity. The benefits of cetuximab in metastatic colorectal cancer are well documented in clinical trials and are acknowledged in the approval and licensing of this agent. There is evidence of the role of cetuximab not only in irinotecan-refractory or heavily pretreated patients, but also of the efficacy and safety of the addition of this agent to FOLFIRI (irinotecan/5-fluorouracil/leucovorin) in first-line metastatic colorectal cancer, with an enhanced effect in 5-fluorouracil patients with Kirsten rat sarcoma (KRAS) wild-type tumours. In these patients, a recent meta-analysis of the pooled Cetuximab Combined with Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer (CRYSTAL) and Oxaliplatin and Cetuximab in First-Line Treatment of mCRC (OPUS) patient populations confirms that the addition of cetuximab to first-line chemotherapy achieves a statistically significant improvement in the best overall response, overall survival time, and progression-free survival (PSF) compared with chemotherapy alone. In nonresectable colorectal liver metastases, cetuximab plus FOLFOX-6 (oxaliplatin/5-fluorouracil/leucovorin) or cetuximab plus FOLFIRI increased significantly resectability of liver metastases, including R0 resections. Also, preliminary data indicate that cetuximab can be administered in a more convenient 2-week schedule in combination with standard chemotherapy. Cetuximab is generally well tolerated. Acne-form rash is the most frequent toxicity. Up to the present time, the results obtained with targeted therapy combinations are not as encouraging as initially expected. The identification of biomarkers associated with disease control, including KRAS and BRAF mutation status in patients treated with cetuximab, is changing the current management of metastatic colorectal cancer. Clinical and molecular predictive markers of response are under active evaluation in order to better select patients who could benefit from cetuximab treatment, with the aim of both optimising patient outcomes and avoiding unnecessary toxicities.

Carcinoembryonic Antigen in the Staging and Follow-up of Patients with Colorectal Cancer

CEA is a complex glycoprotein produced by 90% of colorectal cancers and contributes to the malignant characteristics of a tumor. It can be measured in serum quantitatively, and its level in plasma can be useful as a marker of disease. Because of its lack of sensitivity in the early stages of colorectal cancer, CEA measurement is an unsuitable modality for population screening. An elevated preoperative CEA is a poor prognostic sign and correlates with reduced overall survival after surgical resection of colorectal carcinoma. A failure of the CEA to return to normal levels after surgical resection is indicative of inadequate resection of occult systemic disease. Frequent monitoring of CEA postoperatively may allow identification of patients with metastatic disease for whom surgical resection or other localized therapy might be potentially beneficial. To identify this group, serial CEA measurement appears to be more effective than clinical evaluation or any other diagnostic modality, although its sensitivity for detecting recurrent disease is not as high for locoregional or pulmonary metastases as it is for liver metastases. Several studies have shown that a small percentage of patients followed postoperatively with CEA monitoring and who undergo CEA-directed salvage surgery for metastatic disease will be alive and disease-free 5 years after surgery. Furthermore, CEA levels after salvage surgery do appear to predict survival in patients undergoing resection of liver or pulmonary metastases. However, several authors argue that CEA surveillance is not cost-effective in terms of lives saved. In support of this argument, there is no clear difference in survival after resection of metastatic disease with curative intent between patients in whom the second-look surgery was performed on the basis of elevated CEA levels and those with other laboratory or imaging abnormalities. There is also no clear consensus on the frequency or duration of CEA monitoring, although the ASCO guidelines currently recommend every 2-3 months for at least 2 years after diagnosis. In the follow-up of patients undergoing palliative therapy, the CEA level correlates well with response, and CEA is indicative of not only response but may also identify patients with stable disease for whom there is also a demonstrated benefit in survival and symptom relief with combination chemotherapy. More recently, scintigraphic imaging after administration of radiolabeled antibodies afforded an important radionuclide technique that adds clinically significant information in assessing the extent and location of disease in patients with colorectal cancer above and beyond or complementary to conventional imaging modalities. Immunotherapy based on CEA is a rapidly advancing area of clinical research demonstrating antibody and T-cell responses.

Diagnostic precision of carcinoembryonic antigen in the detection of recurrence of colorectal cancer

INTRODUCTION

The aim of the study was to evaluate the diagnostic precision of serum carcinoembryonic antigen (CEA) in the detection of local or distant recurrence following resectional surgery for colon and rectal cancer.

METHODS

Quantitative meta-analysis was performed on 20 studies, comparing serum CEA with radiological imaging and/or pathology in detecting colorectal cancer (CRC) recurrence in 4285 patients. The cut-off for a 'positive' CEA ranged from 3 to 15 ng/ml between the various studies. Sensitivity, specificity and diagnostic odds ratio (DOR) were calculated for each study. Summary receiver operating characteristic curves (SROC) and sub-group analysis were undertaken.

RESULTS

The overall sensitivity and specificity of CEA for detecting CRC recurrence was 0.64 (95% CI: 0.61-0.67) and 0.90 (95% CI: 0.89-0.91), respectively. The area under the SROC curve was 0.75 (SE=0.04) and the diagnostic odds ratio was 18.44 (95% CI: 11.94-28.49). A CEA cut-off of 5 ng/ml yielded a higher diagnostic odds ratio than a cut-off of 3 ng/ml (15.5 vs. 11.1). Using meta-regression analysis the optimum CEA cut-off point for the best combination of sensitivity and specificity was 2.2 ng/ml. On sub-group analysis high quality studies, and those involving > or =100 patients yielded a marginal improvement in the sensitivity and specificity with minimal change to the SROC.

CONCLUSION

Serum CEA is a test with high specificity but insufficient sensitivity for detecting CRC recurrence in isolation. A cut-off of 2.2 ng/ml may provide an ideal balance of sensitivity and specificity. It may be useful as a first-line surveillance investigation in patients during surgical follow-up based on serial CEA measurements using temporal trends in conjunction with clinical, radiological and/or histological confirmation.

Follow-up of patients with colorectal cancer: numbers needed to test and treat

Follow-up after curative treatment of patients with colorectal cancer has as its main aims the quality assessment of the treatment given, patient support, and improved outcome by the early detection and treatment of cancer recurrence. How often, and to what extent, the final aim, improved survival, is indeed realised is so far unclear. A literature search was performed to provide quantitative estimates for the main determinants of the effectiveness of the follow-up. Data were extracted from a total of 267 articles and databases, and were aggregated using modern meta-analytic methods. In order to provide one more colorectal cancer patient with long-term survival through follow-up, 360 positive follow-up tests and 11 operations for colorectal cancer recurrence are needed. In the remaining 359 tests and 10 operations, either no gains are achieved or harm is done. As the third aim of colorectal cancer follow-up, improved survival, is realised in only few patients, follow-up should focus less on diagnosis and treatment of recurrences. It should be of limited intensity and duration (3 years), and the search for preclinical cancer recurrence should primarily be performed by carcino-embryonic antigen (CEA) testing and ultrasound (US). The focus of colorectal cancer follow-up should shift from the early detection of recurrence towards quality assessment and patient support. As support that is as good or even better can be provided by a patient's general practitioner (GP) or by specialised nursing personnel, there is no need for routine follow-up to be performed by the surgeon.

Tumor angiogenesis predicts recurrence with normal serum carcinoembryonic antigen in advanced rectal carcinoma patients

Many studies have established the usefulness of serum carcinoembryonic antigen (CEA) oriented serial monitoring for predicting recurrence and prognosis; however, few studies have so far investigated serum CEA-negative recurrence. The aim of this study was to elucidate the nature of CEA-negative recurrence regarding tumor angiogenesis. Fifty-seven patients with T3/T4 rectal cancer were divided into the two groups according to the serum CEA status. Angiogenesis was defined as the intratumoral vessel count by immunohistochemical staining using CD31. The CD31 count was significantly higher in the recurrent patients in both groups and the ratio of nodal involvement was significantly higher in the recurrent patients of the CEA-negative group. Local recurrence mainly developed in the CEA-negative group; however, the CD31 count did not predict the sites of recurrence nor the relapse period in the both groups. A multivariate analysis showed a high CD31 count >26) to be a prognostic factor not only for recurrence but also for survival (P = 0.001, 0.043, respectively). These results suggest that a high degree of tumor angiogenesis in sections of T3/T4 rectal cancer may therefore be an important predictor for CEA-negative recurrence.