The document discusses carcinoembryonic antigen (CEA), an oncofetal antigen utilized as a tumor marker for monitoring cancer treatment and recurrence. It outlines its biological characteristics, diagnostic methods, and the implications of elevated CEA levels in both malignant and benign conditions. Recommendations for CEA testing procedures and the significance of CEA levels in various patient demographics are also highlighted.

1. Serum CEA as Tumour Marker
Saswata Chakraborty | DMLT | Tata Medical Centre Date: 10.03.2023

2. Brief idea of Carcinoembryonic antigen
It is an oncofetal antigen found in the fetal stage (8 to 16 weeks
of gestation) CEA levels normally become very low or disappear after birth
A high level of CEA in adults can be a sign of certain types of
malignant or benign conditions
CEA is a type of Tumour Marker
Monitoring the level of CEA helps the patient in cancer
treatment, primarily in prevention of recurrence.

3. Tumour is an abnormal mass of tissue that results from
excessive cell division that is uncontrolled and progressive
DIAGNOSIS OF TUMOUR
Patient history and Clinical
examination
Imaging: X-Ray,
Ultrasonography, CT, MRI
Biochemical assays:
Laboratory analysis of
Tumour marker
Histological and Cytological
Molecular Method.

4. Tumour Marker
Tumour Marker:
Substances present in the tumour
or produced by the tumour or by
the host.
It provides an information about
biological characteristics of the
tumour.
DIAGNOSIS OF TUMOUR
Patient history and Clinical
examination
Imaging: X-Ray,
Ultrasonography, CT, MRI
Biochemical assays: Laboratory
analysis of Tumour marker
Histological and
Cytological
Molecular Method.

5. Characteristics of an ideal Tumour Marker
High sensitivity and
specificity
• Should be able to differentiate
between malignant and benign
disease
• Should show positive correlation
with tumor volume and extent
Early prediction of
recurrence
Must show indication of
changes in a patient
receiving treatment
Cost effective and easy to
assay in laboratory

6. Potential Uses
Screening
and early
detection of
Cancer
Diagnosis
Determining
the
prognosis
and
effectiveness
of treatment
Detection of
Recurrence
on follow up
treatment

7. Carcinoembryonic Antigen (CEA)
First isolated from human colorectal
cancer (CRC) tissue in 1965 by
Gold and Freedman
It is a Glycoprotein antigen
Found on the cell surfaces and shed
into the circulation
Can be detected in serum and
plasma
Biological reference interval:
<3.8 ng/mL
Circulation half-life: 1-5 days
Elevated in Malignancy Elevated in Benign
Conditions
Colorectal cancer Chronic obstructive
pulmonary disease
Pancreatic cancer Peptic bowel disease
Breast cancer Crohn’s disease
Lung cancer Smoking

8. Laboratory Diagnosis of CEA
Serum in gold top or red top
serum separator tube
Li-heparin, K2-EDTA and
K3-EDTA plasma
Sample Collection:
7 days at 20-25°C
14 days at 2-8 °C
6 months at -20°C (±5°C)
Serum/ Plasma
Storage:
There is no special preparation
needed before giving blood for
the test
Patient Preparation:
Expression of CEA can be up-
regulated by:
 Antineoplastic drugs
 Cytokines
 Protein kinase inhibitors
Drug administration:

9. Laboratory Diagnosis of CEA
Method:
Enzyme linked immunosorbent assay
(ELISA)
Electro-chemiluminescence
immunoassay (ECLIA)
Enzyme-linked fluorescence assay (ELFA)
Immunomagnetic reduction (IMR)
Cobas e 411
Method: ECLIA
Principle: Sandwich
Assay time: 18 mins

10. TEST PRINCIPLE
1st incubation:
10 µL of sample, a Biotinylated
monoclonal CEA-specific
antibody and a Monoclonal
CEA-specific antibody labeled
with a ruthenium complex react
to form a sandwich complex.
2nd incubation:
After addition of streptavidin-
coated microparticles, the
complex becomes bound to the
solid phase via interaction of
biotin and streptavidin.
The reaction mixture is aspirated
into the measuring cell where the
microparticles are magnetically
captured onto the surface of the
electrode.
Unbound substances are then
removed with ProCell/ProCell M.
Application of a voltage to the
electrode then induces
chemiluminescent emission which
is measured by a photomultiplier.

11. Expected Values
All subjects Non-smokers
(past/never
smokers)
Smokers (current)
Age (years) 20-69 40-69 20-69 40-69 20-69 40-69
95th percentile
(ng/mL)
4.7 5.2 3.8 5.0 5.5 6.5
N 352 203 242 154 110 49
Studies with the Elecsys CEA assay were performed on 352 healthy subjects. The
following results were obtained:

12. Calibration and Quality Control
Calibration Quality Control
Controls for the various concentration ranges
should be run individually at least once every
24 hours when the test is in use
Once per reagent kit
Following each calibration
• Calibration must be performed once per
reagent lot using fresh reagent
• After 28 days when using the same
reagent lot
• After 7 days (when using the same
reagent kit on the analyzer)
• Situations where quality control findings
are outside of the defined limits
Renewed
calibration is
recommended
as follows:

13. Quality Control: Level 1
N: 24
Mean: 25.14
SD: 0.57 CV(%): 2.2

14. Quality Control: Level 2
N: 24
Mean: 53.39
SD: 1.32 CV(%): 2.47

15. CEA in management of recurrence
Source: A Review of the Role of Carcinoembryonic Antigen in Clinical Practice

16. CEA in management of Cancer
Source: A Review of the Role of Carcinoembryonic Antigen in Clinical Practice

17. Things to remember
Healthy individuals has a low level of CEA (<5 ng/mL)
CEA level elevates in both Malignant and Benign conditions
Smokers may have an elevated level of CEA
CEA not used for screening or diagnostic purpose
CEA measurements helps to prevent Recurrence of colorectal cancer

18. References
• Colorectal Cancer in India: An Audit from a Tertiary Center in a Low Prevalence Area
• Tumor markers in clinical practice: General principles and guidelines
• Laboratory Testing for Tumour Markers
• Elecsys CEA
• Carcinoembryonic Antigen as a Marker for Colorectal Cancer: Is It Clinically Useful?
• A Review of the Role of Carcinoembryonic Antigen in Clinical Practice

19. Thank You