6.1 NEED FOR THE STUDY
Cancer is the second most common cause for death in developed countries, second only
to cardiovascular diseases. In males, cancers of oral cavity, lungs, colon and rectum, pharynx and
esophagus are the most common while in females, cancers of cervix, colon and rectum, and breast are
most common.Cancer is a significant cause of mortality and morbidity throughout the world. Eleven
million new cases of cancer are diagnosed every year.
It is estimated that there are approximately 2-2.5 million cases of cancer in India at any
given point of time with around 7,00,000 new cases being detected every year. 1 Early detection of
cancer is essential for providing treatment to improve quality of life and prevent mortality and
morbidity. Search is on for ideal tumor markers.
Tumor markers are the substances released from the tumor cells, which could be detected
in bloodand therefore indicate the presence of the tumor in the body. They are useful for screening,
diagnosis, prognosis, and management of cancer.2 Tumor marker requests are increasing in the hospitals
due to availability of automated assays and reduced turnaround time for these assays. However,these
assays are relatively expensive and it is necessary to use them judiciously. It is also important to know
that none of the tumor markers are ideal and 100% specific. Elevations of tumor markers are seen in
clinical conditions other than cancer which should be considered when interpreting the results of tumor
marker assays. 2,3 In our tertiary care hospital with a dedicated oncology department large number of
tumor marker requests come to the clinical biochemistry laboratory which has the automated
chemiluminescence facility for assaying tumor markers. This study is taken up to evaluate the nature of
tumor marker requests and follow up the clinical utility of these assays in our hospital.
6.2 REVIEW OF LITERATURE
An ideal tumor marker should have high sensitivity, specificity, accuracy and precision. It should
have 100 % accuracy in differentiating between healthy individuals and tumor patients. A tumor marker
should be able to differentiate between neoplastic and non-neoplastic disease and show positive
correlation with tumor volume and extent. It should predict recurrence and have prognostic value. It
should be easily assayable and be able to indicate all changes in cancer patients receiving treatment.
Unfortunately none of the tumor markers reported to date have above ideal characteristics. Tumor
markers may be tumor associated antigens, hormones, enzymes and metabolites. 2,3
Alpha-Feto protein (AFP) is an onco- foetal antigen .AFP is synthesized in liver ,yolk sac and
gastro intestinal tract in foetal life and is released in to the serum of foetus . It is a normal component
of serum protein in human foetal life and in normal adults it is negligible . AFP is the most specific and
ideal tumors marker for primary carcinoma of the liver(hepatocellular carcinoma) . AFP as tumor
marker has been found to be also most useful in germ cell tumors of the testes and ovary ,it is also a
best available tumor markers for germ cell type of tumors .AFP is specifically elevated in embryonal
carcinoma and yolk sac tumor .2
Human Chorionic Gonadotropin (HCG) is a placental hormone synthesized by
syncytiotrophoblastic cells of placental villi. Normally ,it is present in the serum of non pregnant
women in very trace amounts ornot at all .But it is markedly elevated in pregnancy .measurement of
elevated HCG in serum and urine has been used to diagnose pregnancy .β-HCG is an ideal tumor
marker for diagnosis and monitoring gestational trophoblastic tumors and germ cell tumors of testes and
ovary . β-sub unit of HCG is typically measured because of its increased specificity and because some
tumors secrete only β sub unit .2
Cancer antigen 15-3 (CA 15-3) is an carbohydrate antigen .It has been found useful as tumor marker
in breast carcinoma. CA 15-3 is can be detected by monoclonal antibody generated against extracts of
metastatic human breast cancer . Elevated CA 15-3 levels are found in 70-80% of patients with
metastatic or recurrent breast cancer .Important role of CA 15-3 is early detection of recurrence .Most
studies have shown that CA 15-3 level is a more sensitive marker than the CEA level . 2
Cancer antigen 125 (CA 125) is a carbohydrate antigen ,used as an antigenic determinant expressed
by epithelial ovarian carcinomas. It has been used for screening and diagnosis of ovarian carcinoma
.An elevated CA 125 level is observed in 80-90% patients with ovarian cancer .the elevation correlates
well with tumor size and stage .CA 125 is not specific for ovarian carcinoma. 2
6.3OBJECTIVES OF THE STUDY
1. To study the requests for assays of β-HCG,AFP,CA-125,CA-15.3 with respect to the requesting
department and site of cancer .
2. To assess the clinical usefulness of the tumor marker requests with respect to diagnosis, prognosis
and follow up .
7.MATERIALS AND METHODS
7.1 SOURCE OF DATA
All the tumor marker requests coming to Clinical Biochemistry Laboratory of Father Muller Medical
College and Hospital, Mangalore for a period of one year in 2011-12.
7.2 METHOD OF COLLECTION OF DATA
As`per the request from the clinician, the tumor markers β-HCG,AFP,CA-125,CA-15.3 will be assayed
byelectrochemiluminescence method in automated Roche Elecsys – equipment. The results will be
later correlated with clinical findings and details from the case files. Purpose of asking for tumor
marker assay, and clinical usefulness of the assay will then be evaluated.
7.3 Does the study require any investigations or interventions to be conducted on patients or other
humanor animal?
No
7.4 Has ethical clearance been obtained from your institution in case of 7.3?
Yes
8.LIST OF REFERENCES
- Park K. Park’s Text Book of Preventive and Social Medicine, 19th edition,
- Malathi T. Tumor markers : an overview. Indian J Clin Biochem 2007; 22 : 17-31.
- Vasudevan DM, Sreekumari S, Vaidyanathan K. Textbook of Biochemistry for Medical Students, 6th Edition. Jaypee Brothers : New Delhi; 2011; pp. 567-580.