| Ch 5 | Page 2 / 8 | |
| Tumour markers | Main tumour markers | |
This is a glycoprotein of 200 kDa which is present in the alimentary tract, the liver and the pancreas of the foetus between the second and the sixth month of intrauterine life. It is an adhesion molecule of immunoglobulin type, similar to the N-CAM molecules described in the General History Chapter. It is present in minute quantities in normal plasma, it may be increased in digestive, mammary, and ovarian cancers but also for some benign disorders like cirrhosis, pulmonary insufficiency and heavy smoking. Its half-life (time for which half of the CEA disappears from blood) is around 6 to 8 days.
It is a α1-globulin produced by the foetal liver, the intestinal foetal tract and yolk sac. This is a normal protein during foetal life with a role similar to that of albumin in adults. Its level sharply increases during hepatocellular carcinoma and non-seminomatous testicular (or ovarian) tumours (yolk sac tumours). Half-life of AFP is around 5 - 6 days. The absence of a return to a normal very low level after the removal of tumoral testis is a sign of persistent disease (outside the testis).
This hormone is usually produced during pregnancy by the syncytiotrophoblastic cells of the placenta. Its blood level is sharply elevated in placental tumours and non-semininomatous testicular (and ovarian) tumours (choriocarcinoma). It is a glycoprotein similar to FSH or LH and study of its β chain is very useful. The plasmatic half-life of β-HCG is very short (36-48 hours) thus allowing very precise follow-up during treatment.
An elevated value of serum HCG very often provokes uni- or bilateral gynecomastia,
which can be the first symptom worrying the patient (before the increase in
the size of testis which can be either ignored or 'appreciated' before it becomes
disturbing).
This is a thyroid calcium regulating hormone which is specifically increased in medullary thyroid carcinoma, but can also be ectopically secreted in small cell lung carcinoma.
Lung carcinoma, and noticeably small cell lung carcinoma, is often associated with ectopic production of hormones: ACTH, calcitonin, ADH. Generally it only produces fragments of the protein without a clear hormonal function (except for ADH which then produces the Schwartz-Bartter Syndrome with hyponatremia and oedema).
Synthesised by normal prostate cells, they are essentially elevated during metastatic bone disease. Their role, as a marker, has been totally eclipsed by PSA (see below).
Several isoenzymes exist depending on their originating organ: liver, bone, placenta. Their blood level is frequently elevated in the presence of liver or bone metastases. The placental isoenzyme is elevated during certain ovarian or testicular cancers.
This is a muscular enzyme which is elevated (without clear correlation to the tumour mass) in lymphoma, testis cancer and pulmonary metastases.
This enzyme is often elevated in the plasma of patients with small cell lung cancer.
It is a 40 kDa glycoprotein, isolated from seminal fluid, originating from prostate cells. It is a kallicrein enzyme necessary for spermatoid motility. An increase in this marker is quite specific of prostate (benign of malignant) diseases. The sharp decrease in PSA level after radical prostatectomy or curative radiotherapy ensures security as to their efficiency. Its regular elevation after treatment is generally a symptom of local or distant relapse.
The possibility of inducing monoclonal antibody production has led to the research of specific tumour antigens. Homogenates of tumour cells are injected into mice to produce antibodies which are more or less specific of a tissue and potentially of a tumour.
This antigen has been isolated from a cell line of ovarian carcinoma. It is quite useful in treatment follow-up of ovarian cancers. However, as described in the following pages, it is not specific of ovarian tumours.
This is a heavy molecule present in the fat globules of human milk. This molecule is increased in adenocarcinoma of the breast, but also of the ovary and lungs. However, it appears useful in treatment follow-up of breast cancers.
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