Cancer incidence rises to become the 2nd most common cause of death

Cancer is the second most common cause of death after cardiovascular disease and will increase in incidence with increased longevity. Thus, many countries have seen a steady annual increase. Approximately three-quarters of all those who die from cancer are 65 or older. Exceptions include testicular cancer, breast cancer and the childhood cancers (leukaemia, lymphoma, brain tumours and Wilm's tumour).

Tumour markers are proteins found in the blood, tissues or urine that indicate a malignant process is present.  Some are specific to just one type of cancer while others are more general and are found at elevated levels in different types of cancer.

Tumour markers may be produced directly by a tumour or by other tissues in response to a tumour, they can be metabolic products, acute-phase proteins, enzymes, hormones or tumour associated antigens such as Carcino-Embryonic Antigen (CEA) and Alpha Feto Protein (AFP).   When used in combination with x-rays and other tests the detection of tumour markers in the blood can be extremely useful in the detection and diagnosis of cancer.  Although measurement alone is not enough to base a diagnosis on their detection can be important in monitoring severity etc.

The ideal tumour marker would have the following characteristics:

• 100% organ specificity
• 100% accuracy in differentiating between healthy individuals and those with a particular malignant tumour
• The ability to detect all patients with a particular malignancy, and if possible, at a very early stage in the transformation process.
• Excellent correlation between the concentration of the marker and the individual tumour stages including relapse and remission
• Prognostic value of the tumour marker concentration

The first 3 requirements are necessary for use as a screening tool however as yet no such tumour marker fulfils this criteria. Prostatic Specific Antigen comes closest of all the tumour markers and is widely used in the USA to screen for prostatic carcinoma.

Tumour markers are very useful in monitoring the course of a diagnosed malignant tumour, for example pre-treatment and subsequent serial values are essential for the evaluation of the response to the treatment modality with time. Depending on the malignancy, different tumour markers may be expressed and those elevated at the time of diagnosis are the ones that are usually employed for monitoring.

The following proteins have been found at elevated levels in various forms of cancer;

• CEA – Carcinoembryonic antigen is mainly associated with the developing foetus however can also indicate the presence of a tumour. Elevated levels of CEA have been found in a variety of cancers including lung, gastric, pancreatic and breast cancer.  CEA is a useful marker when providing a prognosis as well as monitoring treatment and re occurrence. 

• AFP – alpha-fetoprotein is present at very low levels in healthy individuals, elevated levels have been associated with some cancers e.g. testicular and ovarian.

• hCG – Human chorionic gonadotropin is a hormone produced during pregnancy, it also present in normal healthy individuals at lower levels.  In addition to this it is secreted by some cancers mainly gestational trophoblastic tumours making it a very sensitive tumour marker and ideal for screening and monitoring of treatment. Increased levels have also been noticed in various other cancers e.g. lung and breast cancer. 

Prostate cancer is the second most common cause of cancer in men the following are effective tumour markers for this type of cancer:

• Free and Total prostate specific antigen – PSA is produced by cells of the prostate, in normal healthy individuals concentrations are low however are noticeably elevated in patients with prostate cancer providing a sensitive tumour marker. PSA is tissue specific meeting at least one of the ideal tumour marker characteristics listed above.  It is useful in monitoring both treatment and re occurrence.

Randox provide arrays containing all of the above mentioned tumour markers, for more information please visit the Biochip immunoassays section of our website.