By Nimer G. Shaheen, MD, PhD, FACS, Director Surgeon of General Laparoscopic Surgery, Surgical Oncology, Athens Medical Center
Cancer markers are substances that help in early diagnosis (detection), in the distinction between benign and malignant neoplasms, in the monitoring of metastases and in the evaluation of treatment.
Thus, it is possible to detect the recurrence of the disease before it is too late, as possible metastases are screened before clinical symptoms even occur.
What are cancer markers?
Tumor markers are substances that are found in cancerous cells or are produced by normal cells in response to the presence of a tumor, but with a higher concentration and, in any case, above normal levels. Cancer markers are detected in biological fluids (blood, etc.) These markers can detect a tumor before it even manifests clinical symptoms or before cancer is diagnosed by other clinicopathological methods and early diagnosis allows for more effective treatment.
The existence and especially the increase of their concentration above normal limits is related to the presence, development, diagnosis or even prognosis of a malignant tumor.
Various other substances are also considered as cancer markers, such as hormones, antigens, enzymes, proteins, etc. It is worth noting that there are cancer markers that are specific to each cancer, such as breast cancer, cancer of the ovaries and others.
These substances appear in blood circulation:
- because they are produced from cancer cells and are in a very low concentrations
- or are physiological substances that are produced by tissues and because of cancer at a particular point of the body appear on the blood circulation.
In both cases it concerns antigens associated to tumors and are produced by oncogenic cells, but also from some embryonic or normal cells. The difference is quantitative, as in the case of cancer the concentration is much greater than in healthy individuals.
What is the practical use of cancer markers?
An increased indication does not signify definite cancer, but it is a cause for worry and further investigation on the patient.
What is certain, though, is the fact that the markers help monitoring cancer patients, in cases of e.g. surgery, chemotherapy, radiation therapy, recurrences or metastases, in which we have big changes. An increase or a continuous increase of cancer markers often indicates recurrence, metastasis and small response to treatment, while reduced levels indicate a positive response, therefore a good prognosis.
Conclusion
By measuring cancer markers in biological fluids of patients we can achieve the following:
- early diagnosis
- differential diagnosis
- appreciation of the nature and the size of the tumor
- tumor evolution and prognosis
- assessment of area and staging of tumor evaluation
- treatment effectiveness evaluation
- monitoring for the purpose of early detection of recurrence of the disease
- metastatic check before the appearance of clinical symptoms
