Prognostic and Predictive Markers in Early Detection of Different Types of Cancers for Selected Organ Sites

Abstract

Background: Tumor markers are substances that are produced by cancer or by other cells of the body in response to cancer or certain benign (noncancerous) conditions. Tumor markers are used to help detect, diagnose, and manage some types of cancer. Although an elevated level of a tumor marker may suggest the presence of cancer. Aim: The aim of this review is to compare and analyze the present and newer oncogenic markers which help in diagnosis of different types of cancers. Material & Methods: An extensive literature survey was done aiming to compare and compile cancer tests makers required in diagnosis of diseases. Results: Cytoplasmic Proteins, Cell Surface Antigens, Oncofetal Antigens, Receptors, Oncogenes and their metabolic products, Acute-Phase Proteins, Enzymes, Hormones or Tumor associated antigens such as Carcino-Embryonic Antigen (CEA) and Alpha Feto Protein (AFP) are makers for routine analysis whereas several studies have confirmed and consolidated the usefulness of markers such as AFP: Alfa fetoprotein; β-hCG: Beta human chorionic;gonadotropin; CA: Carbohydrate antigen; CEA: Carcinoembryonic antigen; ER: Estrogen receptor; HIAA: Hydroxy indole acetic acid; LDH: Lactate dehydrogenase; PLAP: Placental alkaline phosphatase; PR: Progesterone receptor; PSA: Prostate-specific antigen. Conclusion: There is no ―universal‖ tumor marker that can detect any type of cancer. Further investigation is necessary to define these biomarkers in terms of usefulness in assessing diagnosing various types of cancers. Keywords: Monitoring; Recurrence; Screening; Prognosis; Diagnosis; Response to therapy. Tumor markers are substances that can often be detected in higher than normal amounts in the blood, urine, or body tissues of some patients with certain types of cancer. These substances can be proteins, enzymes, biochemicals, or antigens. Tumor markers may be produced directly by a tumor or by other tissues in response to a tumor, they can be metabolic products, acute-phase proteins, enzymes, hormones or tumor associated antigens such as Carcino-Embryonic Antigen (CEA) and Alpha Feto Protein (AFP).In general, tumor marker levels are lower in early stage disease (but still higher than normal) and higher with advanced disease. Furthermore, their levels decrease in response to treatment and increase when the cancer progresses. Tumor markers are very useful in monitoring the course of a diagnosed malignant tumor, for example pre-treatment and subsequent serial values are essential for the evaluation of the response to the treatment modality with time. 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. Tumor markers are often used to:  Monitor response to treatment—some tests show whether the cancer is responding to treatment  Monitor for progression—in general, an increase in some tumor markers indicates disease progression  Detect recurrence—regular monitoring of some tumor markers during a remission may help detect recurrence