Page 48 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

46 CHAPTER 3 Immune assay assisted cancer diagnostic

Table 3.1 Biomarkers in cancer screening studies (cancer site).
Tumor marker Cancer site Sample matrix
HE4 Ovary Blood
CEA Ovary, kidney, colon Blood
CA-125 Breast, liver, lung Blood
HER2 Breast
AFP Stomach Blood
CA 15-3 Breast, lung, ovary Blood
β-hCG Germ cell of ovary Blood, urine

There are several ways to reach a cancer diagnosis, including ultrasound, mag-
netic resonance imaging (MRI), X-ray computed tomography (CT), biopsy, and
blood tests for cancer-related markers. Tumor markers are the proteins that have
presented in circulatory system and their elevated levels can indicate the stage of the
cancer. Some of the biomarkers which have been used in recent cancer screening
studies are listed in Table 3.1.
Immunoassay has been known as one of the uppermost analytical techniques and
is widely used in clinical diagnoses and biochemical studies because of its particu-
larly high selectivity and sensitivity [3].
One of the immune system's principal functions is the production of circulating
molecules called antibodies or immunoglobulins (Igs). Each Ig has comprised of a
specific antigenic determinate or epitope (Fig. 3.1). Although an antigen may have
many different epitopes that react with several different Igs, a unique Ig joins with
only one epitope and this epitope (and the antibody's combining site for it) has a size
of about five to seven amino acids.
Anticancer antibodies (polyclonal and monoclonal) have been used since last
time in the diagnosis and therapy of cancer, with major applications having been

FIGURE 3.1 Detection of tumor-associated antigens expressed in cancer cells using
antibody.