Page 7 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

4 CHAPTER 1 Introduction

antibody (mAb) treatment [22]. There are several suggested mechanisms for the
escape of cancer cells from host immunity. These ways include decreased expression
of immunogenic TAAs, beta2-microglobulin, MHC class I molecules, and costimu-
latory molecules which have influence on activation of T cells. Other mechanism is
the expression of very low levels of antigens, unable to induce immune response.
Cancer cells may proliferate rapidly and induce a rapid immune response. Another
mechanism for evade of cancer cells from surveillance of immune system include
of tumor signaling by CTLs, secretion immunosuppressive molecules dampening
tumor-reactive effector T cells and the induction of regulatory or suppressor cells
[23]. So far, direct evidence about tumor-regulated immunity is derived from experi-
mental studies in animal models. These animal models support antitumor immunity
by vaccination using inactive cancer cells or by resection of primary tumors. Fur-
thermore, antitumor immunity can be induced by administration of tumor-reactive T
lymphocytes [24].
Currently, new molecular immunological diagnostic methods for tumor diagnosis
are proposed.
In vivo detection of micro tumors is available by using of monoclonal antibodies
marked with radioisotopes.
In vitro detection of the undifferentiated tumor cell using monoclonal antibodies
is other application of these molecules. Another application of immunodiagnostics
methods is to detection of metastatic cells [25].
There are four general therapeutic approaches in cancer therapy:

1. Chemotherapy, the treatment of disease by the use of chemical substances,
especially the treatment of cancer by cytotoxic and other drugs that interfere
with cell division and DNA synthesis.
2. Hormonal therapy, is a cancer treatment that slows or stops the growth of cancer
that uses hormones to grow and interfere with growth signaling via tumor cell
hormone receptors.
3. Targeted therapy, a type of treatment that using drugs or other substances to
recognize and attack specific types of tumor cells with low damage to normal
cells. Some targeted therapies block the action of certain enzymes, proteins, or
other molecules involved in the growth and metastasis of tumor cells.
4. Immunotherapy, immunotherapy is a type of biological therapy and cancer
treatment that helps immune system fight against cancer. This method uses
substances made from living organisms to treat tumors [26].
Cancer immunotherapy is a novel therapeutic method for cancer treatment, with
promising results. This approach has improved the cancer-related immune response
by either increasing mechanisms of the immune system that induces an effective
immune response or by suppressing mechanisms that inhibit the immune response.
Currently, two approaches are used for immunotherapy including allogeneic bone
marrow transplantation and monoclonal antibodies (mAbs) targeting tumor cells or
T cell checkpoints [27]. Firstly, cancer vaccines have been considered for prevention
and treatment of several cancers [27]. Based on reports, more than 15% of human