Tumor or cancer is a pathological cell masses caused by abnormal and uncontrolled cell division of single cell. The transformation of normal cell to tumor cell can be due to spontaneous mutation by environmental factors such as radiation, chemical etc or induced by physical carcinogen viruses.
Local invasion happen where the tumour cells grow and become bigger in local place. The tumour growth suppress the neraby cells. It will squeeze and block small blood vessels in the area. Consequence, it cause the low supply oxygen and nutrient to the normal cells. The normal cells eventually die. A tumor is not capable of indefinite growth and does not invade the healthy surrounding tissue extensively is called benign. While, a tumor grow and become progressively invasive is called malignant or cancer. Cancer cells able to spread to other tissues via blood circulation or lymph which is called metastasis.
The tumor cells become antigenically foreign/different from the normal cells. Immune defense system recognize the non-self antigen and destroy them either in innate immunity or adaptive adaptive.
Tumor cells may express antigens that are specific as below:
|CA 125||Ovarian cancer|
|CA 153||Breast cancer|
|Carcinoembryonic antigen (CEA)||Colon cancer|
|Prostate specific antigen (PSA)||Prostate cancer|
Tumor antigens are used as tumor marker to detect and monitor the tumor or cancer and can be detected using immunoassay.
Several types of cancer immunotherapy such as:
1. Manipulation of Co-Stimulatory Signals Can Enhance Immunity
Providing the co-stimulatory signal necessary for activation of CTL precursors.
Example: B7-transfected tumor cells to induce differentiation into effectoc CTLs which mediate tumour cell destruction.
Transfection of tumor cells with the gene encoding granulocyte macrophage colony-stimulating factor (GM-CSF) allows the tumor cells to secrete high levels of GM-CSF.
This cytokine will activate dendritic cells in the vicinity of the tumor, enabling the dendritic cells to present tumor antigens to both Th cells and Tc cells
- Recombinant cytokines – cloning of various cytokines.
4. Monoclonal Antibodies
- Example: anti-idiotype monoclonal antibodies have been used with some success in treating human B-cell lymphomas and T-cell leukemias.