CANCER : CANCER A WRENCHING PAIN
WHAT IS CANCER? : WHAT IS CANCER? CANCER is a class of diseases or disorders characterized by uncontrolled division of cells Cancer Classification & external resources
TYPES OF CANCER : TYPES OF CANCER Tumors can be :
BENIGN :Cells remain confined to the tissue of their origin. OR
MALIGNANT :Cells are not enclosed in any specific tissue.They kill other cells and are carried by lymph or blood to other parts of the body.i.e. cells METASTASISE
Types of cancer : Types of cancer On the basis of location cancer is of four types :
1.Lymphoma;e.g. Hodgkin’s disease
2.carcinoma;e.g. lung cancer, breast cancer
3.sarcoma;e.g.bone,muscle,lymph-node cancer
4.leukemia;e.g. blood cancer
CANCER CELLS DIFFER FROM NORMAL CELLS! : CANCER CELLS DIFFER FROM NORMAL CELLS! In two important ways:
1.uncontrolled growth .i.e.unrestricted division of cells.
2.have the ability to METASTASISE .i.e.having the ability to spread from their original site to other locations in the body
CAUSES OF CANCER : CAUSES OF CANCER Cancer can be caused by a variety of factors acting singly or in concert.
Cancer can be caused by :
1.Environmental factors
2.Gene mutations
3.Translocation of chromosomes
1. ENVIRONMENTAL FACTORS : 1. ENVIRONMENTAL FACTORS Exposure to chemicals as asbestos , polycyclic-hydrocarbons & several compounds contained in cigarette-smoke can cause cancer.
Ionizing-radiations from sources as X-ray , radioactive fallout & ultra-violet rays are known to be carcinogenic.
GENE MUTATIONS : GENE MUTATIONS 1.DISRUPTION OF CELL CYCLE : Protein kinases(enzymes) & cyclins(proteins),control progression of cells through cell cycle.A mutation in genes controlling these enzymes & proteins could disrupt cell cycle in such a way that control over cell cycle is lost .This would lead to rapid proliferation of cells and hence cancer .
2.PROTO-ONCOGENES : 2.PROTO-ONCOGENES
2.1.Proto oncogenes >>> oncogenes>>>cancer : 2.1.Proto oncogenes >>> oncogenes>>>cancer Proto-oncogenes are special kind of genes that regulate cell-cycle.When these are expressed , they promote cell-division.
Therefore,these genes must be inactivated temporarily
But if these genes become permanently switched on then uncontrolled cell division will lead to TUMOUR FORMATION.
NOTE:When these genes are permanently switched on such that they are responsible for cancer they are called ONCOGENES
2.2.Proto oncogenes >>> oncogenes under 2 conditions : 2.2.Proto oncogenes >>> oncogenes under 2 conditions 1.MUTATION in proto oncogenes switches it ON permanently.
2.Certain viruses infect the cell &get integrated into host genome as PROVIRUS.The provirus can switch on the proto oncogenes.
3.TUMOUR SUPPRESSOR GENES : 3.TUMOUR SUPPRESSOR GENES It is class of genes that regulate cell cycle .
Normally they PREVENT cell division.
When these genes become permanently inactivated or lost through mutation,the control over cell division is lost.
Thus,such cells start dividing abnormally causing cancer.
3.2.SOME TUMOUR SUPPRESSOR GENES & THEIR EFFECTS : 3.2.SOME TUMOUR SUPPRESSOR GENES & THEIR EFFECTS p53:mutation in p53 genes causes a wide range of cancers including breast , lung , bladder & colon cancer.
Rb(retinoblastoma):Mutation in these genes causes cancer of EYE.
Apc:Mutation in Apc genes causes INTESTINAL CANCER.
GENE ALTERATIONS & CANCER- AN OVERVIEW : GENE ALTERATIONS & CANCER- AN OVERVIEW
4.TRANSLOCATION OF CHROMOSOMES : 4.TRANSLOCATION OF CHROMOSOMES Changes in structure/number of chromosomes are often associated with various forms of cancer.
One of the best studied examples is translocation b/w chromosome 9 & chromosome 22.
Exchange of genetic material b/w these chromosomes results in Philadelphia chromosome(abnormal chromosome 21) which is associated with cancer of WBCs known as Chronic myelogenous leukemia(CML).
TREATMENT : TREATMENT The earlier cancer is diagnosed,greater are the chances of successful treatment.
The poor success rates in treating cancer are mainly due to lateness of diagnosis.
Current cancer treatment depends on :
1.Drugs
2.Hormones(Chemotherapy)
3.Surgery
4.Radiation therapy
or A combination of these
DISADVANTAGES of treatments of cancer : DISADVANTAGES of treatments of cancer Most chemotherapeutic drugs are designed to attack genetic material of tumour cells but ,these cells are not specific & can also kill normal cells.
In radiation therapy , radiations directed at the cancer may destroy normal tissue.
If a tumour is confined to a distinct area it may be possible to remove it surgically but the cells MUST BE completely removed in order to reduce the risk of developing metastases(secondary tumours)through the migration of cancer cells.
Once a tumour has metastasized to other parts of the body,it is much more difficult to remove metastases surgically,they may be numerous & inaccessible.
Hence chemotherapy may be the only option
THANK YOU : THANK YOU MADE BY :- RENU SHARDA
10+1-D , ROLL NO. 05