Cancer

cancer Cancer is a disease of uncontrolled cell division. It starts with a single cell that loses its control mechanisms due to a genetic mutation. That cell starts dividing without limit, and eventually kills the host.

cancer The genetic material DNA of a cell can become damaged or changed This is called a mutation.

The Code of Life… A T C G T A T G C G G… The “code” of the DNA is the SPECIFIC ORDER in which the bases occur. A T C G T A T G C G G…

What causes mutations? Exposure to radiation Chemicals such as those found in cigarette smoke. Spontaneous - as a result of mistakes that are made when DNA duplicates prior to cell division.

Normal cells are controlled by several factors Normal cells stay in the G1 stage of the cell cycle until they are given a specific signal to enter the S phase. Cancer cells enter the S phase without waiting for a signal.

Normal cells are controlled by several factors. Normal cells are mortal. This means that they can divide about 50 times and then they lose the ability and die. Cancer cells escape this process of mortality: they are immortal and can divide endlessly.

Normal cells are controlled by several factors. Normal cells that suffer significant chromosome damage will self-destruct due to the action of a gene called “p53”. Cancer cells either lose the p53 gene or ignore its message and fail to destroy themselves.

Genetics of Cancer Only a small number of the approximately 35,000 genes in the human genome have been associated with cancer. Alterations in the same gene often are associated with different forms of cancer.

Genetics of Cancer These malfunctioning genes can be broadly classified into three groups. Proto-oncogenes Tumor suppressor genes DNA repair genes

Genetics of Cancer Proto-oncogenes produce protein products that affect cell division or cell death.

Genetics of Cancer The mutated forms of these genes are called oncogenes.

Genetics of Cancer Tumor suppressor genes make proteins that normally prevent cell division or cause cell death.

Genetics of Cancer Controlled cell growth is maintained by regulation of proto-oncogenes, which accelerate growth, and tumor suppressor genes, which slow cell growth.

Genetics of Cancer Proto-oncogenes and tumor suppressor genes work much like the accelerator and brakes of a car, respectively.

Genetics of Cancer Mutations that produce oncogenes accelerate growth while those that affect tumor suppressors prevent the normal inhibition of growth. In either case, uncontrolled cell growth occurs.

Genetics of Cancer DNA repair genes help prevent mutations that lead to cancer.

Cancer progression Once a single cell starts growing uncontrollably, it forms a tumor, a small mass of cells. No further progress can occur unless the cancerous mass gets its own blood supply. “Angiogenesis” is the process of developing a system of small arteries and veins to supply the tumor. Most tumors don’t reach this stage.

Cancer progression A tumor with a blood supply will grow into a large mass. Eventually some of the cancer cells will break loose and move through the blood supply to other parts of the body, where they start to multiply. This process is called metastasis. It occurs because the tumor cells lose the proteins on their surface that hold them to other cells.

Characteristics of cancer cells

Skin Cancer Most common form of cancer. More than 3.5 million cases affecting more than two million people each year, Early detection and treatment are key, which is why it's vital to pay attention to moles and other marks on your skin.

Skin Cancer Three main kinds of skin cancer: Basal cell carcinoma, Squamous cell carcinoma. Melanoma. In addition, there are "precancers" called actinic keratoses, along with iffy moles (dysplastic nevi) that should be watched closely.