Cancer

What is Cancer?

Cancer is a condition characterized by the uncontrolled growth of cells.

• Develops from a single cell that goes awry, but a combination of events must occur before the cell turns into a tumor.

• Process is called clonal growth: replication of a single cell that produces thousands of copies of itself in an uncontrolled manner.

Healthy Cell Growth

Healthy cells have a complicated system of checks and balances that control cell growth and division.

Healthy cells divide when needed to replace cells that have died or been sloughed off.

Each time a cell divides, there is the possibility of mutation or an error in DNA replication.

Stem cells: undifferentiated cells that can give rise to specialized cells.

Because they do not have a predetermined number of cell divisions, they pose a risk of cancer.

Stem cells are located deep within tissues and are protected from factors that increase the risk of genetic mutations (exposure to the sun, chemicals, and irritation).

Cancel Cell Growth

Cancer starts from a single cell that undergoes a critical mutation.

An initiating event in the cell's DNA allows a cell to evade normal cell restraints.

• duplication error.

• Exposure to a carcinogen (cancer-causing substance).

• Radiation.

Escaping all the control mechanisms to become a cancer may take many years.

Oncogene: a gene that drives a cell to grow and divide regardless of signals from surrounding cells.

Tumor: a mass of extra tissue that may form into either a benign or malignant tumor.

• Benign tumor: slow growth, unlikely to spread.

• Malignant tumor: capable of spreading to surrounding tissues.

Metastasis: cancer that has spread from one part of the body to another.

Type of Cancer

Carcinomas: arise from epithelial tissue (skin, lining of the intestines and body cavities, surface of body organs, outer portions of glands).

Sarcomas: arise in connective tissue (bone, tendon, cartilage, muscle, fat tissues).

Leukemias: cancers of the blood that originate in the bone marrow or the lymphatic system.

Lymphomas: cancers that originate in lymph nodes or glands.

Risk Factors for Cancer

The majority of cancers occur as a result of exposure to carcinogens-cancer-causing agents.

Individuals can limit their exposure by adopting protective lifestyle behaviors.

Other measures are beyond individual control and require action by local authorities, the larger society, or even the global community.

• Air pollution, climate change, and access to health insurance.

Family history:

• Family history of cancer alters some cancer screening recommendations.

• Genes interact with environmental exposures and lifestyle behaviors to alter risk.

Lifestyle factors:

• Tobacco use.

• Nutrition and physical activity.

• Overweight and obesity.

• Alcohol consumption.

Social and economic factors:

• Social determinants of health influence risk behaviors, access to health care, and quality of health care.

Environmental factors:

• Sunlight and other sources of ultraviolet radiation.

• Other forms of radiation.

• Chemical and physical carcinogens.

• Infectious agents.

Cancer Treatments

Surgery:

• Remove the cancer, remove the affected organ; it may still be part of the treatment even if the cancer has spread.

Chemotherapy:

• Drug treatment administered to the entire body to kill rapidly dividing cancer cells.

• Also kills rapidly dividing normal cells, including hair, stomach lining, and white blood cells.

Radiation:

• Directed to a specific area; used with surgery or chemotherapy, or to control pain.