Cancer: what is it?
Cancer is often perceived as an incurable disease, without issue, though, thanks to early detection and treatment, many patients recover.
Tissues and organs are composed of millions of cells. In people with cancer, the body is attacked by cells that multiply in an exaggerated way and invade surrounding tissues. Sometimes, some of them can break off and migrate to other parts of the body Various factors, such as radiation, carcinogens in food, air and cigarette smoke, or genetic predisposition may affect the “mechanics” of these normal cells and prevent them from functioning smoothly. Sick, they will begin to proliferate without control. Normally, the immune system eliminates or prevents them from becoming true tumors, but sometimes these cells thwart our defense mechanisms.
Note that the expressions of malignancy and cancer are also used to describe cancer. The benign tumor is not cancerous, and is less health. It can put pressure on an organ or tissue, but in a limited space and does not spread in the body.
Prevalence
The increasing prevalence of cancer is partly explained by the fact that longevity is increasing and that it detects more cancers than previously, thanks to screening tools. These factors explain about one third of this increase, estimated.
More and more children and adolescents are affected by cancer: a large study conducted in Europe shows that over the last 30 years, cancer incidence increased by 1% per year among children and 1.5% among adolescents.
Prognosis
No doctor can predict with certainty the course of the cancer or the chances of survival for a particular person. Available statistics give an idea of the prognosis for a large group of people, but we can not translate these figures to an individual.
However, a significant proportion of patients permanently cured of cancer. The cure rate depends on many factors: the type of cancer (to where the tumor arose), the extent of cancer at diagnosis, the malignant cells, the presence or bsence of metastases, the availability of effective treatment, etc..
The method of determining the seriousness of cancer is the TNM classification (Tumor, Node, Metastases), for “tumor”, “node” and “metastasis”.
* The T stage (1 to 4) describes the size of the tumor. * The N stage (0 to 3) described the presence or absence of metastases in lymph nodes neighbors. * The M stage (0 or 1) describes the absence or presence of metastases at a distance from the tumor.
Causes
According to public health authorities, two thirds of all cancers are caused by lifestyle, mainly by smoking and poor diet. Hereditary factors were responsible for only 5% to 15% of cancers. In developing countries, the incidence of cancer increases rapidly after the industrialization and the adoption of a lifestyle in the West. Note that some experts hold a different view and pollution as a
major cause of cancer
Lifestyle: Looking World Lifestyle habits play a predominant role in the development of cancer. This is highlighted by the phenomenon of immigration. The migrants usually end up having the same diseases as the population of their country of accueil.Furthermore, the types of cancer most frequently vary from one region to the globe. In Asia, cancer of the stomach, esophagus and liver are much more frequent, particularly because the power of people has a lot of very salty foods, smoked and marinated. In North America and Europe, lung cancer, colon, breast and prostate are the most common, not least because of smoking, poor eating habits and obesity.
In Japan, consumption of red meat, which had increased steadily over the past 50 years, has increased seven times the incidence of cancer côlon.
Formation of a cancer
Cancer can form in any tissue. In adults, it usually develops over several years, even decades. We can divide the formation of a malignant tumor in three steps
* Initiation. The genetic material of a cell is damaged and is a frequent event. Cigarette smoke, asbestos, carcinogenic substances present in foods or a surplus of free radicals can cause such damage. Most of the time, the body repairs the error through to its natural mechanisms. If the error is irreparable, the cell dies. This is known as apoptosis or “suicide” cell. When these mechanisms do not work, the damaged cell in step between “promotion”.
* Promotion. External factors will stimulate or not the formation of a tumor cell. These may be lifestyle, such as smoking, physical activity, nutrition, etc..
* Progression. The cells proliferate and the tumor is formed. In some cases, they may invade other parts of the body. In its growth phase, the tumor begins to cause symptoms: bleeding, fatigue, etc..
The properties of cancer cells and tumor
* A disorderly proliferation. The cells reproduce continually and are insensitive to stop signals from growth of neighboring cells.
* A loss of original function. The cells are no longer useful to the organism.
* Immortality. The process of apoptosis or “suicide” cell, which normally is triggered when a
cell is disturbed, no longer works.
* Resistance to attack the immune system. Cancer cells circumvent their “murderers”, NK cells and other cells supposed to limit their progression.
* The formation of new blood vessels, called angiogenesis. These vessels are essential to the growth of tumors, because they provide nutrients and oxygen (if not, tumors can not grow beyond 1 mm)
* Often, the invasion of neighboring tissues and other body parts. The new outbreaks of cancer are called metastases.
The genetic changes that occur in the cell, when it becomes cancerous, are passed down to his cell.
Various cancers
Each type of cancer has its own characteristics and risk factors. Please refer to the following specific cards for details on these cancers.
- Colorectal cancer (colon and rectum)
- Cancer of the endometrium (uterine body)
- Skin Cancer
- Lung Cancer
- Prostate cancer
- Breast cancer
- Testicular Cancer