Cancer: what is it?
cancer is a dreadful disease, often perceived as “the worst disease.” It is the leading cause of death before age 65 in Canada and France. Nowadays, more and more people are diagnosed with cancer, but fortunately many are recovering.
There are more than a hundred varieties of cancer, or malignant tumor , that can lodge in different tissues and organs.
In people with cancer , some cells multiply in an exaggerated and uncontrolled way. The genes of these disordered cells have undergone alterations, or mutations. Sometimes cancer cells invade surrounding tissues, or become detached from the original tumor and migrate to other areas of the body. These are the ” metastases “.
Most cancers take several years to form. They can appear at any age, but are more often found in people over 60 years of age.
Note . The benign tumors are not cancer: they are not likely to destroy nearby tissue and spread in the body. They can, however, put pressure on an organ or tissue.
The body has a panoply of tools to repair the genetic “mistakes” or to destroy the potentially cancerous cells. However, sometimes these tools are defective for one reason or another.
Several factors can accelerate or cause the emergence of cancer. Moreover, it is believed that it is most often a set of risk factors that leads to cancer. The age is an important factor. But nowadays, about two – thirds of cancer cases are attributable to lifestyle habits , mainly smoking and eating. Exposure to carcinogens in the environment (air pollution, toxic substances handled at work, pesticides, etc.) also increases the risk of cancer. Finally, hereditary factors are responsible for 5% to 15% of cases.
- About 45% of Canadians and 40% of Canadian men will develop cancer during their lifetime.
- According to the National Cancer Institute, in 2011, there were 365,500 new cases of cancer in France. That same year, the number of cancer-related deaths was 147,500.
- One in four Canadians will die of cancer, regardless of gender. Lung cancer is responsible for more than a quarter of all cancer deaths.
- More cases of cancer are diagnosed than before, partly because of the aging of the population and because it is more
|Cancer around the world
The most common types of cancer vary from region to region. In Asia , cancers of the stomach, esophagus and liver are much more frequent, especially because the diet of the inhabitants includes a large portion of very salty, smoked and pickled foods. In sub-Saharan Africa , cancers of the liver and cervix are widespread because of the hepatitis viruses and human papillomavirus (HPV). In North America as well as in Europe , lung, colon, breast and prostate cancers are the most common, due to smoking, poor eating habits and obesity. In JapanRed meat consumption, which has increased steadily over the last 50 years, has increased the incidence of colon cancer by 7 times. Emigrants generally end up having the same diseases as the population of their host country.
No doctor can predict with certainty the course of cancer or the chances of survival for a particular person. Statistics on survival rates, however, give some idea of how the disease is changing in a large group of people.
A significant proportion of patients permanently cure cancer. According to a large survey conducted in France, more than 1 patient in 2 is still alive 5 years after receiving the diagnosis.
The cure rate depends on a multitude of factors: the type of cancer (the prognosis is excellent in cases of thyroid cancer, but is much less in case of pancreatic cancer), the extent of cancer in the time of diagnosis, cell malignancy, availability of effective treatment, etc.
|The most commonly used method for determining the severity of a cancer is the TNM classification (Tumor, Node, Metastase), for “tumor”, “ganglion” and “metastasis”.
How cancer appears
Cancer usually takes several years to develop, at least in adults. We distinguish 3 stages:
- Initiation . The genes in a cell are damaged; this happens frequently. For example, carcinogens in cigarette smoke can cause such damage. Most of the time, the cell repairs the error automatically. If the error is irreparable, the cell dies. This is called apoptosis or cellular suicide. When the repair or destruction of the cell is not done, the cell remains damaged and goes to the next step.
- Promotion . External factors will stimulate or not the formation of a cancer cell. These may include lifestyle habits, such as smoking, lack of physical activity, poor nutrition, etc.
- Progression . The cells proliferate and the tumor is formed. In some cases, they can invade other parts of the body. In its growth phase, the tumor begins to cause symptoms: bleeding, fatigue, etc.
|Characteristics of a cancer cell
Transformations that occur in the genes of the cell, when it becomes cancerous, are transmitted to its descending cells.
The different cancers
Each type of cancer has its characteristics and its own risk factors. Please refer to the following sheets for more details on these cancers.
- Cervical cancer
- Colorectal cancer
- Cancer of the endometrium (uterine body)
- Cancer of the stomach
- Cancer of the liver
- Cancer of the throat
- Cancer of the esophagus
- Cancer of the pancreas
- Skin Cancer
- Lung Cancer
- Prostate Cancer
- Breast Cancer
- Testicular Cancer
- Thyroid Cancer
- Bladder Cancer
- Non-Hodgkin’s Lymphoma
- Hodgkin’s Disease
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