Cancer is a dreaded disease, often perceived as “the worst disease”. It is the leading cause of death before the age of 65, in Canada and France. Nowadays, more and more people are diagnosed with cancer, but fortunately many are recovering.
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. 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 women will develop cancer during their lifetime82.
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 the deaths caused by cancer.
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 one region of the globe to another. In Asia, cancers of the stomach, esophagus and liver are much more common, especially because the diet of the inhabitants includes a large portion of very salty, smoked and pickled foods. In sub-Saharan Africa, liver and cervical cancer 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 Japan, the consumption of red meat, which has steadily increased over the last 50 years, has increased the incidence of colon cancer by 7 times3. Emigrants usually end up having the same diseases as the population of their host country3,4.
No doctor can predict with certainty the course of cancer or the chances of survival for any one person. Statistics on survival rates, however, give someidea 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 5years after receiving the diagnosis1.
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 inthetimeofdiagnosis,cellmalignancy, 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”.
- Stage T (1 to 4) describes the size of the tumor.
- Stage N (from 0 to 3) describes the presence or absence of metastases in neighboring ganglia.
- Stage M (0 or 1) describes the absence or the presence of metastases at a distance from the tumor.
How cancer appears
Cancer usually takes several years to develop, at least in adults. There are 3 stages3:
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.
The different cancers
Each type of cancer has its characteristics and its own risk factors.
- Cervical cancer
- Colorectal cancer
- Cancer of the endometrium (body of the uterus)
- Stomach cancer
- Liver cancer
- Throat cancer
- Cancer of the esophagus
- Pancreatic cancer
- Skin cancer
- Lung cancer
- Prostate cancer
- Breast cancer
- Testicular cancer
- Thyroid cancer
- Bladder cancer
- Non-Hodgkin’s lymphoma
- Hodgkin’s diseas