Disease without boundaries

Cancer occurs when cells are triggered to grow abnormally. Those triggers could include genetics, radiation, and carcinogens — and they go off with alarming frequency.

If current figures hold, approximately one in four Canadians can expect to die of cancer, according to the Canadian Cancer Society. If you're a man, your odds are a little worse: 29 per cent of Canadian men will one day succumb to cancer. For women, the figure is 24 per cent.

Most people who are diagnosed with cancer will eventually die from it. About 40 per cent of Canadian women and 45 per cent of Canadian men will one day be told by their doctors that they have some form of cancer.

Lung cancer continues to claim more lives than any other cancer, accounting for more than one-quarter (27 per cent) of all cancer deaths in Canada. Colorectal, breast and prostate cancers are the next most lethal forms of the disease, with colorectal cancer accounting for almost 12 per cent of cancer deaths. Together, these four types of cancers account for 54 per cent of all cancers diagnosed in Canada.

Among men, prostate cancer is the most common form of the disease but lung cancer the most lethal; among women, the disease is also most lethal in the lungs but occurs most often in the breasts.

In 2011, an estimated 177,800 Canadians will be diagnosed with cancer, and 75,000 will die from the disease. (Statistics exclude non-melanoma skin cancers, which although the most common types of cancer diagnosed in Canada account for very few deaths and are not usually part of cancer registries.)

There were about 4,000 more new cases of cancer in 2011 than in 2010 and 1,200 fewer deaths. The Cancer Society attributes the growth in new cases to population growth and an aging population.

The good news is that we're getting a lot better at detecting, fighting and beating most cancers. Since 1989, mortality rates have been dropping for all age groups among men up to age 79 and for women up to age 69. Overall mortality rates declined by at least two per cent per year for lung, oral, prostate and larynx cancers in males; breast and cervical cancer in females; and stomach cancer and non-Hodgkin lymphoma in both sexes.

Cancer mortality rates are falling the most among children and adolescents.

Source: Canadian Cancer Statistics 2011, Public Health Agency of Canada

*Column totals might not add up to row totals because of rounding.

About 1,300 Canadian children are diagnosed with cancer each year, but thanks to advances in the treatment of the most common cancers, the number of deaths is less than one-fifth the number of cases.

On the whole, Canadians are living longer — and the longer they live, the greater their chance of contracting some form of cancer. About 42 per cent of new cancer cases and 59 per cent of cancer deaths occur in those 70 and older.

By some estimates, at least 50 per cent of cancers can be prevented through healthy living and policies that protect the public. Yet, according to the International Union Against Cancer, about 7.6 million people die of cancer every year around the world and 12 million are diagnosed with the disease. That number is expected to grow by 50 per cent by 2020.

The Canadian Cancer Society  touts seven things individuals can do to protect their health and help ward off preventable cancers:

• Don't smoke.
• Eat your veggies.
• Exercise.
• Stay out of the sun.
• Get screened regularly.
• Visit your doctor and dentist regularly.
• Avoid cancer-causing substances.

Still, you could do everything to reduce your risk of contracting cancer but still develop the disease. You don't have to be a smoker to be diagnosed with lung cancer, for example, although the vast majority of lung cancer cases are linked to smoking.

There are certain cancers you can get from a virus — human papilloma virus (HPV) is responsible for most cases of cervical cancer. It is spread through sexual contact and is said to infect half of all sexually active women between the ages of 18 and 22 in North America.

In most women, the virus clears up on its own, but if the infection persists, it can lead to cervical cancer. Health Canada has approved a vaccine for the virus that would protect females between the ages of nine and 26. In its March 2007 budget, the federal government allocated $300 million over three years for a national vaccination program administered by the provinces and territories. Many school boards across the country have made the vaccine available to girls starting in the seventh grade.

Researchers have also established a strong link between the hepatitis B virus and liver cancer. It's believed that 10 to 20 per cent of people infected with hepatitis B will develop liver cancer. It is a major problem in the developing world, especially parts of Asia and Africa, but in countries where hepatitis B has been a problem and where newborns are routinely vaccinated against the virus, the risk of infection has fallen — as have liver cancer rates.

Despite these advances, the Canadian Cancer Society estimates that by 2020, 14 million people around the world will be dying of cancer every year.