Cancer: An Overview
- Global Oncology and Country Statistics
- Country Data/Statistics
- What is Cancer?
- How Do Tumors Form?
- What Causes Cancer?
- When to Seek Help
- How is Cancer Treated?
- Cancer: One Disease, Many Faces
- Cancer Staging
Cancer Care in the Past, Now and in the Future
Cancer: An OverviewGlobal Oncology and Country Statistics
More than 12 million cases of cancer are diagnosed worldwide every year. Cancer is a leading cause of death globally, causing approximately 7.6 million-or 13 percent-of all deaths worldwide. Only cardiovascular diseases, which account for 23.6 percent of deaths globally, are responsible for more deaths.
The five most prevalent cancers are:
- breast cancer: (age-standardized incidence [ASR]: 38.9 per 100,000)
- prostate cancer: (27.9 per 100,000)
- lung cancer: (22.9 per 100,000)
- colorectal cancer: (17.2 per 100,000)
- cervical cancer: (15.2 per 100,000)
The cancers that are responsible for the most deaths worldwide annually include (data from 2008):
- Lung cancer (1.37 million deaths)
- Stomach cancer (736,000 deaths)
- Liver cancer (695,000 deaths)
- Colorectal cancer (608,000 deaths)
- Breast cancer (458,000 deaths)
- Cervical cancer (275,000 deaths)
Tthe highest rates of cancer are found in Denmark (326.1 per 100,000), Ireland (317 for 100,000), Australia (314.1 per 100,000), New Zealand (309.2 per 100,000), and Belgium (306.8 per 100,000). Lifestyle factors are thought to contribute to these high cancer rates, but improved diagnostic techniques are also considered a factor. Click ere for a full listing of global cancer prevalence rates.
Despite common assumptions that cancer is more prevalent in the developed world, 56 percent of all cancers (excluding non-melanoma skin cancer) are diagnosed in less developed countries. This percentage is expected to rise to more than 60 percent by 2030, due to life expectancy and population growth in these regions.
The total economic impact of premature death and disability from cancer worldwide is $895 billion USD, which represents 1.5 percent of the world's gross domestic product (GDP). This translates to a total of 83 million years of "healthy life" lost due to death and disability from cancer annually.
Although cancer research is leading to an increased understanding of the causes of and risk factors for the disease, an aging global population and lifestyle changes have led the World Health Organization (WHO) to predict that the number of cancer cases will increase to 15 million by 2020. Despite ongoing advances, the total number of cancer deaths is projected to increase to 13.1 million by 2030.
In most western countries, including France, Germany, Italy, the UK and U.S., the four most prevalent cancers mirror global patterns and include breast, prostate, colorectal and lung cancers. In Japan, however, the most prevalent cancer is breast cancer, followed by stomach, colorectal and lung cancer. In all six of these countries, lung cancer is responsible for the most cancer-related deaths.Cancer is a general term used to describe many diseases where abnormal cells divide uncontrollably, form a mass called a tumor, invade body tissues and use the blood and lymph system as a "motorway" to spread to other parts of the body. The lymph system is a network of organs, nodes, ducts and vessels that transport lymph-an immune system fluid made primarily of white blood cells that attack bacteria in the blood-from tissues to the bloodstream.
In the body, normal cells grow and divide throughout a person's life. When cells get old or damaged, they die and are replaced with new, healthy cells. Unfortunately, this system sometimes malfunctions. Genetics, carcinogens or viruses produce DNA damage (also known as mutations) in genes that are responsible for the cells' growth and division.
When these mutations happen, cell growth and division can occur uncontrollably, leading to the formation of tumors. Tumors can be benign or malignant. Benign tumors are non-cancerous growths; they grow in one place and do not spread or invade other parts of the body. Malignant tumors are cancerous growths, and cells from these tumors can invade nearby tissues. They can also break away and metastasize, or spread, to other parts of the body. Some types of cancer (such as leukemia, or blood and bone marrow cancer) do not form tumors but simply spread through the body's fluids.
Most cancers are named for the organ or type of cell where they start growing in the body-e.g., lung cancer or basal cell carcinoma (skin cancer that starts in the basal cells). The World Health Organization says cancer is a generic term and may also be referred to as "malignant tumors" or "neoplasms" (cancerous, abnormal tissue growths).
Tobacco use causes 22 percent of all cancer deaths and 71 percent of lung cancer deaths, making it the most important risk factor for cancer. Along with tobacco use, almost a third of cancer deaths worldwide (30 percent) are due to other preventable factors, such as:
- Poor nutrition, particularly eating low amounts of fruits and vegetables
- Not exercising
- Excessive alcohol consumption
- Occupational and environmental hazards (e.g., pollution, exposure to asbestos and other carcinogenic [cancer-causing] chemicals)
- Too much exposure to sunlight and UV rays
In low- and middle-income countries, up to 20 percent of cancer deaths are caused by viral infections, such as hepatitis B, hepatitis C and the human papillomavirus (HPV). In particular, cervical cancer caused by HPV is a leading cause of death among women in low-income countries. Genetics and family history also play a role in cancer risk and development.
As with many illnesses, cancer deaths can be reduced if the disease is caught and treated in its early stages. Screenings-and therefore earlier diagnosis-particularly in areas with limited resources, are important, as most patients in these regions discover they have cancer only after the disease is in late stages when treatment is less effective.
Depending on the type and stage of cancer, treatment may include surgery, radiation and/or treatment with medicines, including chemotherapy. Though cancer treatment is physically and emotionally challenging, the goal is three-fold:
- To rid the patient of cancer
- To prolong the patient's life
- To improve the patient's quality of life
Cancer can originate in any part of the body and in any type of cell, and there are more than 200 different types of cancer.
Cancer types are often categorized for easier identification. The five main cancer categories are:
- Carcinoma: cancer of the skin or tissues that line internal organs
- Sarcoma: cancer of the bone, cartilage, fat, muscle, blood vessels or other connective tissue
- Leukemia: cancer of the blood or bone marrow
- Lymphoma and myeloma: cancer of the immune system
- Central nervous system cancers: cancer of the brain or spinal cord
When a patient is diagnosed with cancer, tests are performed to determine the cancer's severity. This is known as staging, and is an important marker that helps the oncologist plan appropriate treatment and estimate the patient's prognosis.
Physical exams, lab tests, imaging procedures, and/or pathology and surgical reports are used to determine a tumor's stage. Most tumors are described using the TNM staging system is based on the extent of the tumor (T), and whether or not cancer cells have spread to the lymph nodes (N) or metastasized to other parts of the body (M). This information is used to give an overall stage to the patient and is often translated into the more familiar Stage 0 to IV scale:
- Stage 0: Small, cancerous tumor in situ (in its original place)
- Stage I-III: A higher stage means more extensive disease, such as a larger
- tumor size or spread of the cancer to lymph nodes and/or tissues and organs near the original tumor
- Stage IV: The cancer has metastasized to other organs throughout the body
Approximately 5 to 10 percent of all cancers are hereditary. People who have a genetic family history of cancer have a greater chance of developing cancer at some point in their lives.
The mainstays of cancer treatment have traditionally been surgery, radiation and chemotherapy.
Surgery as cancer treatment was used as early as the 1800s and has advanced to become more specific and less invasive. For example, early mastectomies involved the removal of the entire breast, surrounding lymph nodes and chest muscles. Today, many patients are able to avoid mastectomy altogether.
Radiation was the second anti-cancer therapy developed and was first used in 1903. External beam radiation, as well as radioactive seeding (in which small radioactive implants are inserted into the tumor and emit radiation to kill the tumor cells), both play a part in modern cancer therapy.
In 1949, the first chemotherapy agent was approved and cancer treatment has evolved significantly since then. In 1958, the first combination chemotherapy was used to treat leukemia and the use of combination chemotherapies has continued to expand. Chemotherapy is an important part of cancer treatment today and continues to improve continuously. Advances include: reducing side-effect profiles (such as hair loss and anemia), improving treatment success rates and increasing quality of life during treatment.
Surgery, radiation and chemotherapy can also be combined to improve patient response to treatment. For example, adjuvant chemotherapy (chemotherapy given after the tumor has been treated by another method) first appeared in the mid-1970s and involved the use of chemotherapy after surgery in breast cancer patients. Today, many cancers are treated using combinations of chemotherapy and radiation, chemotherapy and surgery, or surgery and radiation.
Modern cancer therapy is becoming more focused on cancer at the genetic and molecular levels. Research advances and the uncoding of the human genome have allowed deeper insight into the molecular mechanisms that cause cancer. As a result, targeted therapies have been developed that treat cancer at the molecular level. They are designed to act against a specific molecule that has been altered or mutated, causing cancer.
One of the first approved targeted therapies developed using molecularly driven drug design was Novartis' imitanib (Gleevec) for chronic myelogenous leukemia (CML). It targets a genetic defect and is only effective in patients who are positive for the mutation.
Targeted therapies have ushered in the era of tailored therapeutics (also known as personalized medicine). By understanding an individual's cancer at a molecular level, therapies can be tailored to each patient to ensure he/she receives treatment that will be most effective for his/her individual cancer. This new treatment paradigm will minimize the "trial and error" treatment approach that had been the mainstay of cancer treatment. A targeted approach to clinical trials is also becoming more common, leading to quicker advancements.
Immunotherapies use components of the immune system or mimic the immune system to target cancer cells. Types of immunotherapies used to treat cancer include monoclonal antibodies (a synthetic molecule that mimics antibodies of the immune system), cancer vaccines and therapies that boost the immune system.
The future of cancer treatment relies on a further understanding of the mechanisms leading to cancer and continuing to understand that cancer is not one disease but many. Classifying cancer by the organ it affects will become less important. Instead, the focus will continue to shift to the genomic and molecular makeup of the tumor, and how it interacts with the body. This approach is aimed at leading to improved tailored therapeutics.