WHO updates its fact sheet on Cancer (2 February 2018)

Ahead of World Cancer Day on 4th February, the World Health Organization (WHO) has updated its fact sheet on cancer. The theme this year is ‘We Can. I can’.

Background Information:

Cancer arises from the transformation of normal cells into tumour cells in a multistage process that generally progresses from a pre-cancerous lesion to a malignant tumour. These changes are the result of the interaction between a person’s genetic factors and three categories of external agents, including:

physical carcinogens, such as ultraviolet and ionizing radiation;
chemical carcinogens, such as asbestos, components of tobacco smoke, aflatoxin (a food contaminant), and arsenic (a drinking water contaminant); and
biological carcinogens, such as infections from certain viruses, bacteria, or parasites.

Ageing is another fundamental factor for the development of cancer. The incidence of cancer rises dramatically with age, most likely due to a build-up of risks for specific cancers that increase with age. The overall risk accumulation is combined with the tendency for cellular repair mechanisms to be less effective as a person grows older.

Key Messages:

Cancer is one of the leading causes of morbidity and mortality worldwide, with approximately 14 million new cases in 2012.

The economic impact of cancer is significant and is increasing. The total annual economic cost of cancer in 2010 was estimated at approximately US$ 1.16 trillion.

Cancer is the second leading cause of death globally, and was responsible for 8.8 million deaths in 2015. Globally, nearly 1 in 6 deaths is due to cancer.

The number of new cases is expected to rise by about 70% over the next 2 decades.

The most common causes of cancer death are cancers of:

Lung (1.69 million deaths)
Liver (788 000 deaths)
Colorectal (774 000 deaths)
Stomach (754 000 deaths)
Breast (571 000 deaths)

Approximately 70% of deaths from cancer occur in low- and middle-income countries.

Around one third of deaths from cancer are due to the 5 leading behavioral and dietary risks:

high body mass index,
low fruit and vegetable intake*,
lack of physical activity*,
tobacco use*, and
alcohol use*.

*These are shared risk factors for other non-communicable diseases as well.

Tobacco use is the most important risk factor for cancer and is responsible for approximately 22% of cancer deaths.

Cancer causing infections, such as hepatitis and human papilloma virus (HPV), are responsible for up to 25% of cancer cases in low- and middle-income countries.

Between 30–50% of cancers can currently be prevented by avoiding risk factors and implementing existing evidence-based prevention strategies.

Modifying or avoiding key risk factors can significantly reduce the burden of cancer. These risk factors include:

tobacco use including cigarettes and smokeless tobacco
being overweight or obese
unhealthy diet with low fruit and vegetable intake
lack of physical activity
alcohol use
sexually transmitted HPV-infection
infection by hepatitis or other carcinogenic infections
ionizing and ultraviolet radiation
urban air pollution
indoor smoke from household use of solid fuels.

To prevent cancer, people may:

increase avoidance of the risk factors listed above;
vaccinate against HPV and hepatitis B virus;
control occupational hazards;
reduce exposure to ultraviolet radiation;
reduce exposure to ionizing radiation (occupational or medical diagnostic imaging).

Vaccination against these HPV and hepatitis B viruses could prevent 1 million cancer cases each year.

Cancer mortality can be reduced if cases are detected and treated early. There are two components of early detection:

Early diagnosis

When identified early, cancer is more likely to respond to effective treatment and can result in a greater probability of surviving, less morbidity, and less expensive treatment. Significant improvements can be made in the lives of cancer patients by detecting cancer early and avoiding delays in care.

Early diagnosis consists of 3 steps that must be integrated and provided in a timely manner:

awareness and accessing care
clinical evaluation, diagnosis and staging
access to treatment.

Early diagnosis is relevant in all settings and the majority of cancers. In absence of early diagnosis, patients are diagnosed at late stages when curative treatment may no longer be an option.

Screening

Screening aims to identify individuals with abnormalities suggestive of a specific cancer or pre-cancer who have not developed any symptoms and refer them promptly for diagnosis and treatment.

In general, a screening programme is a far more complex public health intervention compared to early diagnosis.

Examples of screening methods are:

visual inspection with acetic acid (VIA) for cervical cancer in low-income settings;
HPV testing for cervical cancer;
PAP cytology test for cervical cancer in middle- and high-income settings; and
mammography screening for breast cancer in settings with strong or relatively strong health systems.

Palliative care

Palliative care is treatment to relieve, rather than cure, symptoms caused by cancer and improve the quality of life of patients and their families.

Relief from physical, psychosocial, and spiritual problems can be achieved in over 90% of advanced cancer patients through palliative care.

Improved access to oral morphine is mandatory for the treatment of moderate to severe cancer pain, suffered by over 80% of cancer patients in terminal phase.