It is projected that about 100-million people will die from cancer within the next decade. Longevity and urbanisation are two factors that play leading roles in the upsurge of cancer in the developed world.
Is cancer on the increase in South Africa?
No one knows what the current prevalence (the number of cancer cases) and incidence (the rate at which new cancer cases are growing) are in South Africa, because the country’s cancer registry has not been updated since 1999. The cancer registry collapsed in the early 2000s when some doctors and pathologists feared they could legally be held liable for disclosing patients’ personal details.
In April 2011, new regulations on the registration of cancer were promulgated, making it compulsory for every healthcare worker who has diagnosed a new case to note it on the prescribed form. However, enough reliable statistics have not yet been gathered. It is estimated that one in four males and one in six females in South Africa will develop cancer at some stage. This information is based on data that was entered into the cancer registry before it collapsed; actual statistics could be significantly higher or lower.
Ageing is considered to be the single biggest contributor to cancer figures rising worldwide. Cancer cells take time to develop and the longer you live the higher the chances are of you getting cancer. In South Africa HIV has had a significant effect on lowering life expectancy.
Antiretroviral drugs (ARVs), which were introduced into the public healthcare system in 2004, are slowly reversing this process: last year, Statistics South Africa said the average life expectancy had risen to 57.1 years from 55.1 years in 2001, and this can at least partly be attributed to ARVs. The number of South Africans on HIV treatment is expected to double by 2016, from the current 1.8-million to 3.6-million. As life expectancy increases, so too will cancer figures.
What are the main causes of cancer in South Africa?
1. Smoking. Worldwide, the most common cause of cancer is smoking. About one out of every three cancer cases is owed to smoking. South Africa has progressive anti-tobacco legislation, but one of the areas activists say can improve is the regulation of smoking at home. Many advocates believe it should legally be possible to ban smoking at home, particularly in cases where domestic workers are employed. Cleaners and domestic helpers should have the right to smoke-free working environments, they say.
Smoking at home is also extremely harmful to children. In the city of Belmont, California, smoking inside flats and townhouses has been declared illegal to protect neighbours.
2. Viruses – such as hepatitis B, which causes liver cancer, and HPV, which leads to cervical cancer – cause about 20% of cancers.
Cervical cancer claims the lives of more than 3400 South African women a year. Black women are more than twice as likely as white women to develop cervical cancer. Unequal access to preventive services such as annual pap smears plays a significant part in this. An HPV vaccine, of which three shots are needed, is available in the private sector. It significantly reduces the risk of women getting cervical cancer.
In 1996 the government was the first in Africa to fund the vaccination of every child for hepatitis B and this is likely to lead to the eradication of liver cancer within the next 20 years in the country.
3. Chemicals are responsible for about 15% of cancer cases. Man-made chemicals such Bisphenol A (BPA), which is used to make certain types of plastic, are strongly linked to breast cancer. Last year, the government banned the use of BPA in baby bottles. Certain types of cling wrap also contain plasticisers that can cause cancer.
Water, particularly in Tlokwe municipality (Potchefstroom), has been found to contain radioactive elements such as uranium. Excessive exposure to uranium is associated with certain types of cancer, including leukaemia.
4. Obesity. Being excessively overweight is strongly associated with the development of cancer. About 15% of cancer cases are linked to it. Obesity often leads to so-called systemic inflammation, when white blood cells invade fat tissue, which is the body’s way of reacting to too many fat cells. Systemic inflammation is one of the preconditions for the development of cancer; it is basically a breeding ground for it.
5. Alcohol. About 3% of European cancer cases in women are associated with alcohol compared with 10% in men in countries such as Germany. Drinking moderately – one to two alcohol units a day – is fine. More than that brings trouble. Binge drinking is more dangerous because the sudden spikes of alcohol in your body often cause more damage than constant exposure.
6. Sunlight. Skin cancers are generally considered trivial, except when melanomas, which are characterised by darker skin pigment, are involved. Melanoma causes about 5% of cancer cases. Too much sun exposure causes normal skin cells to become abnormal. These abnormal cells quickly grow out of control and attack the tissue around them.
The Cancer Association of South Africa commissioned a study, which revealed that most locally manufactured sun-block creams or oils contain amounts of ultraviolet-A filter too low for adequate protection against the sun.
The sun protection factor on sun block is an indication of ultraviolet-B protection. The chemicals needed for ultraviolet-A protection are significantly more costly and therefore often not included in high quantities.
7. Genes. About 10% of cancer cases are linked to what is already in your DNA.
Is there a link between stress and cancer?
Athough many of us seem to believe stress contributes to the development of cancer, scientists have not established a definite link.
Some psychologists are of the opinion that unresolved conflict, which leads to stress, is like a malignant cancer that eventually causes physical harm to the body. The only biomedical link that so far can tie stress to cancer is the development of inflammation. Studies have linked the release of higher amounts of cytokines – molecules that are associated with inflammation – with personal conflict situations.
Both human and animal studies have shown that the body’s response to psychosocial stress leads to inflammation because stress stimulates immune responses that result in the activation of the hypothalamic-pituitary-adrenal axis, sympathetic nervous system and the subsequent regulation of inflammatory responses by immune cells.
How does that link to cancer? Chronic inflammation from infection or conditions such as chronic inflammatory bowel disease is associated with up to 25% of all cancers.
Cancer amounts to cells that multiply too fast and can only happen if something changes the DNA of cells in your body. For this to happen, inflammation first has to take place.
If stress therefore increases the inflammation in your body, it is theoretically possible that it can also add to your risk of developing cancer. But more research is needed to establish definite links.
If such connections are established, it could have implications for the role of psychotherapy in cancer prevention; that is, if unresolved conflicts are addressed through counselling sessions, it could lead to fewer cases of cancer.
Mia Malan works for the Discovery Health Journalism Centre at Rhodes University
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