Cancer: not an African problem?

Adrienne Edkins

Very few people’s lives have not been touched by this disease. Whether it is a personal experience or through a loved one, cancer is an unfortunate fact of daily life for most people.

Biologically speaking, cancer is the term used to describe the collection of diseases that arise due to the uncontrolled growth and spread of cells in the body. These abnormal cells escape the biological restrictions that keep the growth of most normal cells under control. In cancers, cells become malignant, growing continuously, competing with other cells for nutrients and space and, in the worst cases, spreading to other parts of the body. The majority of deaths from cancer are due to secondary tumours or “metastases” and not the primary tumour.

Cancers develop for a wide range of reasons. Certain cancers, such as cervical cancer and Karposi’s sarcoma are caused by viral infections, while many other cancers are caused by mutations that occur in the DNA of cells. Many mutations are caused by preventable environmental factors, the best examples of which include chemicals in cigarette smoke or UV radiation from the sun. These so called ‘carcinogens’ induce chemical changes to the structure of the DNA of the cell that in turn changes the behaviour of that cell. If the mutation causes the activation or increased production of an oncogene, then this could lead to cancer. Alternatively, the mutation may result in the loss of a gene known as a tumour suppressor.

As tumour suppressors are normally associated with anti-cancer activities, a change in the function of a tumour suppressor may prevent its normal anti-cancer activities. Some heredity genetic mutations may also make you more susceptible to developing cancer. Heredity mutations can become over-represented when new populations develop from a small number of individuals. An example of this so-called ‘founder effect’ is the increased risk of BRCA positive heredity breast and ovarian cancers in members of the Ashkenazi Jewish population.

Unless treated by surgery, radiation or chemotherapy, cancer is often fatal.  Deaths from cancer worldwide outnumber the combined deaths from HIV/AIDS, tuberculosis and malaria. Yet one of the most predominant misperceptions about the disease is that cancer is not really an African problem. Africans, it sometimes appears, get malaria and tuberculosis, but not cancer. It is not to say that research into tropical diseases is not necessary and important, but when was the last time you saw a charity campaigning for donations, or calling for applications to support cancer research and treatment in Africa? In fact, non-communicable diseases, and cancer in particular, contribute to more deaths in the developing world than the diseases of poverty more commonly associated with Africa.

The risk of dying from a range of cancers in many African countries (including South Africa) is greater than that in the USA or UK. Over half of the approximately 8 million deaths from cancer in 2008 occurred in populations in the developing world and this is expected to increase to over two thirds in the next 20 years. Certain cancers appear to disproportionately affect Africa populations. In some cases, this is due to an underlying infectious causative agent, such as Karposi’s sarcoma. Karposi’s sarcoma in Africa is predominantly an AIDS-related cancer caused by a virus called human herpes virus 8 (HHV8) and develops in the background of the immunocompromised individual.

But it is not only cancers caused by oncoviruses that affect the Africa community. It is estimated that more than half of breast cancer deaths occur in women who live in developing countries. Data from American studies suggest that while white women are more likely to develop breast cancer, black women are more likely to develop a highly aggressive form of this disease, known as triple-negative breast cancer. This type of breast cancer is often resistant to treatment and affects younger women. Only a third of sufferers of triple negative breast cancer will survive longer than 5 years even with therapy.

Southern African women are at the greatest risk of all African women for developing breast cancer, although the incidence of breast cancer in Ugandan and Algerian women has almost doubled in the past twenty years. Breast cancer in men is relatively rare in American populations (approximately 1%) but in certain parts of Africa, men appear more prone to the disease. In Zambia, 15% of breast cancers occur in men, while breast cancer rates in Egyptian men are over ten times that in American men.

The sad reality is that most of these statistics from South Africa and other African countries are likely to be under-representations of the true numbers. This is particularly true of communities that still lack access to proper health care.

For many people in developed countries, cancer is no longer a death sentence. There have been some breakthroughs in developments of certain cancer treatments. The drug Herceptin, for example, revolutionised the treatment of a large subset of breast cancers that were associated with a specific protein called Her2. However, a far greater contribution to cancer survival rates in developed countries is made as a result of prevention strategies, rather than treatments. Routine screening programs, early diagnosis and education have all contributed to a drop in mortality rates.

Advances in survival rates in many developed countries are not mirrored in developing countries such as those in Africa which often lack standardised prevention strategies. The WHO recently published a shocking report showing that over half of the countries in the world lack the necessary infrastructure and dedicated funding to prevent, detect and treat cancer.

Unfortunately, this applies to most African countries, although South Africa is relatively better off than some of its African cousins. We have a growing National Cancer Registry and public health facilities that are working to improve education and treatment of cancers. This is complemented by the work of the Cancer Association of South Africa (CANSA) which has done much to improve education and awareness of cancer, both independently and through its collaborations with agencies such as the Medical Research Council. The drive to promote vaccination to prevent cervical cancer is an excellent example of a positive and forward-thinking approach to first line cancer prevention.

However, one aspect that the recent WHO report does not address is the need for targeted funding for cancer research in Africa. We need cancer research that is tailored to the South African environment; research that investigates the specific causes and developmental mechanisms of those cancers that are prevalent in our society and specific to our environmental and genetic risk factors. South Africa, in particular, has many talented researchers working in this field. Yet, funding for this research is inadequate.

Despite the best efforts by national funding bodies, the levels of funding specifically dedicated for cancer research is not sufficient to support progress. International funding for cancer research in Africa is practically non-existent. The impact of international funding from agencies such as the Wellcome Trust or the Gates Foundation on tropical disease research cannot be underestimated. But most international organisations do not fund African scientists to complete fundamental or applied research on cancer cell biology. The reason for this cannot be that South Africa does not have the capacity to do this research, but rather that cancer research is not perceived as a priority for Africa.

There are numerous South African academics with expertise and ideas who are doing cutting edge research as best they can on limited and transient funding. In addition, our country has a great resource in the form of our indigenous natural environment that yields a number of local species with anti-cancer activity that could be developed into the next generation of chemotherapeutic agents. We need to foster cancer research that is relevant and translational.

Researchers often work isolated from the clinical interface, while many clinicians are not aware of the latest research developments in personalised treatments for cancer. Yet, despite significant worldwide investment in cancer research and recent clinical success in early cancer detection and treatment, the “cure” for cancer remains elusive. It is painfully obvious that some of the brightest minds have spent their whole lives working to understand this disease and there still remain significant challenges. Some might think that the proposal that South African laboratories could make a difference is arrogant or misguided. True, we might only make a small contribution to the worldwide battle against this disease, but surely the far-reaching impact of this disease means that the world needs all the help it can get? To suggest that African research should focus only on tropical diseases is to fail the many people with cancer in South Africa.

 

Explanation of some key terms

Carcinogen:  A substance that can cause cancer
DNA Deoxyribonucleic acid: the molecule that is housed in cells and carries the genetic information of that organism
Founder effect: Loss of genetic variation in a population as a result of that population arising from a small founding population that represents a subset of a larger population
Malignant: Having cancerous and invasive properties
Metastasis: The spread of cancer from the point of origin to other sites in the body
Oncogene: A gene with the potential to cause cancer when it is activated or present at high levels
Oncovirus:  A virus that has the potential to cause cancer
Tumour suppressor: A gene with anti-cancer activity that results in cancer when its function is prevented