South Africans were shocked when popular Radio 702 host Xolani Gwala confirmed on air that he was suffering from advanced colon cancer.
“It’s going to be a very difficult fight, and a long fight, but [it’s] a fight that I’m ready for,” Gwala told Stephen Grootes, his stand-in on the station’s breakfast slot.
Gwala said he intends to raise awareness about cancer, given that the disease occurs “all over”.
“We just need to deal with a lot of myths about cancer. And there are so many of them. One of them is that it is a white people’s disease.”
What is cancer?
Cancer can be defined as an abnormal and uncontrolled growth of body cells that could affect almost any part of the body. These abnormal cells grow beyond their usual boundaries, often invading adjoining parts of the body, and can spread to other organs.
Approximately 14 million new cases of cancer were diagnosed worldwide in 2012, according to the World Health Organization. Cancer-causing infections, such as hepatitis and the human papillomavirus (HPV), are responsible for up to 25% of cancer cases in low- and middle-income countries.
Around a third of cancer deaths are due to five leading behavioural and dietary risks:
- high body mass index,
- low fruit and vegetable intake,
- lack of physical activity,
- tobacco use, and
- alcohol use.
What are the main cancers affecting South Africans?
South Africa’s main cancer statistics source is the National Cancer Registry, which was established in 1986. It collates and analyses cancer cases diagnosed in pathology laboratories nationwide.
In 2011, the National Health Act formally established the National Cancer Registry as South Africa’s main cancer surveillance agency. Since then, the legislation makes it mandatory to report all confirmed cancer diagnoses to the registry.
The registry releases cancer statistics in an annual report and the latest one is for 2013.
Cancer cases reported by the registry are diagnosed histologically. This means that a sample of tissue (a biopsy) is taken from the tumour and sent to a laboratory for examination under a microscope. Only then can the cancer be diagnosed with certainty.
However, in some cases, a histological diagnosis is not possible. These include when the patient is seen by the doctor or nurse at an advanced stage of the disease, or a biopsy is not feasible, or there is no access to a pathology laboratory.
In such cases, health professionals often rely on a clinical diagnosis. This means that the cancer is diagnosed based on patient-reported symptoms and on medical signs, rather than laboratory tests.
These cases are not reported by the National Cancer Registry and the results presented next are therefore an underestimation of the true occurrence of cancer in South Africa.
Diagnosed cancer cases
The National Cancer Registry releases statistics classified according to South Africa’s four main population groups: black, white, coloured and Indian/Asian.
Breast cancer was the most common cancer for women of all races in 2013, except for black women, who were most likely to be diagnosed with cervical cancer. Among black women, Kaposi sarcoma – a blood vessel cancer which is associated with HIV infection and presents as growths in the skin and other organs – and food pipe (oesophagus) cancer were the fourth and fifth leading cancer, but did not appear in the top five of other races.
Lung cancer, which featured in the top five for coloured, white and Indian/Asian women, wasn’t prominent among black women. Melanoma (cancer of the skin) was common among white women, but did not appear in the top five of other races.
(Note: Non-melanoma skin cancers – basal and squamous cell carcinomas – are excluded from these rankings as they spread regionally rather than to distant sites, the head of the South African National Cancer Registry, Dr Elvira Singh, told Africa Check.)
For men of all races, prostate cancer was the most common lab-diagnosed cancer.
Kaposi sarcoma and oesophagus cancer took the second and fourth spot for black men, but did not appear in the top five of other races. Melanoma (cancer of the skin) was common among white men, but did not feature in the top five of other races.
At first glance, a trend analysis of the National Cancer Registry’s data from 2004 to 2013 confirms the impression that cancer is a white person’s disease.
Except for 2007 to 2010, white people had the highest share of histologically diagnosed cancers. In 2013, the group – which made up 8.7% of the South African population then – accounted for half of lab-diagnosed cancers.
However, experts caution this may have more to do with better access to healthcare than reflecting actual cancer cases.
(Note: Between 2004 and 2010, some private laboratories withheld data from the registry because of concerns about voluntarily submitting confidential patient information without the protection of government legislation. It only resulted in an estimated overall decrease of less than 4% in reporting, however.)
In 2012, cancer was South Africa’s fifth leading cause of death, causing 8.7% of all deaths, according to the South African Medical Research Council.
The data originates from death notifications obtained by Statistics South Africa. In 2012, 43,888 deaths due to cancer (“malignant neoplasms”) were registered.
Most cancer deaths (60%) were among black people, but the disease still seemed to disproportionately affect white people.
|Cancer deaths per population group (2012)|
Source: Medical Research Council
What lies behind the difference in cases & deaths?
First things first: Everybody is susceptible to develop cancer irrespective of age, sex or race, Ntuthu Somdyala, senior scientist at the South African Medical Research Council, told Africa Check.
Cancer is a multifactorial disease, explained Dr Elvira Singh, head of the South African National Cancer Registry. “There is rarely one seminal event which results in the development of cancer. Rather, there is a series of damaging events, including genetic mutations, environmental risks, lifestyle factors and infectious agents which may influence the risk for cancer.”
How these factors typically play out in South Africa’s different population groups can help explain the difference in cancer cases and deaths recorded.
Access to healthcare
“In South Africa, race is often a proxy for socioeconomic status and particularly access to healthcare,” Singh said. “It has been reported that white and Asian populations more commonly access private healthcare in South Africa, where diagnostic, and particularly screening facilities may be more readily available.”
Cases in these subgroups are therefore more likely to be registered compared to cancer cases in public healthcare facilities.
“A propensity towards a Westernised lifestyle with the attendant risk factors such as obesity, fatty and low-fibre diet and lack of physical activity, as well as smoking and alcohol use, may predispose the more affluent populations, such as the white population, to cancer.”
As South Africa and the continent transform socially and economically, Singh expects the difference in risk to change too.
Cultural differences between population groups play a role as well. Traditionally, black women have low smoking rates, which could explain the low incidence of lung cancer in this subgroup.
Somdyala noted that health-seeking behaviour is often poor among African populations, especially men, and as a result, many cancers go undiagnosed.
Differences in sexual practices and reproductive health may also affect the incidence of cancer by population group, Singh said.
“The prevalence of sexually transmitted infections such as HPV and HIV in a community may directly influence the rates of cancers.”
The risk of cancer increases with age, Somdyala explained. “The older one grows the higher the chances are of developing cancer. This is because of cell changes, which can grow into a tumour, but which a young body is usually able to repair.”
South Africa’s 2016 Community Survey showed that white people’s median age – the age at which half the group is younger and the other half older – is 40 years. This was the highest of all the main population groups.
|Median age of SA population groups|
Patrick Ngassa Piotie (@PatNgassa) is a medical doctor hailing from Cameroon and has a master’s degree in public health from the University of Pretoria.
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