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Cancer statistics in SA skewed by incomplete data, under-reporting

The World Health Organisation said in February that about 1.1m new cancer cases are being reported in Africa annually, with about 700 000 deaths, and while a recent report provides important new data on cancer in South Africa, the picture remains incomplete, writes Ufrieda Ho in Spotlight.

Statistics South Africa’s report on cancer in South Africa (2008-19) released at the end of March is intended to inform cancer treatment and a cancer management strategy for the country, which is especially necessary since the National Strategic Framework for Cancer lapsed in 2022.

However, there are questions about how accurately cancer cases and deaths are being recorded. The resulting gaps in data and data management raise concerns about a skewed picture of the actual disease burden. The unknowns are potential knock-on effects for resource allocation and infrastructure planning.

The WHO estimates that by 2030, deaths from cancer in Africa will edge up to 1m a year, that 70% of cancer deaths worldwide occur in low- and middle-income countries, “where resources for prevention, diagnosis and treatment are limited or non-existent”.

The Stats SA report is based on information from the National Cancer Registry and Stats SA’s mortality and death notification data. It provides a breakdown of the incidence and deaths from different cancers across the population based on age, race, gender and province of residence over the reporting period.

The findings show that these deaths increased by 29.3% from 2008 to 2018, even as overall mortality in SA dropped by 24.1% in that same period. In 2019, just more than 85 000 South Africans were diagnosed with cancer, and in 2018 there were just under 44 000 registered deaths from the disease.

Key findings

According to the report, in 2018, cancer accounted for 9.7% of all deaths recorded in the country, making it the fourth leading cause of mortality after circulatory diseases (stroke, hypertension and heart disease) at 18.5%, infectious and parasitic diseases (eg TB and HIV) at 16.4%, with external causes of mortality (accidents, assault and firearm-related deaths) at 12%.

In 2018, women accounted for 51.3% of cancers diagnosed while men accounted for 48.6%. The median diagnosis age was 59 for females and 64 for males and the median age at death was 62 for females and 64 for males.

“This suggests cancer in males may be diagnosed at more advanced stages than in females, thus the shorter survival period,” the report found.

The most commonly diagnosed cancers among males were prostate, colorectal and lung: bronchus and lung cancer accounted for 18.7% of cancer-related deaths, prostate cancer contributed 16.7%, oesophagus 7.5%, colorectal 6.8% and liver and intrahepatic bile ducts 5.2%.

Among women, the most diagnosed cancers were breast, then cervical and colorectal cancer. Between 2008 and 2018, deaths from cervical cancer increased by 50.5% (from 2 653 in 2008 to 3 994 in 2018). Breast cancer deaths increased by 42.4% (from 2 665 to 3 796), while those from bronchus and lung cancer rose by 38.2% (from 1 491 to 2 060) and colorectal by 45.1% (from 945 to 1 371).

Incomplete data

Salomé Meyer of the Cancer Alliance – a civil society collective of cancer support organisations and advocates – says the key concern about the report is what it doesn’t factor in: gross under-reporting of cancer incidence/deaths in South Africa, which in some instances is believed to be as high as 40%. She says without proper mechanisms and standardised population-wide data gathering, even this number remains unverifiable.

“There are multiple reasons for the discrepancies. The private sector does not necessarily provide details of their cases. And not all cancers are diagnosed through pathology testing – and the National Cancer Registry is pathology-based.”

Additionally, deaths are registered according to a secondary cause of death. For instance, if someone is diagnosed with cancer but their organs fail and they die, death is recorded as being from organ failure, not cancer. Meyer says a further complication arises when there is no medically trained person to do death reporting.

“Traditional leaders are allowed to do death reporting and provide a death certificate, but if they are not trained to diagnose that someone died of cancer, they will not record it as such.”

A population-based cancer registry as well as survival data are needed, she adds.

These two additional streams would provide a clearer picture and also answer important questions about how well South Africa manages cancer patients and where there needs to be more targeted intervention.

“We need to understand why there is under-reporting and also how some people are living longer after their diagnosis and where, and how inequities are contributing to others getting treatment later and dying sooner.”

‘Massive challenge of under-reporting’

Dr Mazvita Muchengeti, HoD for the National Cancer Registry at the National Health Laboratory Services, which is part of the National Institute for Communicable Diseases (NICD), acknowledges that for some cancers, there is under-reporting.

“For well-biopsied cancers like breast cancer, the stats are comparable to hospital registries, but for cancers primarily diagnosed radiologically or clinically – like liver and lung cancers – under-reporting is very high,” she says.

From 2011, the National Health Act made cancer a reportable disease, which has led to an improvement.

“But an increase in the number of reported cancers does not necessarily translate to an increase in cancer, we are just counting cancer cases better because it is now compulsory.” To what extent increased reporting is driving the rising cancer numbers reported by Stats SA is not clear.

Muchengeti also confirms that the National Cancer Registry, established in 1986, does not hold data on the full count of cancers.

“It is pathology-based, meaning data of cancers confirmed by laboratory means. So, those diagnosed by other means – like clinically or radiologically diagnosed cancers – are not counted.”

The NICD is in the process of establishing population-based cancer registries to be launched at “sentinel sites”, as yet un-named.

“There are limited funds and human resources for the establishment of population-based cancer registration (which counts all cancers), but there is need for cooperation and harmonisation of all data sources, both public and private (from laboratories, medical aid societies, managed care organisations and death registry data), to get a full picture of cancer in the country.”

 

Cancer in SA

Spotlight article – New report paints grim, but incomplete picture of cancer in SA (Creative Commons Licence)

 

See more from MedicalBrief archives:

 

Cancer deaths in South Africa on the rise

 

Rise in young South Africans afflicted with and dying of cancer

 

Ageing population contributes to high cancer deaths in SA

 

SA cancer rates set to double by 2030, actuaries predict

 

 

 

 

 

 

 

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