Besides advocating strategies for preventing cancer (primary prevention), many health professionals encourage early detection of cancer through a screening programme (secondary prevention). The basic understanding of screening for cancer, using a particular test, is that early (prior to symptoms or signs being present) detection of the disease suggests that the cancer is at an early stage and that initiating treatment promptly will lead to better health outcomes and prolonging life. Although this reasoning is instinctive and is broadly accepted by health professionals and the general public, its validity is unclear for many cancers.(1)
There is substantial evidence that screening programmes for breast, cervical, colorectal, and, recently also, lung cancer have led to a decrease in cause-specific mortality.(2) For it to be effective, any cancer screening must take into consideration several factors, including the burden of suffering, the frequency of cancer, and the severity of its health effects. In addition, it is important to analyse the accuracy and reliability of the screening test in detecting cancer and minimizing inaccurate test results. The screening protocol must also assess the effectiveness of early detection and its incremental benefit of detecting and treating cancer at an earlier stage. Two other critical elements are the unintended harms of screening and, in developing countries, what often becomes a limiting factor is the cost of the screening program. The aforementioned factors form the basis of decisions to weigh the benefits and harms of screening.
The general principle is that if a screening test improves health and reduces mortality, it should be offered to the whole population. Unfortunately, this principle is not applicable in many developing countries as there is a social gradient regarding health and health care in these countries. Although regarded as a middle-income country, South Africa has a huge socioeconomic divide, and many people suffer from this socioeconomic gradient in health and healthcare. Thus, those with poor financial means also have poorer health and do not get all the necessary health care. This link, unfortunately, also exists for the access and provision of preventive health care. Some studies have shown that people with limited means also take less part in cancer screening, which could lead to later cancer diagnosis, leading to a higher mortality rate. Studies have also shown that those on the lower socio-economic spectrum also adhere less to follow-up colonoscopy after a positive faecal immunochemical test in colorectal cancer screening.(3) Thus, cancer screening programs for cancer must try and fit them to local conditions based on available access and cost.
This journal issue highlights a few aspects of cancer in South Africa. First, Basson D and colleagues highlight the prevalence of brain cancer in the Western Cape Province of South Africa, and to understand the epidemiology of this form of cancer, the authors plead for the creation of a national registry for brain cancer in South Africa. This journal issue also highlights the current status of two important screening programmes: colorectal cancer and PSA screening for prostate cancer. Both papers discuss the current international guidelines for screening these common cancers but, importantly, frame their discussion on using these screening protocols appropriately based on the South African epidemiology of these cancers.
Pravin Manga
Editor
Wits Journal Clinical Medicine