Colorectal cancer (CRC) is no longer a disease of the Western world. Although historically CRC rates were far lower in low- and middle-income countries (LMICs) than high-income countries, globalization has changed the game entirely.
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The recent perspective piece by Parker et al3
highlights the increased incidence of CRC in sub-Saharan Africa (ssAfrica), detailing the experience at an East African hospital where CRC incidence rates have increased by over 300% in 2 decades. Their findings are consistent with several independent analyses demonstrating a rising incidence of CRC in ssAfrica.4
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Given the lack of organized CRC screening in most LMICs, these trends are notable and warrant further attention.According to the American Cancer Society and the International Agency for Research on Cancer, CRC is the fifth most common malignancy in ssAfrica.
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In response to provider observation that CRC has become a more frequent diagnosis at Tenwek Hospital in rural Kenya, Parker et al3
calculated the age-standardized rate of pathologically diagnosed CRC cases per 100,000 people per year using the world standard population and Kenyan census data. They found that the age-standardized rate for CRC increased from 2.9 cases per 100,000 people per year (between 1993 and 2012) to 9.6 cases per 100,000 people per year (between 2013 and 2017). In addition, 20% of diagnoses were made in individuals younger than 40 years, compared with 3% to 7% in high-income countries. The authors also note a predominance of left-sided colon and rectal CRC tumors, which are more likely to present with symptoms of hematochezia, pain, and/or obstruction than the right-sided lesions that predominate in the United States. In the absence of universal CRC screening and low use of diagnostic colonoscopy in Kenya, most patients diagnosed were symptomatic and, unfortunately, had late-stage disease.It is not entirely clear whether the rising CRC rates reflect a true anthropomorphic change in disease epidemiology or an artifact of suboptimal data. Relatively recent local expansion of healthcare services, improvements in disease diagnosis, and better capture of population health data may more accurately characterize CRC incidence than in the past. Alternatively, recent CRC incidence rates may reflect inaccurate population estimates because of data limitations. As the authors note, only 23 of 47 ssAfrica nations have a formal cancer registry system. Furthermore, the registries that do exist are limited and of variable quality.
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We recognize as well that true population size can be difficult to determine, the accuracy of reported CRC diagnoses can vary, and existing registries may not capture all CRC cases.If the recent increase in CRC incidence is real, there are several potential contributors. Environmental factors have received considerable attention as LMICs adopt diet and lifestyle practices similar to high-income countries.
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Alongside economic and social development, there has been a nutrition transition in ssAfrica, characterized by a decrease in the consumption of starch, dietary fiber, and plant proteins and an increase in total fat, saturated fatty acids, and animal fats.12
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In addition, the emergence of noncommunicable chronic disease states like obesity and diabetes coupled with increased tobacco use confer a higher risk.14
Increasing life expectancy has also been believed to contribute to rising incidence rates, although the high proportion of cases under age 40 at Tenwek reflects a younger age distribution and argues otherwise.Overall, the observations from Tenwek favor a real increase and not data error or reporting bias. The CRC rates were measured in the same population, using the same methodology over time, without reliance on registries. They are supported as well by data from both East and West Africa that point to a shifting epidemiology of CRC.
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So, is it time to screen for CRC in ssAfrica? With rising disease burdens, Kenya and other resource-limited countries are considering such programs. Screening average-risk individuals is supported by both randomized and observational studies, and the introduction of universal screening has contributed to a 30-year decline in CRC incidence and mortality in the United States and Europe.
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CRC screening has also been shown to be cost-effective in LMICs in modeling studies.16
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Nonetheless, the introduction of widespread colonoscopy is limited by several factors, including patient acceptance, provider (doctors and nurses) availability, pathologic services, endoscopic training, infrastructure, and cost. Screening leads to increased diagnosis of disease, and countries will need to consider downstream access to surgical and oncologic services. In addition, endoscopy in many parts of the world is cost-prohibitive, and facilities must recognize that patient safety may be a concern if equipment is not processed, maintained, and serviced regularly.What options exist? The fecal immunochemical test is the most common CRC screening test globally and should be a strong consideration in LMICs. Implementation of a fecal immunochemical test screening program only requires colonoscopy services for the 5% to 12% of patients with an abnormal (ie, positive) result. In addition, flexible sigmoidoscopy and other more recently adopted technologies like serologic blood tests for CRC screening might also be valuable and cost-effective. Some of these strategies have been implemented in India and other LMICs but have not been evaluated for feasibility or cost in ssAfrica. There is also an evolving interest in laboratory-based, big-data approaches as well as lower-cost endoscopic technologies. The next decade may offer a variety of additional options to either precede or enhance standard colonoscopy, improving access in underserved areas.
There is one vital consideration: Regardless of what frontline screening strategy is used, the need for endoscopic services will increase. All abnormal results of noncolonoscopic screening require a follow-up colonoscopy. Current endoscopic capacity is low in ssAfrica, and any increase in availability will require parallel growth in infrastructure, training (endoscopists, nurses, technicians), and ancillary services (pathology). Given the lack of trained gastroenterologists and endoscopists in ssAfrica, countries may need to train individuals from other specialties as well as nonphysician providers to meet demand.
The American Society for Gastrointestinal Endoscopy has supported endoscopy training for physicians and nurses through the Ambassador Program, established in 2010 in support of endoscopic medical care and training in developing countries. Because of funding limitations the program is no longer active; however, a few organizations and academic institutions in the United States, Canada, the United Kingdom, and other countries continue to offer endoscopic training throughout ssAfrica. Manufacturers of endoscopic equipment have also partnered with hospitals in ssAfrica to loan or donate equipment. Such efforts are instrumental in assisting nations that lack endoscopic training, resources, and personnel. Although face-to-face training will likely remain a mainstay, remote training and continuing education through live video and e-courses might supplement these efforts. As countries like Kenya consider the implementation of CRC screening and diagnostic services, they will need additional input from international medical societies, academic medical institutions, and equipment suppliers to meet national goals.
As the study elaborates, improved CRC screening capacity in LMICs is an increasingly critical need. Social and economic advancement, nutritional transition, lifestyle, and environmental factors are all likely contributors to the rising incidence of CRC (and other malignancies). Although cancer prevention is not yet a public health priority in most of ssAfrica, publications like that of Parker et al
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emphasize the need for more innovative and expansive approaches to rising incidence and worsening outcomes. With a committed, coordinated, and comprehensive approach and by aligning training, infrastructure, and technology, the potential for impact is massive, and the door is wide open.Disclosure
The authors disclosed no financial relationships relevant to this publication.
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- Colorectal cancer is increasing in rural Kenya: challenges and perspectivesGastrointestinal EndoscopyVol. 89Issue 6
- PreviewColorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer death.1,2 Although CRC incidence and mortality are decreasing in some high-income countries (HICs),3 CRC rates in low- and middle-income countries (LMICs) are increasing.4 Historically, CRC was thought to be an uncommon diagnosis in much of sub-Saharan Africa, attributed to the presence of a high-fiber diet.5 Although reliable data from sub-Saharan Africa are limited,4,6 there does appear to be a recent increase in CRC rates6 (Table 1).
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