Colorectal cancer in an African city population in transition

Incidence and risk factors for colorectal cancer in Africa: a systematic review and meta-analysis

INTRODUCTION

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. There is a significant burden of mortality from colorectal cancer in Africa. Due to the heterogeneity of dietary and lifestyle practices throughout Africa, our work sought to define risk factors for the development of CRC in the African continent.

METHODS

We systematically searched PubMed, Embase, Global Health, CINAHL, Cochrane CENTRAL, and African Index Medicus for studies written in English, examining the incidence and risk factors of CRC in Africa. A systematic analysis was done to compare different risk factors in constituent studies. A meta-analysis random effects model was fitted to estimate the pooled incidence of CRC.

RESULTS

Of 2471 studies screened, 26 were included for the quantitative analysis; 20 in the incidence analysis, and six in the risk factor analysis. The overall ASIR per 100,000 person-years of CRC for males and females was 7.51 and 6.22, respectively. The highest incidence rates were observed between 2012 and 2021. Risk factors for CRC in Africa include tobacco smoking, and consumption of red meat, butter, and alcohol. Protective factors included, regular consumption of fruits and regular physical activity.

CONCLUSION

The incidence of CRC in Africa is higher than that suggested by previous studies. Our study shows that nonmodifiable and modifiable factors contribute to CRC in Africa. High-quality studies conducted on generalizable populations that examine risk factors in a comprehensive fashion are required to inform primary and secondary prevention initiatives for CRC in Africa.

Left-sided colorectal cancer distinct in indigenous African patients compared to other ethnic groups in South Africa

Introduction

A large proportion of indigenous African (IA) colorectal cancer (CRC) patients in South Africa are young (< 50 years), with no unique histopathological or molecular characteristics. Anatomical site as well as microsatellite instability (MSI) status have shown to be associated with different clinicopathological and molecular features. This study aimed to ascertain key histopathological features in microsatellite stable (MSS) and low-frequency MSI (MSI-L) patients, to provide insight into the mechanism of the disease.

Methods

A retrospective cohort (2011–2015) of MSS/MSI-L CRC patient samples diagnosed at Charlotte Maxeke Johannesburg Academic Hospital was analyzed. Samples were categorized by site [right colon cancer (RCC) versus left (LCC)], ethnicity [IA versus other ethnic groups (OEG)] and MSI status (MSI-L vs MSS). T-test, Fischer’s exact and Chi-square tests were conducted.

Results

IA patients with LCC demonstrated an increased prevalence in males, sigmoid colon, signet-ring-cell morphology, MSI-L with BAT25/26 marker instability and advanced disease association.

Conclusion

This study revealed distinct histopathological features for LCC, and suggests BAT25 and BAT26 as negative prognostic markers in African CRC patients. Larger confirmatory studies are recommended.

Risk Factors for Colorectal Adenocarcinoma in an Indigenous Population in East Africa

Introduction

The incidence of colorectal cancer (CRC) is increasing in East Africa. Changes in lifestyle and dietary changes, particularly alcohol consumption, smoking, and consumption of cooked meats with a reduction in fibre in the diet may be responsible. The objective of our study was to determine the risk factors responsible for CRC in Uganda.

Methods

We recruited 129 participants with histologically proven colorectal adenocarcinoma and 258 control participants from four specialized hospitals in central Uganda from 2019 to 2021. Controls were block matched for age (±5 years) and sex of the case participants. The risk factor variables included; area of residence, tribe, body mass index (BMI), smoking, alcohol consumption and family history of gastrointestinal cancer. We used conditional or ordinal logistic regression to obtain crude and adjusted odds ratios for risk factors associated with CRC.

Results

In bivariate analysis, case participants were more likely to be associated with urban residence (cOR:62.11; p<0.001); family history of GI cancer (cOR: 14.34; p=0.001); past smokers (cOR: 2.10; p=0.080); past alcohol drinkers (cOR: 2.35; p=0.012); current alcohol drinkers (cOR: 3.55; p<0.001); high BMI 25–29.9 kg/m² (cOR: 2.49; p<0.001); and high BMI ≥30kg/m² (cOR: 2.37; p=0.012). In the multivariate analysis, urban residence (aOR: 82.79; p<0.001), family history of GI cancer (aOR: 61.09; p<0.001) and past smoking (aOR: 4.73; p=0.036) were independently associated with a higher risk of developing CRC.

Conclusion

A family history of gastrointestinal cancer was a risk factor for CRC. While population-based CRC screening may not be feasible in low income-countries, targeted CRC screening for first-degree relatives with CRC should be considered in East Africa. Molecular genetic studies need to be carried out to determine the role of hereditary factors in our population. Prevention strategies should be adopted to avoid smoking in our population which was associated with an increased risk of CRC.

Treatment of colorectal cancer in Sub-Saharan Africa: Results from a prospective Nigerian hospital registry

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide. Mortality for CRC is improving in high income countries, but in low and middle income countries, rates of disease and death from disease are rising. In Sub-Saharan Africa, the ratio of CRC mortality to incidence is the highest in the world. This study investigated the nature of CRC treatment currently being offered and received in Nigeria.

METHODS

Between April 2013 and October 2017, a prospective study of consecutively diagnosed cases of CRC was conducted. Patient demographics, clinical features, and treatment recommended and received was recorded for each case. Patients were followed during the study period every 3 months or until death.

RESULTS

Three hundred patients were included in our analysis. Seventy-one percent of patients received a recommended surgical operation. Of those that didn't undergo surgery as recommended, 37% cited cost as the main reason, 30% declined due to personal reasons, and less than 5% absconded or were lost to follow up. Approximately half of patients (50.5%) received a chemotherapy regimen when it was recommended, and 4.1% received radiotherapy when this was advised as optimal treatment. With therapy, the median overall survival for patients diagnosed with stage III and stage IV CRC was 24 and 10.5 months respectively. Overall, we found significantly better median survival for patients that received the recommended treatment (25 vs 7 months; P < .01).

CONCLUSIONS

A number of patients were unable to receive the recommended treatment, reflecting some of the burden of untreated CRC in the region. Receiving the recommended treatment was associated with a significant difference in outcome. Improved healthcare financing, literacy, training, access, and a better understanding of tumor biology will be necessary to address this discrepancy.

Incidence of colorectal cancer in Eritrea: Data from the National Health Laboratory, 2011-2017

Introduction

Recent studies have reported a significant increase in the prevalence of colorectal cancer (CRC) in Sub-Saharan Africa (SSA). Further, several studies employing disparate modelling algorithms have projected a significant rise in the frequency of CRC cases in the region. However, lack of good quality data on multiple themes related to CRC including incidence, among others, continues to be a problem in the region. Therefore, this study was designed to collect data on the incidence of CRC in Eritrea.

Methods

We conducted a retrospective analysis using data captured between 2011 and 2017 at the National Health Laboratory (NHL) in Asmara, Eritrea.

Results

241 colorectal cases were identified in the Eritrean National Health Laboratory (NHL) database between 2011 and 2017. In the final analysis we included 94 patients confirmed cases giving an average of 18.8 patients per annum. The average age ± Standard deviation (SD) was 57.62 ± 17.14 with a male: female ratio of 58/36 (1: 1.61). The minimum and maximum age of the patients was 19 and 90 years, respectively. The rectum to colon ratio was 47/47 (1:1). The proportion of patients < 50 years in this cohort was significant. The age-standardized incidence rate (ASIR) in the study period was between 0.97 per 100 000 to 2.21 per 100 000. Similarly, the cumulative ASIR was 9.97 per 100 000. Analysis of trends did not reveal shifts over the study period (P<0.05). However, a strong correlation between incidence and age was established.

Conclusion

This study suggests that the incidence of CRC in Eritrea is relatively low. A significant number of patients were less than 50 years of age. Even then it’s our opinion that this study may underestimate the incidence of CRC.

The shifting epidemiology of colorectal cancer in sub-Saharan Africa

The perception that colorectal cancer is rare in sub-Saharan Africa is widely held; however, it is unclear whether this is due to poor epidemiological data or to lower disease rates. The quality of epidemiological data has somewhat improved, and there is an ongoing transition to western dietary and lifestyle practices associated with colorectal cancer. The impact of these changes on the incidence of colorectal cancer is not as evident as it is with other non-communicable diseases such as diabetes. In this Viewpoint, we discuss the epidemiology of colorectal cancer in sub-Saharan Africa. Colorectal cancer in this region frequently occurs at an early age, often with distinctive histological characteristics. We detail the crucial need for hypothesis-driven research on the risk factors for colorectal cancer in this population and identify key research gaps. Should colorectal cancer occur more frequently than assumed, then commensurate allocation of resources will be needed for diagnosis and treatment.

Retrospective study of colorectal cancer in Zimbabwe: Colonoscopic and clinical correlates

AIM: To compare differences in the frequency of colorectal cancer at colonoscopy in Zimbabwe according to ethnicity.

METHODS: All lower gastrointestinal endoscopic procedures performed between January 2006 and December 2011 at a gastroenterology clinic in Harare, Zimbabwe were reviewed. The demographic characteristics, clinical indications, differences in bowel preparation and the endoscopic and histological diagnoses were compared between different ethnic groups with emphasis on colorectal cancer. The clinical and demographic characteristics and the endoscopic findings were compared using the student t-test and the χ² test, while the clinical indications associated with a diagnosis of colorectal cancer were determined by logistic regression.

RESULTS: All colonoscopies and sigmoidoscopies performed in 1236 Caucasians, 460 black Africans and 109 Asians were analysed. Colorectal cancer was diagnosed more frequently in the black African patients compared to Caucasians or Asians (10% vs 3%, 10% vs 2%, P < 0.001). However, polyps were less common among black Africans (5%) compared to both Caucasians (8%) and Asians (9%) (P = 0.03). Among patients with colorectal cancer, black Africans tended to be younger than Caucasians, who were over-represented in the oldest age category; 32 % vs 2% were less than 50 years and 41% vs 78% were older than 60 years (P < 0.001). Anaemia and weight loss were associated with colorectal cancer in both black African [odds ratio (OR): 2.73 (95%CI: 1.33-5.61) and 3.09 (1.35-7.07)] and Caucasian patients [OR: 6.65 (95%CI: 2.93-15.09) and 3.47 (1.52-7.94)].

CONCLUSION: The likelihood of diagnosing colorectal cancer in patients referred for colonoscopy in Zimbabwe is at least as likely among black Africans as it is among Caucasians.

Estimating the incidence of colorectal cancer in Sub-Saharan Africa: A systematic analysis

Background

Nearly two–thirds of annual mortality worldwide is attributable to non–communicable diseases (NCDs), with 70% estimated to occur in low– and middle–income countries (LMIC). Colorectal cancer (CRC) accounts for over 600 000 deaths annually, but data concerning cancer rates in LMIC is very poor. This study analyses the data available to produce an estimate of the incidence of colorectal cancer in Sub–Saharan Africa (SSA).

Methods

Data for this analysis came from two main sources: a systematic search of Medline, EMBASE and Global Health which found 15 published data sets, and an additional 42 unpublished data sets which were sourced from the IARC and individual cancer registries. Data for case rates by age and sex, as well as population denominators were extracted and analysed to produce an estimate of incidence.

Results

The crude incidence of CRC in SSA for both sexes was found to be 4.04 per 100 000 population (4.38 for men and 3.69 for women). Incidence increased with age with the highest rates in Southern Africa, particularly in South Africa. The rates of CRC in SSA were much lower than those reported for high–income countries.

Conclusion

Few health services in SSA are equipped to provide timely diagnosis and treatment of cancer in SSA. In addition, data collection systems are weak, meaning that the available statistics may underestimate the burden of disease. In order to improve health care services it is vital that accurate measurements of disease burden are available to policy makers.