Colorectal cancer incidence and clinicopathological features in northern Tunisia 2007–2009

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.

A systematic review of methods to estimate colorectal cancer incidence using population-based cancer registries

Background

Epidemiological studies of incidence play an essential role in quantifying disease burden, resource planning, and informing public health policies. A variety of measures for estimating cancer incidence have been used. Appropriate reporting of incidence calculations is essential to enable clear interpretation. This review uses colorectal cancer (CRC) as an exemplar to summarize and describe variation in commonly employed incidence measures and evaluate the quality of reporting incidence methods.

Methods

We searched four databases for CRC incidence studies published between January 2010 and May 2020. Two independent reviewers screened all titles and abstracts. Eligible studies were population-based cancer registry studies evaluating CRC incidence. We extracted data on study characteristics and author-defined criteria for assessing the quality of reporting incidence. We used descriptive statistics to summarize the information.

Results

This review retrieved 165 relevant articles. The age-standardized incidence rate (ASR) (80%) was the most commonly reported incidence measure, and the 2000 U.S. standard population the most commonly used reference population (39%). Slightly more than half (54%) of the studies reported CRC incidence stratified by anatomical site. The quality of reporting incidence methods was suboptimal. Of all included studies: 45 (27%) failed to report the classification system used to define CRC; 63 (38%) did not report CRC codes; and only 20 (12%) documented excluding certain CRC cases from the numerator. Concerning the denominator estimation: 61% of studies failed to state the source of population data; 24 (15%) indicated census years; 10 (6%) reported the method used to estimate yearly population counts; and only 5 (3%) explicitly explained the population size estimation procedure to calculate the overall average incidence rate. Thirty-three (20%) studies reported the confidence interval for incidence, and only 7 (4%) documented methods for dealing with missing data.

Conclusion

This review identified variations in incidence calculation and inadequate reporting of methods. We outlined recommendations to optimize incidence estimation and reporting practices. There is a need to establish clear guidelines for incidence reporting to facilitate assessment of the validity and interpretation of reported incidence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01632-7.