Published online Aug 21, 2019. doi: 10.3748/wjg.v25.i31.4512
Peer-review started: April 15, 2019
First decision: May 16, 2019
Revised: July 5, 2019
Accepted: July 19, 2019
Article in press: July 19, 2019
Published online: August 21, 2019
Processing time: 128 Days and 14.4 Hours
Esophageal cancer (EC) is associated with a poor prognosis, particularly so in Africa where an alarmingly high mortality to incidence ratio prevails for this disease. This paper aims to provide further understanding of EC in the context of the unique cultural and genetic diversity, and socio-economic challenges faced on the African continent.
The incidence rates of EC in Africa have been uptrending in contrast to those seen in other parts of the world, with some of the highest incidence rates being found in East Africa. In addition, the histological pattern of disease shows a geographic variation. There is a need for further study in order to understand the various predisposing factors leading to these trends; as well as the treatment strategies and survival outcomes.
By conducting a comprehensive review of published studies of EC in Africa, this article aims to estimate the incidence and geographic variation of EC in Africa; to determine the risk factors associated with EC in this region, as well as describing the management and treatment outcomes.
Both systematic and non-systematic systematic review methods were used. The systematic review was used to obtain data on epidemiology, risk factors, management and outcomes of EC, while the non-systematic review was to obtain incidence data from the International Agency for Research on Cancer, and the Cancer in Sub-Saharan reports. Databases including EMBASE, PubMed, Web of Science, and Cochrane Central were searched from inception to March 2019 and the list of articles retrieved was reviewed. Random effects meta-analyses models were used to assess heterogeneity between studies and to obtain odds ratio and 95% confidence intervals of the associations between EC and risk factors, incidence rate ratios for EC between sexes, and survival following treatment.
Apart from confirming well-established risk factors such as tobacco use and alcohol consumption, other associations were established - including dietary and genetic factors, socio-economic status and infections such as HIV. The age-standardized incidence rates of EC were noted to be higher in men than women, except in parts of North Africa were the rates were similar. The highest incidence rates were found to be in Malawi (30.3 and 19.4 cases /year/100000 population for males and females, respectively) followed by Kenya (28.7 cases/year/100000 population for both sexes). The best treatment outcomes were seen in patients who underwent esophagectomies and achieved overall survival rates of 76.6% at 3 years, as well as in those who underwent chemoradiotherapy and had a median patient survival time of 20 mo.
Africa has high incidence and mortality rates of EC, with preventable as well as non-modifiable risk factors, and the highest rates occurring in Malawi and East Africa. The management of this disease requires a multidisciplinary approach, and survival is significantly improved in the setting of esophagectomy and chemoradiation therapy.
Although advanced EC has a poor prognosis, a better understanding of the associated risk factors and challenges faced in managing this condition in the African setting can better inform the development of strategies and policies to improve earlier detection, optimize management and prolong survival.