Colorectal cancer survival in sub-Saharan Africa by age, stage at diagnosis, and Human Development Index: A population-based registry study Open Access

Gullickson, Cricket (Spring 2021)

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Background: Although colorectal cancer is the fifth most commonly diagnosed cancer in Africa and its burden is rising, there are limited population-level survival data for planning and assessing the effectiveness of local colorectal cancer control programs in the region. Herein, we provide the first estimates of population-based survival data for many countries in sub-Saharan Africa.   

Methods: 1,707 persons diagnosed with colorectal cancer from 2005-2015 were randomly selected from 13 population-based cancer registries operating in 11 countries (Benin, Cote d’Ivoire, Ethiopia, Kenya, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Uganda, and Zimbabwe) in sub-Saharan Africa. Vital status was ascertained from medical charts or through next of kin. 1-, 3-, and 5-years overall survival rates for all registries combined and for each registry were calculated using the Kaplan Meier estimator. Multivariable analysis was used to examine the associations of 5-year overall survival with age at diagnosis, stage, and country-level Human Development Index (HDI). All analyses were performed using Stata, and all statistical tests were two-sided and considered significant when P <0.05.

Results: Overall survival across all registries combined was 72.0% (95% CI 69.5-74.4%) at 1 year, 50.4% (95% CI 47.6-53.2%) at 3 years, and 43.5% (95% CI 40.6-46.3%) at 5 years. Factors associated with poorer survival included living within a country with lower HDI, late stage at diagnosis, and younger or older age at diagnosis (<50 or ≥70 years). For HDI, for example, the risk of death was 1.6 (95% CI 1.2-2.1) times higher for individuals residing in medium HDI countries and 2.7 (95% CI 2.2-3.4) times higher for individuals residing in low HDI countries compared to those residing in high HDI countries.

Conclusions: Survival for colorectal cancer remains considerably low in sub-Saharan African countries. Strengthening health systems to ensure access to prevention, early diagnosis, and appropriate treatment will likely be critical in improving outcomes in colorectal cancer in the region.

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Tables and Figures 

Table 1: Numbers of colorectal cancer diagnoses, included and excluded cases, and data quality indicators by cancer registry

Table 2. Patient characteristics: mean age at diagnosis, median years of follow-up, losses to follow up, and observed (all-cause) survival

Table 3. Multivariable Poisson regression models of colorectal cancer mortality in relation to country-level HDI, age at diagnosis, sex, and disease stage

Figure 1: Kaplan-Meier survival curves among colorectal cancer patients: 13 registries

Figure 2: Relative survival from colorectal cancer at 1, 3, and 5 years after diagnosis, by registry

Figure 3: Relative survival by country HDI and stage at diagnosis

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