Socioeconomic inequalities in cancer mortality: Is Costa Rica an exception to the rule?

Socioeconomic inequalities in cancer mortality have been described for a range of cancers sites worldwide, using diverse measures of socioeconomic position (SEP). These studies have shown a negative social gradient where lower SEP was associated with greater odds of having cancer, particularly in men. However, there is a lack of information regarding low and middle-income countries. The objective of our study was to analyze the relationship between the socioeconomic characteristics of patients' residential districts and mortality due to cancer in Costa Rica between 2011 and 2017. An ecological study at the level of the district of residence was conducted using the multilevel mixed-effects Poisson regression. All cancer-caused deaths between January 1, 2011 and December 31, 2017 were included (n = 32,117). Eleven cancer sites were analyzed independently. The 477 Costa Rican districts were divided by area (urban/mixed/rural) and wealth using census data. All-cancer combined a significant association between cancer mortality and wealth was found. Cancer mortality was lower in the poorest as compared to the richest districts (IRRQ4 = 0.79 [0.73-0.86]). The majority of cancer sites followed a similar pattern, showing a positive social gradient. These results contradict the international literature mostly conducted in high-income countries. These findings confirmed the importance of conducting studies in middle-income countries, since the socioeconomic and cultural contexts are different from those in high-income countries, which influence the social distribution of lifestyles and risk behaviors.