Background
Consumption of alcoholic beverages is an established cause of seven types of cancer. Globally, an estimated 4.1% of new cancer cases in 2020 were attributed to alcohol consumption. The IARC Handbooks of Cancer Prevention programme has found sufficient evidence that, compared with continuing consumption, reduction or cessation of alcohol consumption reduces risk of cancers of the oral cavity and the oesophagus. For the other alcohol-related cancer types the evidence was limited or inadequate.
Objectives
We developed an evidence and gap map of the available studies estimating the associations of reduction or cessation of alcohol consumption with risk of each of the seven alcohol-related cancer types.
Methods
The map is based on the 83 publications that are included in the comprehensive review for the IARC Handbooks Volume 20A on Reduction or Cessation of Alcoholic Beverage Consumption and was developed using the EPPI-Reviewer and EPPI-Mapper software. The rows of the map represent reduction and cessation of alcohol consumption exposures and the columns represent each of the seven alcohol-related cancer types. At the intersection of a row and column, the corresponding number of studies is visualized and colour-coded according to study type. In addition, filters were developed to provide customized versions of the map based on selectable study characteristics such as study population and potential confounders that were included in statistical models.
Results
Among the 83 publications, which were published between 1982 and 2023, there were 120 estimates for the associations of alcohol reduction or cessation with cancer risk. Numerous research gaps were identified, for some or all cancer types. The most studied cancer sites were the oesophagus and the female breast (24 and 22 publications, respectively), whereas only 7 and 9 publications were available for laryngeal and oral cancer, respectively. Half of the publications investigated populations from the WHO Western Pacific region while 5 or less publications were available from each of the African, Eastern Mediterranean and South-East Asia WHO regions. Most studies estimated associations for alcohol cessation (76 publications), with case-control analyses being the most common. Only 13 cohort analyses estimated associations of alcohol reduction with cancer risk. Moreover, there were few studies of the associations of time since cessation, and even fewer studies accounted for potential confounding by prior amount or duration of alcohol consumption. Another important limitation of the evidence is that neither amount nor duration of smoking was included in most statistical models.
Conclusions/Implications
By enabling a visual and interactive access to a detailed overview of the available evidence, this map identifies research gaps in the epidemiological literature estimating the associations of reduction or cessation of alcohol consumption with risk of each of the seven alcohol-related cancer types. Several limitations of the current body of evidence need to be addressed by further research to strengthen the evaluations of the associations and to better inform public health efforts for reducing the burden of alcohol-related cancers.