Table 1 Criteria for study selection

• Human data (in vitro and in vivo studies were excluded)

• Original data (reviews, commentaries, editorials, systematic review and meta-analyses were excluded)

• Measurement of arsenic biomarkers (studies measuring arsenic in samples such as air, water, soil or any other source)

• Studies on the association between arsenic and digestive cancers, providing details about the origin of the primary cancer

• The most recent and complete article was chosen if a study had been published more than once

• Available full-text publications in English