Inclusion criteria were as follows. (1) Clear evaluation
of the association of cancers of the larynx or pharynx
with GERD. (2) Diagnoses of laryngeal or pharyngeal
cancer, and sources of cases and controls. (3) Explicit
details of GERD detection methodology. (4) Adequate
data for laryngeal or pharyngeal cancer cases
and controls. (5) Most recent and updated version of
published studies.
Exclusion criteria were the following. (1) Uncontrolled
studies; (2) review articles, case reports,
studies in languages other than English, and patients
with benign disease; (3) animal studies; (4) cohort
studies; (5) multiple articles providing results from
the same study.