Abstract:
Geophagia, the intentional practice of consuming soil, occurs across the African esopha geal cancer corridor, particularly during pregnancy. We investigated whether this practice
is linked to endemic esophageal squamous cell carcinoma (ESCC) in this region. We con ducted ESCC case-control studies in Tanzania, Malawi and Kenya. Cases were patients
with incident histologically/clinically confirmed ESCC and controls were hospital
patients/visitors without digestive diseases. Participants were asked if they had ever
eaten soil (never/regularly/pregnancy-only). Odds ratios (OR) are adjusted for sex, age,
tobacco, alcohol, country, religion and marital status. Overall, 934 cases (Malawi 535, Tan zania 304 and Kenya females 95) and 995 controls provided geophagia information.
Among controls, ever-geophagia was common in women (Malawi 49%, Kenya 43% and
Tanzania 29%) but not in men (10% Malawi, <1% Tanzania). In women, ESCC ORs were
1.25 (95% CI: 0.70, 2.22) for regular versus never geophagia and 0.88 (95% CI: 0.64,
1.22) for pregnancy-only versus never. Findings were stronger based on comparisons of
cases with hospital visitor controls and were null using hospital patients as controls. In
conclusion, geophagia is too rare to contribute to the male ESCC burden in Africa. In
women, the practice is common but we did not find consistent evidence of a link to
ESCC. The study cannot rule out selection bias masking modest effects. Physical effects
of geophagia do not appear to have a large impact on overall ESCC risk. Research with
improved constituent-based geophagia exposure assessment is needed.
