Dental fluorosis and oral health in the African Esophageal Cancer Corridor: Findings from the Kenya ESCCAPE case–control study and a pan‐African perspective

Abstract

There are no studies of oral health in relation to esophageal cancer in Africa, or of Eastern Africa's endemic dental fluorosis, an irreversible enamel hypo‐mineralization due to early‐life excessive fluoride intake. During 2014–18, we conducted a case–control study of squamous cell esophageal cancer in Eldoret, western Kenya. Odds ratios (AORs (95% confidence intervals)) were adjusted for design factors, tobacco, alcohol, ethnicity, education, oral hygiene and missing/decayed teeth. Esophageal cancer cases (N = 430) had poorer oral health and hygiene than controls (N = 440). Compared to no dental fluorosis, moderate/severe fluorosis, which affected 44% of cases, had a crude OR of 20.8 (11.6, 37.4) and on full adjustment was associated with 9.4‐fold (4.6, 19.1) increased risk, whilst mild fluorosis (43% of cases) had an AOR of 2.3 (1.3, 4.0). The prevalence of oral leukoplakia and tooth loss/decay increased with fluorosis severity, and increased cancer risks associated with moderate/severe fluorosis were particularly strong in individuals with more tooth loss/decay. Using a mswaki stick (AOR = 1.7 (1.0, 2.9)) rather than a commercial tooth brush and infrequent tooth brushing also independently increased risk. Geographic variations showed that areas of high esophageal cancer incidence and those of high groundwater fluoride levels have remarkably similar locations across Eastern Africa. In conclusion, poor oral health in combination with, or as a result of, high‐altitude susceptibility to hydro‐geologically influenced dental fluorosis may underlie the striking co‐location of Africa's esophageal cancer corridor with the Rift Valley. The findings call for heightened research into primary prevention opportunities of this highly fatal but common cancer.

Systematic review of esophageal cancer in Africa: Epidemiology, risk factors, management and outcomes

“…Of the 37 studies on risk factors for EC, 18 (48.6%) were conducted in South Africa[10,70-86], 5 (13.5%) in Kenya[11,13,87-89], 3 (8.1%) in Uganda[4,5,90], 2 each in Ghana (5.4%)[7,91], Zambia (5.4%)[3,92] and Zimbabwe (5.4%)[93,94], and 1 each in Malawi (2.7%)[95], Ethiopia (2.7%)[12], Tanzania (2.7%)[6], Egypt (2.7%)[96] and Nigeria (2.7%)[97].…”

“…Tooth loss, cooking, hot beverage consumption, dental fluorosis and using mursik: Tooth loss, cooking, hot beverage consumption and using mursik were found to be associated with EC in the Rift Valley of Kenya, OR 5.28, 95%CI: 2.98-9.41; OR 2.32, 95%CI: 1.41-3.84; OR 12.78, 95%CI: 6.98-23.6; and OR 3.72, 95%CI: 1.96-7.14 respectively[88]. Menya et al[11] conducted a case control study in Kenya evaluating the association of dental fluorosis and EC. They assessed association of EC with tobacco use, alcohol consumption, education, oral hygiene and missing/decayed teeth.…”

“…They assessed association of EC with tobacco use, alcohol consumption, education, oral hygiene and missing/decayed teeth. After adjusting for the other factors, they found 40% of EC cases had moderate/sever fluorosis, OR 9.4, 95%CI: 4.6-19.1 and 43 % cases with mild fluorosis, OR 2.3, 95%CI: 1.3-4[11].…”

“…Risk factors for developing ESCC include tobacco consumption (smoking)[3-5], heavy alcohol consumption[6,7], drinking hot tea[8,9], consuming red meat[10], poor oral health[11], low intake of fresh fruit and vegetables[10,12], and low socioeconomic status[6,13]. Esophageal mucosa dysplasia from acid reflux and Barrett’s esophagus is a risk factor for developing EAC[14].…”

Structural changes in the oral microbiome of the adolescent patients with moderate or severe dental fluorosis

“…It was also discovered to be associated with a particular tumor stages. Most recently, Menya 6 suggested that moderate/severe dental fluorosis was strongly associated with a 9.4-fold increased risk of esophageal squamous cell carcinoma (ESCC) compared with a no dental fluorosis population in Africa. In this study, F. nucleatum was significantly enriched in the M&S group and significantly higher than the Mild and Healthy groups.…”