Missing and decayed teeth, oral hygiene and dental staining in relation to esophageal cancer risk: ESCCAPE case‐control study in Kilimanjaro, Tanzania

Abstract

In the African esophageal squamous cell carcinoma (ESCC) corridor, recent work from Kenya found increased ESCC risk associated with poor oral health, including an ill‐understood association with dental fluorosis. We examined these associations in a Tanzanian study, which included examination of potential biases influencing the latter association. This age and sex frequency‐matched case‐control study included 310 ESCC cases and 313 hospital visitor/patient controls. Exposures included self‐reported oral hygiene and nondental observer assessed decayed+missing+filled tooth count (DMFT index) and the Thylstrup‐Fejerskov dental fluorosis index (TFI). Blind to this nondental observer TFI, a dentist independently assessed fluorosis on photographs of 75 participants. Odds ratios (ORs) are adjusted for demographic factors, alcohol and tobacco. ESCC risk was associated with using a chewed stick to brush teeth (OR 2.3 [95% CI: 1.3‐4.1]), using charcoal to whiten teeth (OR 2.13 [95% CI: 1.3, 4.1]) and linearly with the DMFT index (OR 3.3 95% CI: [1.8, 6.0] for ≥10 vs 0). Nondental observer‐assessed fluorosis was strongly associated with ESCC risk (OR 13.5 [95% CI: 5.7‐31.9] for TFI 5+ v 0). However, the professional dentist's assessment indicated that only 43% (10/23) of participants assessed as TFI 5+ actually had fluorosis. In summary, using oral charcoal, brushing with a chewed stick and missing/decayed teeth may be risk factors for ESCC in Tanzania, for which dose‐response and mechanistic research is needed. Links of ESCC with “dental fluorosis” suffered from severe exposure misclassification, rendering it impossible to disentangle any effects of fluorosis, extrinsic staining or reverse causality.

Microbiome and Cancers of the Esophagus: A Review

“…Furthermore, two recent case-control studies from East Africa have shown that dental fluorosis, an irreversible hypo-mineralization of the tooth enamel characterized by brown stains and pits in severe cases, may be an important understudied risk factor contributing to ESCC risk in this high-risk region. Moderate/severe dental fluorosis was strongly associated with ESCC risk (compared with no dental fluorosis) with an OR of 14.7 (95% confidence interval (CI): 7.6–28.6) [ 76 ] and 13.5 (95% CI: 5.7–31.9) [ 85 ] in case-control studies from Kenya and Tanzania, respectively. The large effect sizes and consistent observations across these two independent studies warrant further investigations to assess how dental fluorosis may impact ESCC risk.…”

Geophagia and risk of squamous cell esophageal cancer in the African esophageal cancer corridor: Findings from the ESCCAPE multicountry case‐control studies

“…Other inherent limitations of the case‐control study design include the possibility of control selection bias and misclassification of the exposure status, as already mentioned, in particular the under‐reporting of geophagia. Strengths of the study are a large ESCC study which has already led to the identification of several risk factors 5‐7 . Further, the potential selection bias when recruiting from a capital city tertiary hospital—of hospital controls residing nearby while cases originate from afar—was minimized.…”

“…Strengths of the study are a large ESCC study which has already led to the identification of several risk factors. 5 , 6 , 7 Further, the potential selection bias when recruiting from a capital city tertiary hospital—of hospital controls residing nearby while cases originate from afar—was minimized.…”

“…4 Among these studies are the ESCC African PrEvention research (ESCCAPE) case-control studies in Kenya, Tanzania and Malawi. To date ESCCAPE results have highlighted the role of alcohol, poor oral health and hot beverage consumption, [5][6][7] while other African studies have identified dietary factors (such as daily spicy chilies and salted foods) and indoor air pollution. 8 With a multicausal etiology, a hypothesized contributor to ESCC risk in East Africa is geophagia.…”

An international report on bacterial communities in esophageal squamous cell carcinoma

“…Studies from Asia, Europe, Latin America, Kenya, and Iran have reported associations of ESCC with poor oral hygiene, chronic periodontal disease, dental decay, and tooth loss (7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Recently, three parallel case-control studies in Kenya and Tanzania, conducted as part of the African Esophageal Cancer Consortium (AfrECC) and ESCCAPE (esccape.iarc.fr) collaborations, reported possible associations of poor or infrequent oral hygiene with increased risk for ESCC in East Africa (17)(18)(19)(20).…”