Environmental mineral density and thyroid malignancy: A multicenter cross-sectional study

Several trace minerals have been shown to be associated with thyroid cancer. Democratic Republic of Congo (DRC) is deemed the most mineral-rich country globally. Data on the characteristics of thyroid nodules in various mineral-rich regions of the DRC is scarce.

To analyze the differential spectrum of thyroid nodules based on locoregional variance in mineral density.

We conducted a cross-sectional study on 529 patients with thyroid nodules residing in Katanga, South Kivu and Kinshasa between 2005 and 2019. Of these three provinces, Katanga and South Kivu have the highest mineral density with the DRC.

Mean patient age was 44.2 years ± 14.6 years with a female predominance, with a female to male ratio of 5.4. The 66.5% of patients had a family history of thyroid disease. Total 74 patients had simple nodules, and the remaining 455 patients had multiple nodules. The 87.7% of patients were euthyroid. The nodules exhibited varying characteristics namely hypoechogenicity (84.5%), solid echostructure (72.2%), macronodular appearance (59.8%), calcifications (14.4%) and associated lymphadenopathy (15.5%). The 22.3% of the nodules were malignant. Factors independently associated with malignancy were older age (≥ 60 years) [adjusted odds ratio (aOR) = 2.81], Katanga province (aOR = 8.19), solid echostructure (aOR = 7.69), hypoechogenicity (aOR = 14.19), macronodular appearance (aOR = 9.13), calcifications (aOR = 2.6) and presence of lymphadenopathy (aOR = 6.94).

Thyroid nodules emanating from the mineral-laden province of Katanga were more likely to be malignant. Early and accurate risk-stratification of patients with thyroid nodules residing in high-risk areas could be instrumental in optimizing survival in these patients.