Thyroid Cancer and Iodine Deficiency Status: A 10-Year Review at a Single Cancer Center in Tanzania

Objective: To highlight the magnitude and distribution of thyroid cancer at the largest cancer center in Tanzania and to correlate patient region of residence with regions of dietary iodine adequacy and deficiency in the country. Study Design: A retrospective cross-sectional chart review to characterize patients with thyroid cancer and regions of residence. Setting: Ocean Road Cancer Institute (ORCI), the largest cancer center in Tanzania. Subjects and Methods: Subjects had histologically confirmed thyroid cancer and no history of cancer treatment. Between January 2006 and April 2016, the cases of 139 consecutive patients with thyroid cancer at ORCI were retrospectively reviewed. Patients were grouped into those from iodine-adequate and iodine-deficient regions, based on the Tanzania demographic and health survey. Results: Patients’ median age was 47 years (range, 17-73 years), and the male:female ratio was 1:5. The number of people with thyroid cancer seen at ORCI increased steadily during the study period, with no significant difference between papillary (46%) and follicular (45%) diagnoses. Nonpapillary cancers occurred more frequently among males and patients ≥45 years of age, but these did not reach statistical significance. Seventy-five percent of all thyroid cancers were from areas of iodine deficiency, and this was similar in papillary and follicular cancer subtypes. Conclusion: The incidence of differentiated thyroid cancer is increasing at the largest cancer center in Tanzania, whereby papillary and follicular subtypes were significantly higher in regions with long-standing dietary iodine deficiency.