In line with the results of our study, YuJiao Deng and colleagues evaluated the global burden of thyroid cancer from 1990 to 2017 and demonstrated that the incidence of thyroid cancer was positively correlated with SDI, while the mortality rate of this cancer was significantly inversely correlated with SDI [
34]. Another study conducted in 204 countries in 2021 also showed that the global incidence of this cancer continued to increase over the last three decades. One of the most important risk factors associated with thyroid cancer in countries with high SDI is elevated body mass index (BMI) [
35]. Azadnajafabad et al. performed a systematic review in 2021 and showed that countries with higher socioeconomic status displayed the highest incidence and lowest mortality rates of thyroid cancer, which complied with the results of our study. This is probably due to better access to health care and early diagnosis in these countries [
36]. Previous studies have shown that the increased incidence of this cancer can be caused by the socioeconomic status and the level of development of a society. For example, the prevalence of thyroid cancer in African men (79 per 100,000 people) significantly differs from Australian men (365 per 100,000 people) [
10]. A study in Los Angeles showed that countries with high socioeconomic levels reported higher incidence of thyroid cancer than countries with low socioeconomic status. It is also possible that the main cause of the increase in the metastases of this cancer is the delay in providing medical and health care, which can have reducing effects on the prognosis of this cancer. Therefore, the prognosis of this cancer is more favorable in developed countries with better economic status compared to developing countries [
6]. Finally, low socioeconomic status is associated with more advanced papillary thyroid cancer at presentation and lower adjuvant radioiodine rates after total thyroidectomy, especially among patients younger than 45 years from areas with moderate household income [
37]. Also, a study was conducted to investigate the practice of radioactive iodine therapy and clinical-social factors related to radioactive iodine dose in differentiated thyroid cancer patients among Asian countries. This study showed Different radioactive iodine dose ranges are used in the low-risk group probably because the physicians consider radioactive iodine dose elevation based on clinical-social factors beyond pre-existed guidelines [
38]. Also, the influence of ethnic and geographic diversity on distinct outcomes of thyroid cancer is well documented and shows distinct and different observations in different countries. Age at diagnosis, gender, risk classification, and tumor stage influence disease progression and mortality. Survival rates were favorable for patients who received radioactive iodine treatment. In addition, adherence to institutional clinical practice guidelines leads to better disease control. Studies on the Middle Eastern population show that those residing in developing countries have a slightly lower survival rate when compared to developed countries [
39]. Consistent with the results of the present study, black patients and those with low socioeconomic status have worse outcomes for thyroid cancer. Asian-Pacific Islander and Hispanic patients may have a protective effect on survival despite having more advanced diseases [
40,
41].