Introduction: Thyroid cancer is reported as the most rapidly increasing and third-most common cancer among females. This study aimed to evaluate the data related to thyroid cancer in Kermanshah, Iran, for the first time. Materials and Methods: The data of thyroid cancers were obtained between March 2008 and March 2017. Tumors were classified into four groups: papillary, follicular, medullary, and anaplastic; age was divided into two groups (<45 years and ≥45 years); and tumor size was divided into three groups (≤2, 2–4, and >4 cm) according to the National Comprehensive Cancer Network guidelines for patients: Thyroid cancer, version 1, 2017. Results: A total of 296 thyroid cancer patients with the mean age of 41.1 years, 75% of whom were female, were studied. Most patients (89%) had papillary thyroid cancer. Of all patients, 8.8%, 21.3%, 20.6%, 27%, 5.7%, and 16.9% of patients had extrathyroidal invasion, lymph node metastasis, capsular invasion, Hashimoto's thyroiditis, distant metastasis, and goiter, respectively. With regard to the stage, 82.4% of patients had Stage I. There were significant differences between the two genders in the mean age and Hashimoto's thyroiditis. There were significant differences between the two age groups in sex and Hashimoto's thyroiditis. In addition, there were significant differences between tumor size group and laterality and vascular invasion. Conclusions: The mean age and female/male ratio in this study were similar to those of other areas of Iran. Papillary thyroid carcinoma is the most common kind of thyroid cancer in Iran. In addition, more attention should be paid to the role of Hashimoto's thyroiditis in Iranian patients with thyroid cancer in the future.

Introduction

Cancer is a major public health problem in the world and has remained one of the leading causes of death in many countries.[1] Thyroid cancer is the most common malignancy of endocrine system with an incidence continuing to increase in the recent decades.[2] According to data recorded, more than 213,000 new cases of thyroid malignancy are registered annually in the world, causing approximately 35,000 deaths each year.[3] The incidence rate of thyroid carcinoma is estimated to be 2.20/100,000 people/year in Iran.[3] Thyroid cancer is reported as the most rapidly increasing and third-most common cancer among women.[4],[5],[6] Women are affected more frequently than men, with ratios of 2:1–4:1.[7] The type of tumor is an important prognostic factor for thyroid carcinoma. Papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), medullary thyroid carcinoma (MTC), and anaplastic thyroid carcinoma (ATC) are pathological subtypes of thyroid cancer. Thyroid cancers have remarkably different features.[8] PTC is the most common kind of thyroid cancer.[8] PTC accounts for nearly 80% of all thyroid malignancies.[9] PTC is able to metastasize to the lymph nodes (LNs) during the early stages of the disease, and nodal metastasis can consequently increase the cancer-specific mortality and locoregional recurrence rates.[10],[11] FTC is the second-most common type of thyroid malignancy that accounts for nearly 20% of all thyroid cancers. The 10-year disease-specific survival of patients with FTC has been found to be 85%–92% in retrospective series.[11] MTC constitutes 5% of thyroid cancers; however, it causes 13% of all thyroid cancer-related deaths. There has been an increase in the incidence of MTC over the past 30 years with a diagnosis of smaller tumors.[12] ATC is more rare and accounts for <5% of all thyroid tumors, but more than 50% of all thyroid cancer deaths with 93.5 days' survival occurs in a series of 34 patients.[13] Histopathologic subtypes of thyroid cancer have been shown to differ in clinical features and genetic determinants. Epidemiological features of thyroid cancer are important to clinicians. Thyroid cancer shows considerable ethnic and geographic variation and has not revealed consistent patterns. Furthermore, the pathologic characteristics of tumors are important. Pathologic diagnosis can help in primary treatment, better planning for prevention, and further studies. The study aimed to determine the epidemiology and clinicopathologic characteristics of thyroid cancers in the west of Iran which will help clinicians developing better diagnostic and therapeutic modalities. The aim of this study was performed to provide the data related to thyroid cancer in Kermanshah, Iran (a city located in the west of Iran), for the first time.

Materials and Methods

This study was approved by the Ethics Committee of Kermanshah University of Medical Sciences, Kermanshah, Iran. The data were obtained from the thyroid cancer patients admitted between March 2008 and March 2017. All cases were enrolled in this study from Imam Reza Hospital in Kermanshah, Iran. This hospital is the main training center of pathology in the west of Iran. Histological reports were screened for thyroid cancers. Various clinicopathologic and prognostic factors were described in this study such as pathologic type of the thyroid cancer, age, gender, tumor size, extrathyroidal extension, laterality, and LNs status. Tumors were classified into four groups: papillary, follicular, medullary, and anaplastic; age was divided into two groups (<45 years and ≥45 years); and tumor size was divided into three groups (≤2, 2–4, and >4 cm). These divisions were done based on the National Comprehensive Cancer Network (NCCN) guidelines for patients: thyroid cancer, version 1, 2017 (available online at NCCN.org/patients).

The data were analyzed by SPSS software (version 22.0, IBM Corp., Armonk, NY, USA) using t-test and Chi-square test to compare quantitative/numeric and qualitative/categorical variables, respectively. P < 0.05 was considered to be statistically significant.

Results

A total of 296 thyroid cancer patients with the mean age of 41.1 years (range, 1–93 years), 75% of whom were female, were studied [Table 1]. Most patients (89%) had papillary thyroid cancer. The mean tumor size in the patients was 2.2 cm (range, 0.1–16 cm). Among all patients, 8.8%, 21.3%, 20.6%, 27%, 5.7%, and 16.9% had extrathyroidal invasion, LN metastasis, capsular invasion, Hashimoto's thyroiditis, distant metastasis, and goiter, respectively. With regard to the stage, 82.4% of patients had Stage I, followed by Stages II, III, and IV. The right side had the highest laterality in the patients (54.1%), followed by the left side, and bilateral tumor. Among 263 patients, 11% had follicular variant, and among 287 patients, 16.7% had vascular invasion.{Table 1}

The distributions of age and tumor size among patients with thyroid cancer are shown in [Figure 1]. Most patients were in the age range of 20–40 years and had the tumor size of ≤2 cm.{Figure 1}

[Table 2] presents the comparison of variables between male and female patients. There were significant differences between the two genders in the mean age (P = 0.020) and Hashimoto's thyroiditis (P = 0.016). The mean age was higher in male patients than in female patients, and the prevalence of Hashimoto's thyroiditis was higher in the female patients than in the male patients.{Table 2}

The comparison of some variables based on the age group (<45 years vs. ≥45 years) is shown in [Table 3]. There were significant differences between the two age groups in sex and Hashimoto's thyroiditis. The prevalence of male patients was higher in the age group ≥45 years than the age group <45 years. In addition, the prevalence of Hashimoto's thyroiditis was higher in the age group <45 years than the age group ≥45 years.{Table 3}

Tumor size was divided into three groups (≤2 cm, 2–4 cm, and >4 cm). [Table 4] shows the comparison of some variables between these groups. The prevalence of bilateral tumor in size ≤2 cm was the lowest, followed by the right side in size 2–4 cm and the left side in size >4 cm (P = 0.043). In addition, the prevalence of vascular invasion was the lowest in size ≤2 cm and the highest in size 2–4 cm compared to other groups (P = 0.003).{Table 4}

Discussion

Thyroid nodule is a common endocrine disorder with the frequency being continuously increased worldwide.[14] Thyroid cancer is the fifth most common cancer in women in the U. S.[15] and the third prevalent cancer throughout the world.[4],[5],[6] According to reports, thyroid cancer is seen in approximately 1% of all new cancers, and 0.2% of cancer deaths occur in the U. S.[7] Recent studies have shown that the frequency of thyroid cancer is steadily increasing in the world.[8],[16] However, the frequency of thyroid cancer has decreased in few countries such as Norway and Sweden.[17] Thyroid cancer can occur at any age. In the present study, the mean age of patients was 41.1 years, and the highest number of patients belonged to the age range <45 years. The mean age was in consistent with the study conducted in Yazd, Iran. They found the mean age of 41.91 years, but their patients were equally distributed in two age groups of more or <40 years.[18] In the study of Taghavi Kojidi et al. in Iran, the prevalence of thyroid cancer was the highest in patients over 70 years.[19] Another study showed the highest number of patients were in the age group younger than 30 years.[20] Some of these discrepancies may be due to different age groups of patients in different studies. Better judgment will be possible if pathological subtypes are taken into account. The female/male ratio of thyroid cancer in this study was 3/1, which was consistent with the previous surveys in Iran and other countries.[21],[22],[23] The frequency of PTC has been estimated to increase while the frequency of FTC and MTC has remained relatively stable and that of ATC has declined.[8] Furthermore, the frequency of thyroid cancer is variable among different countries, which is directly linked to decisions made concerning the diagnosis and treatment. Among 296 patients in our study, papillary carcinoma was the most frequent one with a frequency of 89%, followed by follicular, medullary, and anaplastic carcinomas (8%, 1.7%, and 1.4%, respectively). PTC was more frequent in the current study than in other studies in Iran.[21],[24],[25],[26] However, there are studies in the United States, France, and Japan that have demonstrated a higher prevalence for PTC than our study (>90%).[27],[28],[29] About 11% (29 cases) of papillary carcinomas had follicular variant, which was diagnosed histologically.

The high variation in thyroid cancer in geographic areas found in different studies originates from the genetic, environmental, and lifestyle factors. Access to medical care is also a determinant.[14] LNs invasion, extrathyroid invasion, capsular invasion, and vascular invasion have been observed with prevalence rates of 21.3%, 8.8%, 20.6%, and 16.7%, respectively. Lee et al. reported higher capsule invasion and extrathyroidal extension than our study.[10] In addition, they showed a statistically significant difference in central LN metastasis (P = 0.005), capsular invasion (P = 0.0001), and extrathyroidal extension (P = 0.005).

LNs metastasis is an important determinant of the prognosis of PTC.[30] Lymphatic invasion is associated with metastasis to nodes in the central or lateral compartments.[31] The present study demonstrated LNs invasion in 21.3% of cases. We did not find any significant difference in LN metastasis between both age groups and genders. Meanwhile, larger tumor size was not statistically associated with a higher risk for LN metastasis. It means that small tumors ≤2 cm have a risk of metastasis, so better evaluation of suspicious thyroid nodules and faster treatment even in small tumors are suggested accordingly. Most patients in both genders were in Stage I. The number of cases decreased with a rise in the Stage from I to IV. This may be due to more sensitive imaging techniques or awareness of the population of significant thyroid nodules and seeking diagnosis and treatment. The fine-needle aspiration is routinely done and educated in this center and is routinely used for diagnosis of suspicious thyroid lesions.

Hashimoto thyroiditis was frequently noted adjacent to thyroid cancers with significant association in young women. Evidently, autoimmune disorders, including Hashimoto thyroiditis in both acute and chronic phases are more frequent among women.[32] We found most tumors on the right thyroid lobe with statistically significant association with tumor size. Dellal et al.[33] found more laterality in the right side in both exophytic and nonexophytic nodules but with no evaluation for P value. It seems that a higher number of cases and more definite identification of laterality and multifocality versus unifocality are needed to gain better insight into this matter.

Conclusions

This study reported the data of thyroid cancer in Kermanshah, Iran, for the first time. The mean age and female/male ratio in this study were similar to other areas of Iran. PTC is the most common kind of thyroid cancer in Iran. In addition, the role of Hashimoto's thyroiditis in Iranian patients with thyroid cancer should be taken into consideration in the future. The differences between Iranian studies can be due to different genetic, environmental, and lifestyle factors.

Acknowledgment

The authors would like acknowledge Vice-Chancellor for Research and Technology, Kermanshah University of Medical Sciences and the Clinical Research Development Center of Imam Reza Hospital in Kermanshah.

Financial support and sponsorship

The study was financially supported by the Kermanshah University of Medical Sciences (grant number 96461).

Conflicts of interest

There are no conflicts of interest.