Treatment, Clinicopathologic Patterns, and Survival of Patients Diagnosed with Thyroid Carcinoma at Tikur Anbessa Specialized Hospital Radiotherapy Unit, Addis Ababa, Ethiopia: A Retrospective Cohort Study

Solomon Hunegnaw Bezabih^1*, Wondimagegnhu Tigeneh², Eva Johanna Kantelhardt³

May 24, 2025

Abstract

Background: Thyroid carcinoma is the most common malignancy of the endocrine system, with a steadily increasing global incidence over the past three decades. According to the Addis Ababa City Cancer Registry, it is the seventh most common cancer among women. This study aimed to describe the treatment patterns, clinicopathologic features, and survival outcomes of patients diagnosed with thyroid carcinoma in Ethiopia. Materials and Methods: A retrospective cohort study was conducted involving 118 patients diagnosed between January 2016 and June 2019 at the Radiotherapy Unit of Addis Ababa University Hospital. Survival data were collected through telephone interviews. The coprimary endpoints were median survival time and associated prognostic factors.

Results

The majority of patients were female (68.6%). Papillary thyroid carcinoma (PTC, 49.2%) and Follicular Thyroid Carcinoma (FTC) were the most common histologic subtypes. Among 74 patients with Differentiated Thyroid Carcinomas (DTCs) who had an indication for radioactive iodine (RAI) therapy, only two received it. The median survival time was 41 months. Kaplan-Meier survival analysis showed that the absence of surgery, advanced T stage, and Anaplastic Thyroid Carcinoma (ATC) histology were significantly associated with reduced survival (Mantel-Cox p-values: 0.006, 0.002, and 0.041, respectively).

Conclusions

PTC and FTC are the predominant histologic subtypes of thyroid carcinoma in Ethiopia. Limited access to RAI therapy represents a significant gap in care. Poor survival was associated with lack of surgery, advanced tumor stage, and ATC histology. Efforts to improve early detection, access to high-quality thyroid surgery, and establishment of nuclear medicine facilities are urgently needed in Ethiopia.

Keywords: Thyroid Carcinoma, Retrospective Cohort Study, Survival Time, Ethiopia, Africa.

Introduction

Thyroid Carcinoma (TC), the most common cancer of the endocrine system, occurs two to three times more frequently in women than in men and is the fifth most commonly diagnosed malignancy among women globally, accounting for 5.1% of new cancer cases^[1]. While the incidence of many malignancies is declining in the Western world, the incidence of TC has continued to rise globally over the past three decades—except in Africa, where detection may be inadequate^[2]. Despite the rising incidence, TC-related mortality has remained stable at approximately 0.5 deaths per 100,000 individuals^[3]. Thyroid cancers include Papillary Thyroid Carcinoma (PTC), Follicular Thyroid Carcinoma (FTC), and Hürthle Cell Carcinoma (HTC), collectively classified as Differentiated Thyroid Carcinomas (DTCs), along with Medullary Thyroid Carcinoma (MTC) and Anaplastic Thyroid Carcinoma (ATC). In the United States, PTC accounts for 89.8% of all thyroid malignancies, followed by FTC (4.5%), MTC (1.6%), and ATC (0.8%)^[4]. In Sub-Saharan Africa, studies report PTC in 59.6% of female patients with thyroid cancer—an unexpected finding given the region’s high prevalence of iodine deficiency, which is typically associated with increased FTC rates^[5]. In Ethiopia, national-level data on thyroid carcinoma incidence are lacking. However, according to the Addis Ababa City Cancer Registry, TC is the seventh most common cancer among women^[7]. A study conducted in Gondar, northwest Ethiopia, found that PTC was the most frequent subtype, although FTC accounted for 29% of cases—significantly higher than reported in more developed countries—likely reflecting endemic iodine deficiency^[7]. Differentiated thyroid carcinomas (DTCs) generally have a favorable prognosis, whereas ATCs are highly aggressive, with disease-specific mortality nearing 100%^[8]. Poor prognostic factors related to the patient include older age (>40 years) and male sex^[8-10], while tumor-related factors include histologic type, tumor size, local invasion, necrosis, vascular invasion, BRAF V600E mutation status, and the presence of metastasis. Surgical resection remains the cornerstone and most critical component of thyroid carcinoma management. In a study conducted at the Mayo Clinic Cancer Center, patients with an AGES score of 4 or higher had poorer survival outcomes when treated with lobectomy alone compared to those who underwent bilateral resection^[17]. Postoperative administration of Radioactive Iodine (RAI) therapy with Iodine-131 has been shown to reduce recurrence and disease-specific mortality in patients at intermediate or high risk in several studies^[9,18–21]. Additionally, Thyroid Hormone Suppressive Therapy (TST) with levothyroxine has been associated with decreased recurrence rates and improved cancer-specific survival^[18,22,23]. Thyroid carcinoma is the seventh most common malignancy in Ethiopia, according to data from the Addis Ababa City Cancer Registry. Ethiopia, a country in East Africa with a population exceeding 100 million, treats numerous thyroid cancer patients across various hospitals. Tikur Anbessa Specialized Hospital (TASH) serves as the main referral center, where many patients undergo surgery and are referred to the radiotherapy unit for follow-up, adjuvant treatment, or palliative care. Adjuvant treatment options for Differentiated Thyroid Carcinomas (DTCs) typically include TST and RAI therapy. However, RAI is currently unavailable in Ethiopia, and radiotherapy is often used as a palliative measure rather than a definitive treatment. This study describes the treatment modalities and clinicopathologic patterns of thyroid carcinoma in Ethiopia. It is the first to report survival outcomes and prognostic factors among thyroid cancer patients in the country and also highlights the critical gap in adjuvant care—specifically, the unavailability of RAI therapy for patients with DTCs.

Methods and Materials

Study design, area and setting: This is a retrospective cohort study conducted in Tikur Anbessa Specialized Hospital Radiotherapy center between January 2016–June 2019 G.C. It was established in 1998 with the help of International Atomic Energy Agency (IAEA), and currently has two Cobalt-60 Teletherapy units (one out of order), one HDR Brachytherapy unit, and a LINAC under installation. The hospital includes general surgeons and one endocrine surgeon participating in multi-disciplinary thyroid cancer care. Eight full-time consultant oncologists, three medical physicists, and five radiotherapists are currently working in the center. The clinical oncology training program began in 2013, and currently, 41 residents are enrolled. Activities include inpatient admissions for chemotherapy, radiotherapy treatment, and outpatient clinics for new evaluations and follow-ups.

Population: All patients with newly diagnosed thyroid cancer registered at the radiotherapy unit of Tikur Anbessa Hospital between January 2016 and June 2019 G.C were eligible for this study.

Exclusion criteria: Patients whose phone number was not available in their medical record or those unreachable after three consecutive attempts over seven days were excluded from survival analysis.

Sample size and sampling procedure: HMIS logbooks were used to identify thyroid cancer cases evaluated at the radiotherapy unit. All eligible cases were included. A total of 118 pathologically confirmed thyroid carcinoma patients diagnosed from January 2016 to June 2019 were included in this study.

Operational definitions:
T stage: Refers to tumor size at presentation (T ≤2cm, T2 >2cm but ≤4cm, T3 >4cm or extrathyroidal extension to strap muscles, T4 = extension beyond strap muscles)^[24].
N stage: Based on lymph node status from pathology reports (N0 = no nodal metastasis, N1 = regional nodal metastasis)^[24].
Metastatic disease (M1): Presence of disease beyond thyroid and regional lymph nodes at presentation or during follow-up^[24].

Variables

The dependent variable was time to death due to thyroid cancer, measured in months. Patients who died were considered events, while those alive at the end of follow-up were censored. Explanatory variables included sociodemographic factors (age, sex), surgery-related factors (type of surgery, history of surgery, vascular invasion, capsular invasion), and tumor-related factors (T stage, N stage, metastasis, pathological subtypes, adjuvant thyroxine, serum TSH level, post-operative serum thyroglobulin level).

Data Collection Tools and Procedures

Medical records were reviewed based on HMIS logbooks. Records not meeting inclusion criteria were excluded. The supervisor discussed study goals and procedures with data collectors. A pilot chart review was conducted to ensure consistency. Regular team meetings were held to ensure data quality and resolve discrepancies.

Data Management and Quality Assurance

The principal investigator trained data collectors on standard operating procedures and supervised data collection. Completed forms were stored securely. During telephone interviews, patient details were thoroughly verified, and calls were made up to three times per day over seven consecutive days to reduce loss to follow-up.

Data Analysis

Data were entered and cleaned in SPSS version 22. Descriptive statistics such as mean, median, frequency, percentage, tables, and graphs were used. Cox regression and Log-rank (Mantel-Cox) tests assessed associations between variables. A p-value < 0.05 was considered statistically significant. Median overall survival was calculated using the Kaplan-Meier method.

Ethical Consideration

Ethical clearance was granted by the Ethical Review Board of Addis Ababa University College of Health Sciences. Verbal consent was obtained from participants during telephone interviews. Participants were informed of the study's purpose and asked for permission to provide responses.

Results

Demographic Characteristics

A total of 118 patients with pathologically confirmed thyroid carcinoma were included between January 2016 and June 2019. Most participants were female (81 patients, 68.6%), with the majority (74 patients, 62.7%) aged 21–55 years (mean age 47.8 ± 14.9 years). Forty-four patients (33.9%) were above 55 years of age. The majority came from Addis Ababa (33.6%), followed by Oromia (32.8%).

Descriptive Statistics of Presentation and Risk Factors

Among the 118 patients, 88 (72.1%) had a history of goiter, and only 3 had prior irradiation to the neck or chest wall. Nearly all patients (99.2%) had nodules undetected by ultrasound. Eight (6.6%) had a history of prior surgery for benign thyroid disease. Shortness of breath at presentation was reported in 35 patients (28.7%), dysphagia in 25 (20.5%), and hoarseness of voice in 29 (23.8%). No patients had obesity or a family history of thyroid malignancy.

Surgical and Clinicopathologic Characteristics

Clinical staging showed that 51 patients (43.2%) had T4 lesions, 19 (16.1%) had T3, and 17 (14.3%) had T1 or T2 tumors. Tumor size was unknown (Tx) in 20 patients (16.8%), and 11 (9.2%) had recurrent lesions. Surgery was not performed in 63 patients (53.4%). Among those with surgery, the type was unspecified in 21 patients (17.8%), and subtotal thyroidectomy was the most common identified procedure (18 patients).

Survival Outcomes

Survival status was successfully confirmed via telephone for all 118 patients. A total of 32 patients (27.1%) had died, with a 95% confidence interval (CI) of 17.1% to 36.8%. The median survival time was 41 months (Interquartile Range [IQR]: 36–60 months). Kaplan-Meier survival analysis showed that absence of surgery, histologic subtype, and advanced T stage were significantly associated with reduced survival. Patients who did not undergo surgery had significantly shorter survival times (log-rank p = 0.006). Histologic subtype also significantly influenced survival (p = 0.041), with differentiated thyroid carcinomas (DTCs) showing better outcomes than anaplastic (ATC) and poorly differentiated thyroid carcinomas. T stage was another significant predictor, where T4 lesions correlated with poorer outcomes (p = 0.002). Although vascular and capsular invasion initially appeared significant, their influence on survival could not be conclusively determined due to missing pathology data. In a subset analysis, neither capsular (p = 0.85) nor vascular invasion (p = 0.17) significantly affected survival time. Among histologic types, there was a statistically significant 7-month survival advantage for DTC compared to ATC (p = 0.007), and a 10-month advantage for Medullary Thyroid Carcinoma (MTC) over ATC (p = 0.045). No significant difference was observed among DTC subtypes (PTC, FTC, HCC) (p = 0.17).

Discussion

The global rise in thyroid carcinoma incidence has been attributed primarily to increased detection of subclinical disease via imaging. However, in Ethiopia, most patients presented with advanced disease—likely due to limited access to diagnostic modalities like ultrasound. In this study, 72.1% presented with goiter, none were diagnosed via routine ultrasound, and only three had a history of prior neck irradiation, a known PTC risk factor. Metastatic disease was noted in 38.1% of cases, with the lungs and bones as the most common metastatic sites, aligning with findings from Ruegemer et al. Differentiated thyroid carcinoma comprised 75.4% of all cases, with PTC accounting for 49.2%, FTC 17.8%, and HCC 5.9%. These numbers are lower than U.S. figures but consistent with studies from Ghana and other parts of Ethiopia, reflecting regional iodine deficiency. This condition may drive the higher FTC rates through chronic TSH stimulation. Most DTC cases in this cohort presented at an advanced stage: 30 patients with T4, 17 with T3, and only 16 with T1/T2 disease. This contrasts sharply with data from Mazzaferri et al., where early-stage presentation was predominant. Poor prognostic factors—including larger tumor size, T4 stage, lack of surgery, and undifferentiated histology—were significantly associated with shorter survival, underscoring the need for earlier detection and improved access to definitive therapies like radioactive iodine, which remains unavailable in Ethiopia. In this study, patients with T1 or T2 lesions were rare. Anaplastic thyroid carcinomas (ATCs) were more frequent (13.6%) compared to global reports (1–3%). This discrepancy may reflect the study setting in a radiotherapy unit, where patients often present for palliative care. Medullary thyroid carcinoma (MTC) was identified in 3 patients (2.5%), close to the global average of 1.6%. Surgery is the cornerstone of thyroid carcinoma management. However, 53.4% of patients did not undergo any surgical procedure, largely due to advanced T4 lesions or ATC diagnosis. When performed, thyroidectomy types included unspecified (17.8%), subtotal (15.3%), and total thyroidectomy (8.5%). Lobectomy alone was rare (0.8%), likely due to the scarcity of early-stage tumors. Mortality among patients with anaplastic and poorly differentiated carcinomas was 60% and 42.9% respectively—lower than some literature citing near 100% mortality but still significantly higher than among patients with DTCs (p = 0.007). Among DTC subtypes (PTC, FTC, HCC), no significant survival differences were observed (p = 0.17), and PTC generally showed favorable survival outcomes, consistent with literature. T4 lesions were significantly associated with lower survival (p = 0.002), reinforcing the importance of tumor staging. Among 74 patients for whom radioactive iodine (RAI) was indicated, only two could afford treatment abroad, highlighting a major care gap. TSH suppression therapy was administered to 71 DTC patients. A simple linear regression showed that a 1 μg increase in thyroxine dose significantly reduced TSH by 0.083 μIU/mL. Despite lacking unified national guidelines, a mean TSH < 0.1 μIU/mL was achieved in 49.2% of patients, and TSH < 1 μIU/mL in 92%. Only 4.6% achieved a TSH < 0.05 μIU/mL, the strictest recommended target for high-risk patients, suggesting the need for better optimization of TSH suppression.

Limitations of the Study

This retrospective cohort study is susceptible to inherent biases such as poor clinical documentation, inconsistent evaluations, and incomplete follow-up. The short follow-up period is another constraint, especially for DTC patients who typically have longer survival. The small sample size also limits the generalizability of findings.

Conclusions

To improve thyroid cancer outcomes in Ethiopia, the health system must prioritize establishing a nuclear medicine facility for diagnostic and therapeutic purposes, especially for radioiodine therapy. Additionally, a robust, centralized health information registry would support better tracking of patient outcomes and facilitate long-term prospective cohort studies—particularly valuable for differentiated thyroid cancers, which require extended follow-up.