Differentiated thyroid cancer in SA

Dr Hunadi Molabe shares an overview of differentiated thyroid cancer in South Africa.

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Thyroid cancer, particularly differentiated thyroid cancer (DTC), represents the most common type of endocrine malignancy globally. 

DTC includes papillary and follicular thyroid cancers, which generally have a favourable prognosis and accounts for 90 – 95% of thyroid cancers. 

The epidemiology, management, and outcomes of DTC can vary significantly based on geographic and socioeconomic factors.

DTC is relatively rare (1%) compared to other cancers but has been observed to be increasing globally. This is thought to partially reflect subclinical disease (small papillary cancers that wouldn’t have caused any harm) and due to the widespread use of neck ultrasonography and other imaging modalities like CT scan, MRI, and PET scans for unrelated diseases. 

Although incidences are on the rise, mortality has remained low (0.5 per 100 000) due to the indolent nature of the disease. According to The South African National Cancer Registry, the incidence is lower compared to Western countries, but this may reflect underreporting and limited diagnostic capabilities. 

The exact incidence rate in SA is difficult to determine due to inconsistencies in data collection and reporting.

DTC typically affects more women than men and is often diagnosed in middle-aged individuals. However, the presentation can vary with age, and in SA, late-stage presentation isn’t uncommon due to delays in seeking medical care and limited access to specialised healthcare facilities, particularly in rural areas.

Most DTC have a sporadic cause (unknown) but radiation exposure (either as an environmental factor or used as previous cancer treatment), family history of thyroid cancers, and other associated thyroid cancer syndromes increases the risk.

Diagnostic challenges of differentiated thyroid cancer

Diagnosis is often delayed by several factors. Firstly, there is a lack of awareness and education about thyroid diseases among the general population and primary healthcare providers. 

Symptoms, such as a neck mass, voice hoarseness, neck lymph nodes, difficulty breathing, and inability to swallow, can be easily overlooked or misattributed to benign conditions.

The most common presentation is a thyroid nodule which can be palpable (5%) or seen on ultrasound (50%). 

Only nodules that are suspicious for cancer on ultrasound require a fine-needle aspiration cytology (FNAC) to make a diagnosis of cancer.

Secondly, diagnostic facilities are unevenly distributed, with advanced imaging (ultrasound) and FNAC being more accessible in urban centres than in rural regions. This disparity leads to delayed diagnosis and treatment initiation. Furthermore, there is a shortage of trained endocrinologists and pathologists, which exacerbates the diagnostic challenges.

Treatment approaches

Management involves a combination of surgery, radioactive iodine (RAI) therapy, and thyroid hormone suppression therapy. However, the availability and quality of these treatments can vary widely across the country.

Surgical treatment 

The first-line treatment is usually thyroidectomy (removing a lobe or whole gland – lobectomy or total thyroidectomy). However, the expertise of surgeons in thyroid cancer can vary, and in some areas, there may be limited access to experienced thyroid surgeons. This can impact the completeness of the surgery and the subsequent need for additional treatments.

Radioactive iodine therapy

RAI therapy is used post-surgery to ablate any remaining thyroid tissue or metastatic disease (spread to distant organs). Access to RAI treatment is limited by the availability of nuclear medicine facilities and the necessary infrastructure to handle radioactive materials. Patients from rural areas often have to travel long distances to receive RAI, which can pose significant logistical and financial challenges.

Thyroid hormone suppression therapy

After surgery and RAI, patients are placed on thyroid hormone suppression therapy to reduce the risk of recurrence. This requires regular follow-up and monitoring, which can be inconsistent due to healthcare access issues, especially in under-resourced regions.

Outcomes and prognosis

The prognosis for patients varies significantly based on the stage at diagnosis and the accessibility of treatment. Patients diagnosed at an early stage and who receive timely and appropriate treatment generally have an excellent prognosis, with high survival rates similar to those reported in developed countries (98% in five years). 

Unlike other cancers, DTC is still treatable even if it has spread to distant organs (bone, lung, etc.), as long as there is access to RAI.

However, patients presenting with advanced disease, which is more common in rural and underserved populations, face poorer outcomes. The late-stage presentation is often due to the aforementioned delays in diagnosis and treatment. Additionally, follow-up care is crucial for detecting recurrences, and inconsistent follow-up can negatively impact long-term survival and quality of life.

Disparity in healthcare access

DTC in SA presents unique challenges and opportunities. While the overall incidence may be lower compared to other regions, the disparity in healthcare access and resources significantly impacts patient outcomes. 

Improving awareness, enhancing diagnostic capabilities, and ensuring equitable access to treatment are critical steps towards better management of DTC in SA. Strengthening the healthcare infrastructure, particularly in rural areas, and investing in training for healthcare professionals can help bridge the gap and improve the prognosis for all patients affected by this potentially curable cancer.

This article is brought to you by Eisai Pharmaceuticals Africa.

Header image by Freepik