April 22, 2024

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Thyroid Nodules and Cancer: Up to 68% of People Have Thyroid Nodules!

Thyroid Nodules and Cancer: Up to 68% of People Have Thyroid Nodules!



Thyroid Nodules and Cancer: Up to 68% of People Have Thyroid Nodules!

Up to 68% of People Have Thyroid Nodules! Latest JAMA Review: Which Nodules Need Surgery?

Thyroid cancer is one of the most common malignant tumors in the endocrine system, clinically mainly divided into papillary carcinoma, follicular carcinoma, undifferentiated carcinoma, and medullary carcinoma. In recent decades, the incidence of thyroid cancer has been increasing globally.

A population-based study published in 2015 in The Lancet Diabetes & Endocrinology, a sub-journal of The Lancet, showed that the incidence of thyroid cancer worldwide has almost doubled in the past 30 to 40 years.

However, despite being one of the common high-incidence cancers, the 5-year relative survival rate of thyroid cancer patients is very high, reaching nearly 98.5%.

Recently, the Journal of the American Medical Association (JAMA) published a major review summarizing the latest research evidence on the risk factors, diagnostic criteria, and treatment of thyroid cancer.

The review pointed out that papillary thyroid carcinoma is the most common type of thyroid cancer, accounting for about 84% of all thyroid cancers. Compared with well-differentiated thyroid cancers such as papillary and follicular carcinomas (which have a relatively good prognosis), poorly differentiated and undifferentiated thyroid cancers are usually more aggressive.

Although undifferentiated thyroid cancer accounts for only 1% of all thyroid cancers, it accounts for 19.9% of the causes of death related to thyroid cancer each year, and the median overall survival (OS) of these patients is only 6.5 months.

Thyroid Nodules and Cancer: Up to 68% of People Have Thyroid Nodules!

Thyroid cancer patients generally do not have symptoms. The results of a retrospective study showed that only 30% of patients had obvious symptoms at the time of diagnosis. In addition, patients with neck masses, difficulty swallowing, globus sensation (a sensation of obstruction in the throat), and hoarseness are usually more likely to have advanced thyroid cancer.

The review pointed out that childhood exposure to ionizing radiation is the strongest risk factor for papillary thyroid carcinoma. Furthermore, most of the other risk factors for thyroid cancer are unchangeable, including age, sex, race, and family history of thyroid cancer. For example, the older a person is, the higher the incidence of thyroid cancer and the poorer the survival rate; the incidence of thyroid cancer in women is three times higher than that in men.

It is worth noting that the results of a retrospective cohort study showed that patients who underwent thyroid surgery due to unilateral or bilateral thyroid nodules, large thyroid glands, or autoimmune thyroid diseases had a higher risk of thyroid cancer if their preoperative serum thyrotropin levels were higher.

7% to 15% of thyroid nodules are malignant.

Thyroid nodules can be detected during physical examination or incidentally diagnosed during imaging examinations. Research data show that 19% to 68% of randomly selected individuals can be detected with thyroid nodules through high-resolution thyroid ultrasound, and the detection rate in women (40.6% to 44.7%) is higher than that in men (27.0% to 29.9%). Currently, some guidelines believe that 7% to 15% of thyroid nodules are malignant.

The American Thyroid Association (ATA) guidelines recommend against performing biopsies on nodules smaller than 1 cm; ultrasound characteristics of the thyroid nodules will help doctors determine when patients need fine-needle aspiration. The results of a meta-analysis study (involving 39 studies, 49,661 patients, and 6 ultrasound classification systems) showed that using ultrasound characteristics (including nodule size, echogenicity, margins, vascularity, and the presence of calcifications) to detect malignant thyroid cancer, the sensitivity was 64% to 77%, and the specificity was 82% to 90%; among them, the ACR-TIRADS ultrasound classification system had the best diagnostic performance.

The review emphasizes that if a patient has thyroid nodules ≥1 cm, a biopsy should only be performed when ultrasound features suggest a malignant disease. Generally, ultrasound features that suggest malignant thyroid cancer include irregular margins, hypoechoic appearance, increased vascularity, microcalcifications, and a taller-than-wide shape on transverse section (height is the distance of the nodule from front to back, and width is the distance of the nodule from left to right). Overall, people with thyroid nodules smaller than 1 cm and those with thyroid nodules smaller than 1.5 cm without malignant ultrasound features should undergo ultrasound monitoring instead of biopsy.
Most well-differentiated thyroid cancers can be cured by surgery.

Most well-differentiated thyroid cancers (54%) have a low risk of recurrence and can be cured by surgery alone. In addition, patients with large thyroid tumors, suspected thyroid invasion, lymph node metastasis, or histological features of invasive tumors (such as medullary thyroid carcinoma, poorly differentiated thyroid carcinoma, and undifferentiated thyroid carcinoma) can undergo neck CT or magnetic resonance imaging (MRI) for evaluation. For well-differentiated thyroid carcinoma <4 cm on one side, subtotal thyroidectomy is often preferred clinically (with similar patient survival rates and fewer complications such as hypoparathyroidism compared to total thyroidectomy). For well-differentiated thyroid carcinoma ≥4 cm and bilateral thyroid carcinoma, total thyroidectomy is generally recommended.

After total thyroidectomy, radioactive iodine treatment can destroy residual thyroid tissue after surgery and hidden or inoperable metastatic lesions. Currently, it is clinically recommended that patients with a high risk of recurrence of thyroid cancer can undergo radioactive iodine treatment.


Conclusion

Currently, most well-differentiated thyroid cancers can be cured by surgery. In addition, postoperative radioactive iodine treatment can improve the overall survival rate of high-risk patients.

With the success of more anti-angiogenic multi-kinase inhibitors and targeted therapies for thyroid cancer, patients with metastatic thyroid cancer are expected to have more treatment options.

Thyroid Nodules and Cancer: Up to 68% of People Have Thyroid Nodules!

References
[1] Boucai L, Zafereo M, Cabanillas ME. Thyroid Cancer: A Review. JAMA. 2024;331(5):425–435. doi:10.1001/jama.2023.26348

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