Posthemithyroidectomy Hypothyroidism: Updated Meta-Analysis of Risk Factors and Rates of Remission

Incidence and risk factors for early thyroxin supplementation therapy after hemithyroidectomy for benign conditions in Europe. A Eurocrine® registry-based study

The incidence and risk factors of hypothyroidism after hemithyroidectomy (HT) remain poorly defined. Regarding its management, national or local policies may influence on early (first visit) prescription of replacement therapy (EPRT). Our aim was to identify factors influencing and explaining different prescription patterns across European countries. We conducted a retrospective, multicenter study using the Eurocrine® database, focusing on patients undergoing HT for histologically-proven benign conditions. Analyzed variables included the country where surgery was performed, as well as epidemiological, clinical, surgical and pathological data. The dependent variable was EPRT, assessed 30-45 days after surgery. Associations between qualitative variables and the likelihood of receiving EPRT were tested using Chi-square or Fisher's exact tests. A multivariate logistic regression model was developed to identify independent predictors. 14,484 patients undergoing HT between 2015 and 2022 were included. Median age was 52 years, and 11,345 (78.3%) were female. The most common indication for surgery was excluding malignancy in 7873 cases (54.3%). Overall, 4653 patients (32.1%) received EPRT, with significant variability among countries, ranging from 3 to 95%. Independent risk factors for EPRT included female sex, older age, malignancy and thyrotoxicosis as surgical indications, Bethesda III cytology, thyroiditis on histology, and the country where HT was performed. One-third of European patients undergoing HT for confirmed benign conditions required EPRT. That prescription was more likely among older patients, those with suspected malignancy or thyrotoxicosis as surgical indications, suspicious cytology, and thyroiditis on histology. Additionally, the country where surgery was done played a significant role.

Prevalence of and Predictive Factors for Hypothyroidism Following Hemithyroidectomy

PURPOSE

Hemithyroidectomy is an appropriate procedure that is recommended for a number of thyroid conditions to preserve the functional contralateral thyroid lobe, but patients who underwent a hemithyroidectomy still run the risk of developing hypothyroidism. This study aimed to determine the incidence of hypothyroidism following a hemithyroidectomy as well as predictive risk factors.

METHODS

A retrospective analysis was carried out on all patients who underwent hemithyroidectomy between 2016 and 2022. Age, gender, preoperative and postoperative thyroid stimulating hormone (TSH) and free thyroxin (FT4), side, and volume of the remaining lobe, as well as the histologic diagnosis, were all examined in the patients. To identify the predictors of hypothyroidism, statistical analyses, both univariate and multivariate, were conducted.

RESULTS

Out of 224 patients, 18.25% had hypothyroidism following surgery. This complication appeared within the first year in 88% of the cases. Patients with thyroiditis (P = .036), preoperative TSH levels greater than 1.72 mIU/L (P < .001), right side hemithyroidectomy (P = .017), and residual lobe volume less than 3.57 cm (P < .001) had a significantly higher risk of developing hypothyroidism.

CONCLUSION

After hemithyroidectomy, hypothyroidism is a major complication that should be carefully evaluated preoperatively based on risk factors of hypothyroidism. Furthermore, our results confirm the need for routine serum TSH monitoring for a minimum of 1 year following hemithyroidectomy.

Publicly Funded Molecular Testing of Indeterminate Thyroid Nodules: Canada's Experience

CONTEXT

Indeterminate thyroid nodules (ITNs) lead to diagnostic surgeries in many countries. The use of molecular testing (MT) is endorsed by several guidelines, but costs are limitative, especially in public health care systems like in Canada.

OBJECTIVES

The primary objective of this work was to evaluate the clinical value of ThyroSeq v3 (TSv3) using benign call rate (BCR) in a real-world practice. The secondary objective was to assess the cost-effectiveness of MT.

METHODS

This multicentric prospective study was conducted in 5 academic centers in Quebec, Canada. A total of 500 consecutive patients with Bethesda III (on 2 consecutive cytopathologies) or IV and TIRADS 3 or 4 nodules measuring 1 to 4 cm were included. MT was performed between November 2021 and November 2022. Patients with a positive TSv3 were referred for surgery. Patients with a negative TSv3 were planned for follow-up by ultrasonography for a minimum of 2 years. The BCR, corresponding to the proportion of ITNs with negative TSv3 results, was assessed.

RESULTS

A total of 500 patients underwent TSv3 testing, with a BCR of 72.6% (95% CI, 68.5%-76.5%; P < .001). Ultimately, 99.7% of patients with a negative result avoided surgery. The positive predictive value of TSv3 was 68.2% (95% CI, 58.5%-76.9%). The cost-benefit analysis identified that the implementation of MT would yield a cost savings of $6.1 million over the next 10 years.

CONCLUSION

The use of MT (TSv3) in a well-selected population with ITNs led to a BCR of 72.6%. It is cost-effective and prevents unnecessary surgeries in a public health care setting.

Thyroid Cancer: A Review

Importance

Approximately 43 720 new cases of thyroid carcinoma are expected to be diagnosed in 2023 in the US. Five-year relative survival is approximately 98.5%. This review summarizes current evidence regarding pathophysiology, diagnosis, and management of early-stage and advanced thyroid cancer.

Observations

Papillary thyroid cancer accounts for approximately 84% of all thyroid cancers. Papillary, follicular (≈4%), and oncocytic (≈2%) forms arise from thyroid follicular cells and are termed well-differentiated thyroid cancer. Aggressive forms of follicular cell-derived thyroid cancer are poorly differentiated thyroid cancer (≈5%) and anaplastic thyroid cancer (≈1%). Medullary thyroid cancer (≈4%) arises from parafollicular C cells. Most cases of well-differentiated thyroid cancer are asymptomatic and detected during physical examination or incidentally found on diagnostic imaging studies. For microcarcinomas (≤1 cm), observation without surgical resection can be considered. For tumors larger than 1 cm with or without lymph node metastases, surgery with or without radioactive iodine is curative in most cases. Surgical resection is the preferred approach for patients with recurrent locoregional disease. For metastatic disease, surgical resection or stereotactic body irradiation is favored over systemic therapy (eg, lenvatinib, dabrafenib). Antiangiogenic multikinase inhibitors (eg, sorafenib, lenvatinib, cabozantinib) are approved for thyroid cancer that does not respond to radioactive iodine, with response rates 12% to 65%. Targeted therapies such as dabrafenib and selpercatinib are directed to genetic mutations (BRAF, RET, NTRK, MEK) that give rise to thyroid cancer and are used in patients with advanced thyroid carcinoma.

Conclusions

Approximately 44 000 new cases of thyroid cancer are diagnosed each year in the US, with a 5-year relative survival of 98.5%. Surgery is curative in most cases of well-differentiated thyroid cancer. Radioactive iodine treatment after surgery improves overall survival in patients at high risk of recurrence. Antiangiogenic multikinase inhibitors and targeted therapies to genetic mutations that give rise to thyroid cancer are increasingly used in the treatment of metastatic disease.