What is the difference between papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC)?

From the Guidelines

Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are both treated with thyroidectomy, but the approach may vary depending on the specific characteristics of the cancer, with PTC being more likely to require total thyroidectomy due to its higher likelihood of multifocality and lymph node involvement, as suggested by the most recent guidelines 1.

Key Differences in Treatment Approach

• PTC is more likely to be multifocal and bilateral, requiring total thyroidectomy, whereas FTC tends to be solitary and may be treated with lobectomy in some cases.
• The presence of lymph node metastases, extrathyroidal extension, or distant metastases influences the treatment approach, with total thyroidectomy and radioactive iodine therapy being considered for higher-risk cases.
• The use of molecular testing for diagnostic, prognostic, and predictive purposes is becoming increasingly important in the management of differentiated thyroid cancer, as highlighted in the NCCN guidelines 1.

Treatment Considerations

• Thyroidectomy is the primary treatment for both PTC and FTC, with the extent of surgery depending on the tumor size, location, and presence of metastases.
• Radioactive iodine therapy may be considered for patients with higher-risk features, such as lymph node metastases or distant metastases, to reduce the risk of recurrence and improve survival.
• The management of thyroid cancer requires a multidisciplinary approach, involving endocrinologists, surgeons, radiologists, and nuclear medicine specialists, to ensure optimal outcomes and minimize morbidity and mortality.

Recent Guidelines and Recommendations

• The NCCN guidelines 1 provide recommendations for the management of thyroid carcinoma, including the use of molecular testing, the role of surgery and radioactive iodine therapy, and the importance of risk stratification in determining the treatment approach.
• The guidelines emphasize the need for individualized treatment planning, taking into account the specific characteristics of the cancer, the patient's overall health, and the potential risks and benefits of different treatment options.

From the Research

Overview of Papillary and Follicular Thyroid Carcinoma

• Papillary thyroid cancer (PTC) is the most common thyroid malignancy, with an excellent prognosis and overall survival rate of more than 90% 2.
• Follicular carcinomas of the thyroid are differentiated carcinomas developed from the follicular epithelium, keeping some of its morphological and functional characteristics 3.
• The long-term survival rate for papillary and follicular carcinoma is more than 90%, but this varies considerably among subsets of patients 4.

Treatment Options

• The first-line treatment for PTC is surgical excision, with total thyroidectomy being the preferred approach for most patients 2, 3.
• Total thyroidectomy optimizes adjuvant treatment options, including radioactive iodine ablation of thyroid remnant, local recurrences, and regional or distant metastases 2.
• Thyroxine treatment is given to all patients, and follow-up is done with serum thyroglobulin (Tg) measurements and whole-body scanning 3, 4.

Comparison of Papillary and Follicular Variant of Papillary Carcinoma

• The follicular variant of papillary thyroid carcinoma (FVPTC) presents with larger tumors and higher tumor stage than pure papillary carcinoma (PTC) 5.
• FVPTC has a lower local invasion rate and recurrence rate than PTC, despite similar therapies 5.
• The prognosis of FVPTC and PTC is similar in early stages, and FVPTC may not require more aggressive therapy than PTC 5.

Extent of Surgery for Low-Risk Papillary Thyroid Carcinoma

• The adequate extent of surgery for 1-4 cm low-risk papillary thyroid carcinoma (PTC) is unclear 6.
• Adherence to the 2015 ATA Guidelines recommendation 35B could lead to a huge increase in reinterventions when a thyroid lobectomy is performed 6.
• More than half of patients who may undergo a thyroid lobectomy for a seemingly low-risk PTC would have required a second operation to satisfy international guidelines 6.