Treatment of Differentiated Thyroid Cancer

Surgery

Surgery represents the first-line potentially curative treatment for patients with differentiated thyroid cancer (papillary and follicular thyroid carcinoma). The goals of surgery include:

• Complete resection (surgical removal) of the tumor
• Preserving the patient's functional speech capacity
• Preserving the patient's swallowing capacity
• Preserving the parathyroid glands during surgery
• Preserving the patient's quality of life
• Prolonging survival

There are two types of surgical procedures that may be considered in patients with differentiated thyroid cancer:

• Lobectomy - surgical procedure whereby only one lobe of the thyroid gland (the lobe containing the tumor) is removed.
• Thyroidectomy - surgical procedure whereby either most of the thyroid gland is removed (subtotal thyroidectomy) or the entire thyroid gland is removed (total thyroidectomy).

Over the years, there has been considerable debate in the medical literature about the extent of the thyroid surgery that is optimal for treating low-risk patients with differentiated thyroid carcinoma. While some surgeons believe that low-risk patients can be safely treated with a lobectomy, others advocate a more aggressive surgical approach and recommend a total thyroidectomy even for low-risk patients.

In general, many surgeons will consider a lobectomy as a surgical treatment option for patients with papillary thyroid carcinoma if the size of the tumor is less than 1.0 cm in diameter and the tumor is confined to only one lobe of the thyroid gland. Total thyroidectomy, however, is the preferred surgical procedure for papillary thyroid tumors that are larger than 1.0 cm in diameter, especially if the tumor has spread beyond the thyroid gland.

Lobectomy may also be sufficient for patients with a definitive diagnosis of minimally invasive follicular thyroid carcinoma. For patients with widely invasive follicular carcinoma, the current recommendation is total thyroidectomy.

In addition to removing the thyroid tumor during surgery, if the cancer has spread to lymph nodes near the thyroid gland or to lymph nodes in the neck, these are also usually removed at the time of surgery to prevent further spread of the cancer in the body.

The standard and most effective treatment for patients with medullary thyroid carcinoma (MTC) is a total thyroidectomy and removal of lymph nodes on both sides of the neck. The reason for this more aggressive surgical approach includes the following observations:

• MTC is usually multifocal, meaning that the cancer is present in both the right and left lobes of the thyroid gland.

• In up to 75% of patients with MTC, the cancer has already spread to the cervical lymph nodes by the time the cancer is discovered.

It is important to emphasize that surgery for thyroid cancer should be performed by a skilled thyroid surgeon. Studies have shown that patients undergoing thyroid cancer surgery have fewer complications if the surgery is done by an experienced thyroid surgeon as compared to a general surgeon.

Potential complications of thyroid surgery include:

• Vocal cord paralysis due to injury to the recurrent laryngeal nerve during the surgery
• Injury to the parathyroid glands
• Infection
• Bleeding