Thyroid cancer is very common and carries an excellent prognosis. This is because we have very effective treatment options and we know more about identifying high risk thyroid cancers so we can target more aggressive treatment. Many thyroid cancers are small (<1-2 cm) and often are treated with removal of the lobe containing the cancer (lobectomy). Cancers >4 cm are considered high risk by the major national guidelines including the ATA cancer guidelines. These large cancers are recommended to be treated with a total thyroidectomy initially, with the recommendation of following with radioactive iodine therapy if any additional high risk feature are present. There is a higher risk of cancer recurrence and poorer prognosis associated with larger cancer due to the size, therefore, endocrinologists and surgeons feel hesitant about treating large cancers with lobectomy alone. However, there has been a shift towards more conservative surgical approaches for certain cases of thyroid cancers, particularly those with low-risk features.
This study was done to understand the clinical course and best management of large thyroid cancers. The goal was to investigate the extent of surgery needed for large thyroid cancers that do not exhibit other high risk features other than size.
THE FULL ARTICLE TITLE
Ghossein R et al 2023 Large (>4 cm) intrathyroidal encapsulated well-differentiated follicular cell-derived carcinoma without vascular invasion may have negligible risk of recurrence even when treated with lobectomy alone. Thyroid. Epub 2023 Mar 8. PMID: 36884299.
SUMMARY OF THE STUDY
This study was conducted at Memorial Sloan Kettering Cancer Center (MSKCC, New York, NY) and recruited 88 patients between 1995 and 2001. They included patients with thyroid cancers >4 cm with no other high risk features.
Only patients that had been followed up for a year or longer were considered. Some of the other parameters recorded were sex, age at diagnosis, surgery (lobectomy or total thyroidectomy), lymph nodes sampled and postoperative radioactive iodine therapy.
There was a slight female predominance observed (female to male ratio of 1.2:1) with the average age of diagnosis of 51 years. Overall, 70% of the cancers were papillary thyroid cancer, 21% of the cases were follicular thyroid cancer and 9% were oncocytic thyroid cancer. The average cancer size was 5 cm. In total, 36% of patients received a lobectomy while the rest underwent a total thyroidectomy. The average period of follow-up was 4.8 years. Lymph nodes were examined in 44% of cases and 5 of 20 cases (25%) showed spread of the thyroid cancer to the lymph nodes. All 5 of these cases underwent total thyroidectomy.
The total thyroidectomy group was more likely to have postop radioactive iodine therapy although only 34 patients received this, and they had longer follow-up. However, no difference was observed between both the groups in terms of pathological features. There was no cancer recurrence or cancer-related death noted in the entire group.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The study makes a case for more conservative surgical management options such as lobectomy/ partial thyroidectomy in cases of large (>4 cm) cancers that have no other high risk features. The risk of recurrence or cancer-related death in these cases no different than in patients with more aggressive treatment, although this is a small study. This is an important study that shows additional surgical options for these patients.
— Sargun Singh, MD and Maria Brito, MD
ABBREVIATIONS & DEFINITIONS
Thyroidectomy: surgery to remove the entire thyroid gland. When the entire thyroid is removed it is termed a total thyroidectomy. When less is removed, such as in removal of a lobe, it is termed a partial thyroidectomy.
Total thyroidectomy: surgery to remove the entire thyroid gland.
Near-total thyroidectomy: removal of nearly all of each thyroid lobe, leaving only a small portion of the thyroid gland.
Radioactive iodine (RAI): this plays a valuable role in diagnosing and treating thyroid problems since it is taken up only by the thyroid gland. I-131 is the destructive form used to destroy thyroid tissue in the treatment of thyroid cancer and with an overactive thyroid. I-123 is the nondestructive form that does not damage the thyroid and is used in scans to take pictures of the thyroid (Thyroid Scan) or to take pictures of the whole body to look for thyroid cancer (Whole Body Scan).
Lobectomy: surgery to remove one lobe of the thyroid.
Papillary thyroid cancer: the most common type of thyroid cancer. There are 4 variants of papillary thyroid cancer: classic, follicular, tall-cell and noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).
Follicular thyroid cancer: the second most common type of thyroid cancer.
Lymph node: bean-shaped organ that plays a role in removing what the body considers harmful, such as infections and cancer cells.
Cancer recurrence: this occurs when the cancer comes back after an initial treatment that was successful in destroying all detectable cancer at some point.