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THYROID CANCER (MEDULLARY)
Can lobectomy be enough surgery for treatment of medullary thyroid cancer?
BACKGROUND
Medullary thyroid cancer (MTC) only accounts for 4% of all thyroid cancer diagnoses. However, it accounts for a larger proportion of thyroid cancerrelated deaths compared to papillary thyroid cancer, the most common type of thyroid cancer that accounts for 84% of all thyroid cancer diagnoses. Complete surgical removal of cancer is the best option for cure. However, this may be more difficult in MTC, which can spread more easily outside the thyroid gland and in which many patients have cancer already spread to neck lymph nodes at the time of diagnosis. Total thyroidectomy with central neck dissection, where the thyroid gland is entirely removed and lymph nodes in the neck are dissected and examined, is the currently recommended initial surgery for MTC. However, this approach can lead to post-surgical complications such as damaged to recurrence of laryngeal nerve and parathyroid gland, and subsequent decreased quality of life related to vocal cord problems, permanent hypocalcemia, and hypothyroidism requiring lifelong thyroid hormone replacement. Therefore, there has been interest in assessing whether a lobectomy, where only the lobe with cancer is removed, would be enough in cases of small MTC without leading to cancer-related death or cancer recurrence.
This study aimed to investigate whether total thyroidectomy and lobectomy would result in different outcomes related to cancer-related death or recurrence in early-stage MTC that is smaller than 2 cm in size and limited to thyroid gland.
THE FULL ARTICLE TITLE
Jishu JA, et al. Limited thyroidectomy achieves equivalent survival to total thyroidectomy for early localized medullary thyroid cancer. Cancers (Basel) 2024;16(23):4062; doi: 10.3390/cancers16234062. PMID: 39682246.
SUMMARY OF THE STUDY
Information on 398 patients diagnosed with stage T1 MTC (cancer size is ≤ 2cm and cancer is only in the thyroid gland) from 2000 to 2019 were collected from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) registry, which records cancerrelated information in about 28% of the U.S. population. The patients were on average 51 years old, with 65% women and 86% White race, and followed on average for 8.9 years. Among these patients, 221 patients (56%) had cancer ≤ 1cm in size (stage T1a) and 177 patients (44%) had cancer 1-2cm in size (stage T1b). A total of 280 patients (70%) had no cancer found in lymph nodes.
Of the patients who underwent surgery, 304 patients (85%) had a total thyroidectomy and 39 patients (10%) had a lobectomy. Only 46 patients (13%) had lymph node dissection, the majority of whom had total thyroidectomy. Patients who had total thyroidectomy were more likely to have lymph node involvement (35% vs 10%) and to receive chemotherapy afterwards (35% vs 10%). When comparing patients who underwent total thyroidectomy and lobectomy, there were no significant differences in MTC recurrence (0.3% vs 0%), overall death rate (13% vs 13%), and cancer-related death rate (6% vs 8%).
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The study reported that there were no differences in risks of cancer death or recurrence between lobectomy and total thyroidectomy as the initial surgical treatment for small MTC (≤ 2cm in size without distant metastasis). There have been several other studies that suggest that lobectomy in patients with early stage MTC may be a reasonable option rather than total thyroidectomy, without increased risks of death or recurrence. Since TSH suppression or radioactive iodine therapy are not a part of routine treatment of MTC unlike in papillary thyroid cancer, total thyroidectomy does not need to be considered for these reasons. Therefore, lobectomy can be considered in certain patients with MTC after careful multidisciplinary discussion as well as shared decision making with patients. Still, long-term studies assessing impact on survival and recurrence rate as well as impact on quality of life would be needed to better inform the appropriate options for initial surgical approach for MTC. Regardless of the extent of surgery, patients with MTC should be monitored regularly with biochemical and imaging evaluation.
— Sun Y. Lee, MD
ATA RESOURCES
Thyroid Cancer (Medullary): https://www.thyroid.org/medullary-thyroid-cancer/
ABBREVIATIONS & DEFINITIONS
Medullary Thyroid Cancer: a relatively rare type of thyroid cancer that often runs in families. Medullary cancer arises from the C-cells in 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).
Cancer Metastasis: spread of the cancer from the initial organ where it developed to other organs, such as the lungs and bone.
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.
Lobectomy: surgery to remove one lobe of the thyroid.
Hypothyroidism: a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone. Treatment requires taking thyroid hormone pills.
Thyroid Hormone Therapy: patients with hypothyroidism are most often treated with Levothyroxine in order to return their thyroid hormone levels to normal. Replacement therapy means the goal is a TSH in the normal range and is the usual therapy. Suppressive therapy means that the goal is a TSH below the normal range and is used in thyroid cancer patients to prevent growth of any remaining cancer cells.
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.
Parathyroid Glands: usually four small glands located around the thyroid that secrete parathyroid hormone (PTH) which regulates the body’s calcium levels.
Hypocalcemia: low calcium levels in the blood, a complication from thyroid surgery that is usually shortterm and relatively easily treated with calcium pills. If left untreated, low calcium may be associated with muscle twitching or cramping and, if severe, can cause seizures and/or heart problems.
SEER (Surveillance, Epidemiology and End Results): a nation-wide anonymous cancer registry generated by the National Cancer Institute (NCI) that contains information on 26% of the United States population. Website: http://seer.cancer.gov
TSH: thyroid stimulating hormone – produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally.
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).
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