Lymph Node Yield in Papillary Thyroid Cancer

Sarrah Idrees¹, Firoz Ahmed², Sabaretnam Mayilvaganan^{3https://orcid.org/0000-0002-2621-394X}

¹Department of Endocrine and Breast Surgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

²Department of ENT, Ganga Ram Hospital, New Delhi, India

³Department of Endocrine Surgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Corresponding Author: Sabaretnam Mayilvaganan, Department of Endocrine Surgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India, e-mail: drretnam@gmail.com

How to cite this article: Idrees S, Ahmed F, Mayilvaganan S. Lymph Node Yield in Papillary Thyroid Cancer. Indian J Endoc Surg Res 2021;16(2):91.

Source of support: Nil

Conflict of interest: None

ABSTRACT

Papillary thyroid cancer (PTC) is the most common thyroid cancer which spreads via the lymphatic route. Lymph nodes are also the most important prognostic indicators of persistent/recurrent/progressive disease. The lymph node yield (LNY), defined as the total number of lymph nodes retrieved during dissection, has not been determined in surgical resection of PTCs, be it in adults or pediatric population.

Keywords: Endocrine cancer, Solid cystic papillary thyroid cancer, Thyroid cancer.

Papillary thyroid cancer (PTC) is the most common thyroid cancer which spreads via the lymphatic route. Lymph nodes are also the most important prognostic indicators of persistent/recurrent/progressive disease.¹ The lymph node yield (LNY), defined as the total number of lymph nodes retrieved during dissection,² has not been determined in surgical resection of PTCs, be it in adults or pediatric population.

The NCCN and ATA guidelines recommend lymph node dissection for all patients with clinically involved central compartment nodes (therapeutic) and consideration of prophylactic lymph node dissection (PCLND) for patients with advanced primary tumors or where such information might be used to plan further therapy.³

However, objective and evidence-based estimates of the adequate LNY required to determine the risk of residual occult nodal disease to help guide further treatment of patients who have undergone thyroidectomy with limited nodal sampling are missing. This is very relevant for the management of PTC, the incidence of which is increasing worldwide.

Very recently, two such studies have been done by Robinson et al.¹ and Yap et al.⁴ in the adult and pediatric population, respectively, suffering from PTC. Both studies have attempted to build advanced statistical models (truncated beta binomial distribution model) to provide empirical estimates to help determine the risk of occult nodal disease in patients with papillary thyroid cancer by as a function of primary tumor (T) stage and the number of nodes examined, using a large sample from a nationwide database of United States.

Robinson et al.¹ study estimated that in adults, six, nine, and 18 LNs would need to be retrieved to ensure a reasonably adequate LN evaluation across all clinical scenarios for patients with T1b, T2, and T3 disease, respectively. As few as three, four, and eight LNs may need to be removed in patients with T1b, T2, and T3 disease, respectively, undergoing true PCLND. These estimates are meant to help standardize the interpretation of PCLND.

Similarly, Yap et al.⁴ suggested that overall, 12 lymph nodes would be needed to estimate lymph node positivity with 90% sensitivity in the pediatric population. When LNY was estimated as a function of T-stage in children, it was found patients with larger T2 and T3 tumors, a smaller LNY of 8 and 6, respectively, can accurately determine nodal positivity with 90% sensitivity. They also found that the risks of obtaining at least 14 lymph nodes in T1 tumors outweighs the benefits of obtaining highly accurate pathologic nodal staging and thus support the practice of not performing prophylactic lymph node harvest for T1, low-risk tumors in children.

This concept of LNY in adult and pediatric population with PTC can definitely help the thyroid surgeons in planning the extent of surgery and enhancing the disease-free survival among patients.

ORCID

Sabaretnam Mayilvaganan https://orcid.org/0000-0002-2621-394X

REFERENCES

1. Robinson TJ, Thomas S, Dinan MA, et al. How many lymph nodes are enough? Assessing the adequacy of lymph node yield for papillary thyroid cancer. J Clin Oncol 2016;34(28):3434–3439. DOI: 10.1200/JCO.2016.67.6437.

2. Locca O, Farcomeni A, De Virgilio A, et al. Prognostic significance of lymph node yield and lymph node ratio in patients affected by squamous cell carcinoma of the oral cavity and oropharynx: study protocol for a prospective, multicenter, observational study. Contemp Clin Trials Commun 2019;14:100324. DOI: 10.1016/j.conctc.2019.100324.

3. Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid 2016;26(1):1–133. DOI: 10.1089/thy.2015.0020.

4. Yap A, Shui A, Gosnell J, et al. Accuracy of the lymph node yield in surgery for papillary thyroid cancer in children. World J Surg 2021;45(10):3092–3098. DOI: 10.1007/s00268-021-06207-z.

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