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How Many Nodes to Take? Lymph Node Ratio Below 1/3 Reduces Papillary Thyroid Cancer Nodal Recurrence
Rachel E Weitzman1, Natalie S Justicz1, Dipti Kamani1
1Department of Otolaryngology - Head & Neck Surgery, Thyroid and Parathyroid Endocrine Surgical Division, Harvard Medical School, Massachusetts Eye and Ear, Boston, Massachusetts, USA.
Introduction:
Papillary thyroid carcinoma (PTC) accounts for the majority of thyroid malignancies; risk of PTC recurrence over a 30-year period is approximately 30%, of which 70% occur as nodal metastases. Patients with nodal disease who are treated with therapeutic dissection are at higher risk for recurrence, but optimal nodal yield has not been defined. We aim to determine variables predictive of nodal recurrence of PTC within the first 5 years of surgery, with a focus on lymph node ratio (LNR), to inform clinical decision-making.
Methods:
Retrospective chart review identified 41 patients with nodal recurrence of PTC and 284 without nodal recurrence following thyroid surgery from 2000 to 2015. Cohorts were compared with regards to clinical history, surgical findings, and tumor characteristics.
Results:
The fraction of the patients who underwent therapeutic central or lateral lymph node dissection was significantly higher in the nodal recurrence cohort. Maximum tumor size, presence of extrathyroidal extension, largest lymph node focus, LNR, postoperative thyroglobulin level, and administration of postoperative radioactive iodine were significantly increased in the PTC nodal recurrence group. LNR greater than 0.3 held the highest level of significance as a binary cutoff and captured the larger proportion of patients in the nodal recurrence cohort (68.3%).
Conclusion:
This study demonstrates characteristics to help assess risk of nodal recurrence of PTC and suggests LNR of lower than 0.3 is optimal to reduce risk of recurrence. The next steps include cohort studies to validate findings and weight variable analysis to optimize the extent of surgical therapeutic dissection.
Level Of Evidence:
4 Laryngoscope, 132:1883-1887, 2022.
Insights
Papillary thyroid carcinoma (PTC) nodal recurrence risk can be predicted by specific factors. A lymph node ratio (LNR) below 0.3 is optimal for reducing recurrence after thyroid surgery.
Area of Science:
- Oncology
- Surgical Oncology
- Endocrinology
Background:
- Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy.
- Nodal metastases are the primary recurrence site for PTC, occurring in 70% of recurrences.
- Optimal lymph node dissection for PTC remains undefined.
Purpose of the Study:
- To identify predictors of nodal recurrence in PTC within 5 years of surgery.
- To evaluate the significance of lymph node ratio (LNR) in predicting PTC recurrence.
- To inform clinical decision-making regarding surgical extent for PTC.
Main Methods:
- Retrospective chart review of 41 patients with PTC nodal recurrence and 284 without.
- Comparison of clinical history, surgical findings, and tumor characteristics between cohorts.
- Analysis of factors including tumor size, extrathyroidal extension, LNR, and postoperative treatment.
Main Results:
- Higher rates of therapeutic lymph node dissection in the recurrence cohort.
- Significantly increased tumor size, extrathyroidal extension, largest lymph node size, LNR, postoperative thyroglobulin, and radioactive iodine use in the PTC nodal recurrence group.
- LNR > 0.3 was a highly significant predictor, capturing 68.3% of recurrence cases.
Conclusions:
- Specific characteristics can help assess PTC nodal recurrence risk.
- An LNR < 0.3 is suggested as optimal for reducing recurrence risk.
- Further validation studies and analysis are needed to optimize surgical dissection extent.
