Lateral Neck Involvement May Predict Survival In Papillary Thyroid Cancer
*Mohammed W Jeraq, *Michelle Mulder, *Omar Picado, *Onur Kutlu, *Josefina C Farra, John I Lew
University of Miami, Miami, FL
OBJECTIVE(S): Lymph node involvement in papillary thyroid cancer (PTC) is relatively common. Although studies report number of diseased lymph nodes (LN) for malignancy or lymph node ratio (LNR) may have a prognostic value for PTC, the clinical significance of location from which these positive LN are excised remains unclear. This study evaluates the impact of lateral neck involvement (LNI) on survival in patients with PTC.
METHODS: Adult patients who underwent total thyroidectomy for PTC from National Cancer Database (NCDB) from 2010 to 2016 were studied. Patients with distant metastasis at diagnosis were excluded. Overall survival was determined by Kaplan-Meier estimates according to the number of positive LN, number of LN examined, compartment of LN involved (levels 2,3,4 for lateral vs. 6 for central), and LNR. Cox regression was used to analyze the impact of lymph node compartment involvement adjusting for known confounders of survival. Independent predictors of survival were reported as HR (95%CI) with significance set at p<0.01.
RESULTS: Of 148,377 patients with PTC and known LN status, 108,078 had no lymph node involvement. In the remaining 40,299 patients, 26,778 had central neck LN involvement only and 13,521 had LNI. Mean age was 50 years (range 18-90) and most were women (76.7%). Mean number of LN harvested were 6, with an average of 2 positive LN and an average LNR of 0.15. Median follow-up time was 42 months. Kaplan-Meier survival was independent from number of positive LN, number of LN harvested or LNR. However, in patients with LNI, worse overall survival (OS) was seen when compared to central neck LN (81% vs. 91% at 90 months, p<0.001). Multivariable survival analysis showed that LNI was associated with a higher likelihood of mortality (HR 2.55, 95% CI 2.35 - 2.76, p<0.001) relative to central neck lymph node involvement.
CONCLUSIONS: Survival following thyroidectomy in patients with PTC is lower in patients with LNI. Survival was not affected by the absolute number of LN, quantity of LN harvested or LNR. Identifying and excising involved lymph node compartments especially of the lateral neck may provide meaningful prognostic value in predicting survival.
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