The prognostic value of the metastatic lymph node ratio and maximal metastatic tumor size in pathological N1a papillary thyroid carcinoma

Abstract

Objective: The presence of central neck lymph node (LN) metastases (defined as pN1a according to Tumor Node Metastasis classification) in papillary thyroid cancer (PTC) is known as an independent risk factor for recurrence. Extent of LN metastasis and the completeness of removal of metastatic LN must have an impact on prognosis but they are not easy to measure. Moreover, the significance of the size of metastatic tumors in LNs has not been clarified. This study was to evaluate the impact of the extent of LN metastasis and size of metastatic tumors on the recurrence in pathological N1a PTC. Design: This retrospective observational cohort study enrolled 292 PTC patients who underwent total thyroidectomy with central neck dissection from 1999 to 2005. LN ratio was defined as the number of metastatic LNs divided by the number of removed LNs, which was regarded as variable reflecting both extent of LN metastasis and completeness of resection, and LN size as the maximal diameter of tumor in metastatic LN. Results: The significant risk factors for recurrence in univariate analysis were large primary tumor size (defined as larger than 2 cm), high LN ratio (defined as higher than 0.4), and presence of macrometastasis (defined as larger than 0.2 cm). Age, sex, clinical node status, and microscopic perithyroidal extension had no effect on recurrence. In multivariate analysis, high LN ratio and presence of macrometastasis were independent risk factors for recurrence. Conclusion: LN ratio and size of metastatic nodes had a significant prognostic value in pathological N1a PTC. We suggest that risk stratification of pathological N1a PTC according to the pattern of LN metastasis such as LN ratio and size would give valuable information to clinicians.

Prognostic value of lymph node ratio in metastatic papillary thyroid carcinoma

“…After critical examination, nine studies were considered adequate according to the inclusion criteria. [18][19][20][21][22][23][24][25][26] These nine studies were published between 2012 and 2016. All studies were retrospective.…”

“…The patients' characteristics are summarised in Table I. A significant association was found between lymph node ratio and worse recurrence-free survival in 60 per cent and 75 per cent of the studies that investigated the effect of central compartment metastases 19 Lang et al 20 Schneider et al 21 Ryu et al 22 Chang et al…”

“…17 Multiple recent studies have evaluated the prognostic value of lymph node ratio in papillary thyroid carcinoma regarding loco-regional recurrence and survival, with varying results. [18][19][20][21][22][23][24][25][26] This study aimed to review recent publications addressing the prognostic value of lymph node ratio in metastatic papillary thyroid carcinoma.…”

“…[19][20][21][22][23][24][25][26] Different lymph node ratio thresholds were used in each study (range, 0.3-0.86). The prognostic values of lymph node ratio and the hazard ratios for loco-regional recurrence are presented in Table II.…”

Papillary thyroid carcinoma, evaluation of prophylactic central compartment’s dissection versus conservative management: a prospective study

“…Besides providing objective information about LN status, CLND has also value to reduce postoperative Tg levels and local recurrence rates. 10,11 Secondary benefit of pCLND would be minimizing patients' anxiety about a secondary operation. 2 Add to this the low accuracy of preoperative diagnostic tools in identifying nodal involvement, led several authors to consider CLND especially when dealing with recurrent disease.…”