Size Matters: Papillary Thyroid Carcinoma Recurrence

Tumor size does indeed matter in the recurrence rate of papillary thyroid carcinoma, according to a new study.

Reference: Tran B, Roshan D, Abraham E, et al. The prognostic impact of tumor size in papillary thyroid carcinoma is modified by age. Thyroid. 2018;28:991-996.

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Bryan Tran and fellow researchers in Australia have discovered that in patients aged >55 years with papillary thyroid carcinoma experience 5 times the recurrence rate when the tumor is larger than 2 cm. Click through the slides above for details on their study and take home points for physicians.

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Papillary Thyroid Carcinoma Prognosis. While the importance of tumor size in PTC is established, there is no research investigating whether age modifies the impact of tumor size and there is conflicting evidence regarding optimal size thresholds for prognostic discrimination. Authors of the study sought answers to 3 questions:

  • Is tumor size an independent predictor of recurrence in PTC?
  • Does age affect prognosis?
  • What are optimal size cutoffs for prognosis risk stratification?
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The Study. Authors conducted a retrospective analysis of 574 patients with PTC who underwent surgical treatment with total or hemithyroidectomy. Patients were reevaluated every 6 months in the first 2 years post-treatment and every 12 months thereafter. Exploratory analyses were performed to identify optimal cutoff points for tumor size and age was examined through multivariate analysis to determine its effect on recurrence. 

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The Results. Patients with larger tumors were more likely to undergo total thyroidectomy and prophylactic central neck dissection, and receive radioactive iodine. There were 67 recurrences including 40 loco-regional, 7 with distant metastases, and 20 biochemical recurrences. On univariate analysis, tumor size was significantly associated with RFS.

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The Results (continued). Factors significantly associated with reduced RFS included age ≥55 years, male sex, microscopic ETE, macroscopic ETE, central and lateral neck nodal metastases, and extra-nodal extension. There was a 16% increased risk of disease recurrence with every 1-cm increase in size of primary tumor. No association was found between tumor size and RFS on multivariate analysis in patients aged <55 years and optimal cutoff for prediction of recurrence was ≥2 cm.

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Take Home Points:

  • Association between tumor size and RFS was weak in younger patients
  • Counsel patients aged >55 years following resection of PTC >2 cm in size that recurrence is possible
  • 52% increase in relative risk for PTC recurrence for every 1-cm increase in tumor size (assuming linear relationship in patients aged >55 years)
  • No incremental improvement in prognostic discrimination for tumor sizes other than 2 cm
  • Tumor size >2 cm confers a 5-fold increased risk for recurrence vs ≤2 cm
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