Prognostic markers in well differentiated papillary and follicular thyroid cancer (WDTC)

Abstract

Objectives: WDTC (papillary and follicular thyroid cancer) make up around 90% of all thyroid tumours. Overall, the prognosis in patients with WDTC is excellent. However, there are small cohorts of patients who experience a more aggressive form of disease which is often associated with certain poor prognostic factors. Identifying these patients at an early stage is imperative for guiding treatment decisions. With recent developments in this area we plan to discuss the current evidence surrounding prognostic markers.

Methods: The literature regarding prognostic factors in WDTC was reviewed using an electronic database Medline - Pubmed. Using the MeSH search engine specific prognostic factors including age, size, grade, lymph node involvement, distant metastasis, extension/invasion, ethnic background, radioactive iodine avidity, and thyroglobulin level and their association with WDTC were evaluated. A broader search of prognostic markers in thyroid cancer was also carried out to avoid missing other pertinent markers.

Results: Multiple clinical and pathologic variables have been shown to be poor prognostic factors in WDTC with statistical significance. Extensive extrathyroidal extension and age may be the most important factors when predicting clinical outcomes in WDTC, although the age threshold may be increased from 45 to 55 years in due course.

Conclusions: Management of WDTC has changed considerably over the last two years as reflected in evolving British and American Thyroid Guidelines. In all cases a combined multi-disciplinary approach, with consideration of the available guidelines and stratification systems should be utilised when planning an individualised treatment program to offer the best contemporary care to WDTC patients.

Keywords: Age; Differentiated thyroid cancer; Ethnic background; Extrathyroid extension; Grade; Invasion; Lymph node metastasis; Metastasis; Prognostic markers; Radioactive iodine avidity; Size; Stratification; Thyroglobulin.