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widely invasive follicular thyroid carcinoma

Thursday 5 November 2015


A diameter greater than 4.0 cm, the presence of vascular invasion, the TNM stage III-IVA, and the high risk at AMES system risk stratification were independent factors significantly related to the presence of a WI-FTC.

The only independent predictor of recurrence and disease-free survival at 10-year follow-up was a tumor size greater than 4.0 cm.

More attention must be paid in the postoperative tumor re-staging of those patients with tumor size larger than 4.0 cm, which was the only parameter predicting recurrence and influencing disease-free survival.

WHO 2004

According to the World Health Organization (WHO) classification of thyroid tumors, FTC is defined by the presence of capsular and/or vascular invasion and by the absence of nuclear features typical of papillary thyroid carcinoma (PTC).

FTC is more likely to metastasize to distant organs rather than to regional lymph nodes because of its tendency to invade blood vessels thus resulting in hematogenous dissemination.

WHO classification also divides FTC into minimally invasive follicular thyroid carcinoma (MI-FTC) when limited capsular and/or vascular invasion is found and widely invasive follicular thyroid carcinoma (WI-FTC) in the case of widespread infiltration of thyroid tissue and/or vascular invasion.

Several authors usually reported a benign clinical course of MI-FTC owing to the low risk of tumor recurrence and distant dissemination. Conversely, other authors described that also MI-FTCs can give rise to distant metastases.

WI-FTC is deemed to have a worse prognosis than MI-FTC. The subset of prognostic factors associated with WI-FTC, however, has not been deeply investigated yet.

Moreover, the impact of vascular invasion on prognosis is still a matter to be debated as some authors further subdivided MI-FTCs into angioinvasive and non-angioinvasive tumors.

Age older than 45, sex, extra-thyroid invasion, greater tumor size, and the presence of distant metastasis at presentation are recognized risk factors for poorer prognosis of FTC.

Nevertheless, there is controversy concerning the prognostic significance of these risk factors, which could influence the treatment decision-making of patients with FTC [11].

As evidence on the biological behavior and clinical courses of MI-FTC and WI-FTC is still debatable, we carried out a retrospective cohort study in order to identify differences between MI and WI tumors and those prognostic parameters influencing late outcome such as recurrence and distant metastases.

Open references

- Follicular thyroid carcinoma: differences in clinical relevance between minimally invasive and widely invasive tumors. Podda M, Saba A, Porru F, Reccia I, Pisanu A. World J Surg Oncol. 2015 Jun 4;13:193. doi : 10.1186/s12957-015-0612-8 PMID: 26041024 (Free)