Primary surgery for differentiated thyroid cancer in the new millennium

Differentiated thyroid cancers (DTC) are malignancies of follicular cell derivation. Histopathologically and oncologically, DTC fall into two broad tumor categories: papillary (PTC) and follicular thyroid cancer (FTC). These major tumor categories, based on clinical manifestation and biological behavior, are further subdivided into low-risk [papillary microcarcinoma (mPTC); minimally invasive follicular cancer (MIFTC)] and high-risk DTC [PTC>1 cm or metastatic; MIFTC with histopathological angioinvasion; widely invasive FTC (WIFTC)]. Recently, a surgical approach has been adopted that differentiates between low-risk and high-risk DTC. The rationale behind this new concept is to better balance oncologic risk (high vs low) with the surgical morbidity attendant to the procedure (recurrent laryngeal nerve palsy and hypoparathyroidism). This surgical risk is larger with routine total thyroidectomy (TT) and central node dissection (CND) than with less than TT or TT without CND.Whereas TT with CND remains the treatment of choice for high-risk DTC with metastases, the extent of thyroid resection and lymph node dissection can be reduced in low-risk PTC and FTC without demonstrable loss of oncological benefit. In the new millennium, the surgical approach to DTC, especially low-risk PTC and FTC, has undergone considerable change, resulting in less extensive procedures. This risk-adapted strategy relies not only on the skillful histopathologic detection of multifocality in PTC and vascular invasion in MIFTC, but likewise necessitates diligent follow-up to spot and adequately treat local recurrences and distant metastases as they become clinically apparent.