Modified Neck Dissection for Differentiated Thyroid Cancer

Abstract

Lymph node metastases occur early and often in papillary thyroid cancer, the most common differentiated cancer of the thyroid gland. Therefore, it is critical that surgeons involved in the management of patients with differentiated thyroid cancer (DTC) understand the biological progression of metastases to regional lymph nodes, and its implications, so as to perform anatomically appropriate and oncologically effective neck dissection, when indicated. Microscopic dissemination of papillary carcinoma occurs quite often: As many as 60% of patients harbor occult metastases in the clinically negative neck at the time of initial diagnosis of the primary tumor [1]. Clinically apparent or radiologically demonstrated metastases are present in no more than 10–15% of patients at initial presentation. Nevertheless, despite the large number of patients having micrometastases at initial presentation, only 4–5% of these patients progress to clinically apparent metastases, if they are observed after surgery of the primary tumor without elective regional node dissection. Their long-term survivorship and disease-specific mortality is not affected by this approach of observation of the clinically negative neck, with therapeutic neck dissection when these nodes become clinically apparent. It is also well known that the vast majority of patients—even those with nodal metastases at presentation—will be cured of disease with appropriate initial surgery, with minimal morbidity from their procedure. The surgeon who embarks on neck dissection for DTC must therefore be knowledgeable about the patterns of neck metastases from thyroid cancer and competent to resect all clinically significant disease—while identifying, protecting, and preserving all vital structures within the lateral neck.