[The importance of lymph node dissection in medullary thyroid macrocarcinomas]

Medullary thyroid carcinoma (MTC) is often regarded as good medium-term forecast. The 5- and 10-years survival rates are, respectively, appraised at 78-85% and 70-78%. These rates take no care, however, of the fact that 50-56% of the patients keep a pathological calcitonine (CT) level giving evidence of an evolutive disease. The treatment is based on the total thyroidectomy and cervical lymphadectomy. This treatment remains often incomplete and the results of reintervention are disappointing.

About 48 patients, we wanted to demonstrate the importance of a complete lymph node dissection performed in the neck as soon as possible.

Between 1979 and 2000, 48 patients were treated for macroMTC (size >1 cm). The duration of follow-up was of 1-29 years (mean 9.3 years). The complete (central and lateral) neck dissection was initially made only in 22 cases. The selected criterion to assess the result was the normalization of the basal CT level.

The rate of node involvement was 66.6% if the complete lymphadectomies (n = 22), the secondary neck dissections (n = 15), the incomplete (n = 10) and not made lymphadectomies (n = 2) were gathered. In case of primary or secondary complete lymphadectomies, the rate of node involvement was 81%. The 22 primary complete lymphadectomies performed in 13 patients (59%) allowed to normalize the basal CT level and among 17 (77.2%) to decrease this rate over 90%. All the incomplete neck dissection failed in case of positive nodes.

The frequency of node involvement in macroMTC is about 80%. It does not have a preferential territory and the bilaterality is frequent (28-49%): that justifies a bilateral complete neck dissection. Initial surgical treatment seems essential in regard to the rate of normalization of basal CT level, which is, when a first complete lymphadectomy is done and in case of iterative surgery, respectively 59 and 26.6%. A complete lymphadectomy is still too rarely carried out: 22 times (45.8%) in our own experience and from 14 to 42% in the literature.