Sentinel lymph node biopsy in differentiated thyroid carcinoma in decision for selective modified lateral neck dissection

Uvod: Diferentovani tiroidni karcinomi (DTK) čine do 90% svih tiroidnih maligniteta i najčešći su primarni maligniteti endokrinog sistema. Njihova učestalost je u značajnom porastu u poslednje tri decenije, a posebno malih papilarnih tiroidnih karcinoma (PTK). U vreme dijagnoze učestalost okultnih limfonodalnih metastaza (LNM) iznosi od 80 do 90%. U poslednjih 15 godina, LNM su prepoznate kao loš prognostički faktor za pojavu lokoregionalnog relapsa bolesti (LRR) i kancer-specifičnog preživljavanja. Postoji generalna saglasnost da su disekcije vrata indikovane kod klinički suspektnih LNM. Predmet aktuelnih kontroverzi predstavlja hirurški postupak sa okultnim LNM koje preoperativnom dijagnostikom ostaju neprepoznate (cN0). Opseg operacije na limfnim nodusima kreće se od teorije „sačekati i videti” takozvane „zapadne škole” argumentovane ulogom primene ablativne terapije J131 i učestalošću peroperativnih komplikacija (povrede povratnog laringealnog nerva i hipoparatireoidizma) posebno kod manje iskusnih timova, do obostranih profilaktičkih disekcija centralne i lateralne regije vrata takozvane „japanske škole” zbog ograničene upotrebe radioaktivnog joda u terapijske svrhe kao i značajno manjeg operativnog morbiditeta ukoliko se disekcija uradi u primarnom aktu. Uprkos visokoj prevalenci okultnih LNM, postojeće kontroverze u dijagnostici, dugoročnom prognostičkom značaju i opsegu operacija na limfnim nodusima, motivisale su neke autore da koncept provere stražarskih limfnih nodusa (SLN) primene kod pacijenata sa DTK, imajući u vidu odlične rezultate kod karcinoma dojke i melanoma kože. Cilj: Cilj ovog istraživanja je da se ispita da li je intraoperativno markiranje metilen plavim i provera stražarskih limfnih nodusa pouzdana metoda u detekciji limfonodalnih metastaza u lateralnoj regiji vrata prilikom donošenja odluke za selektivnu modifikovanu lateralnu disekciju vrata pacijenata sa diferentovanim tiroidnim karcinomom sa klinički nezahvaćenim limfnim nodusima...Introduction: Differentiated thyroid carcinoma (DTC) account up to 90% of all thyroid malignacies, and represents the most common malignant tumors of endocrine system. The incidence of papillary thyroid carcinoma (PTC), especially small tumors is rapidly increasing during past three decades. At the time of diagnosis, the incidence of occult lymph node metastases (LNM) ranges from 80 to 90%. During the last 15 years, LNM were recognized as bad prognostic factor for both local-regional relapse (LRR) and cancer specific survival. There is general agreement that neck dissections are indicated in cases of clinically apparent LNM. The subject of the current controversy is the surgical treatment of occult LNM that remain unrecognized on preoperative diagnosis (cN0). The extent of operations of the lymph nodes ranges from "wait and see" socalled "Western school" principle substantiated the role of applying ablative I131therapy and frequency peroperative complications (recurrent laryngeal nerve injury and hypoparathyroidism), especially for less experienced teams to mutual prophylactic dissection of the central and lateral compartments so-called "Japanese school " due to the limited use of radioactive iodine therapy and significantly lower operating morbidity if dissetion was done during primary operation. Despite high prevalence of occult LNM, existing controversies regarding diagnosis, longterm prognostic impact and extent of lymph node surgery, motivated some authors to apply consept of sentinel lymph node biopsy (SLNb) in DTC, taking into account excellent results of SLN concept in breast cancer and skin melanoma. Aim: Aim of this study was to investigate is intraoperative mapping with methylen blue dye and sentinel lymph node biopsy accurate method in detection of LNM in lateral neck compartment and may help in decision for selective modified lateral neck dissection in patients with DTC with clinically negative lymph nodes (cN0)..