Pattern of regional metastases and prognostic factors in differentiated thyroid carcinoma
Metastatizzazione linfonodale e fattori prognostici nel carcinoma differenziato della tiroide
G. Spriano, P. Ruscito, R. Pellini, M. Appetecchia1, R. Roselli
Department of Otolaryngology, Head & Neck Surgery, 1 Endocrinology Unit, Regina Elena National Cancer Institute, Rome, Italy
Summary
The meaning of nodal metastases in well-differentiated thyroid carcinoma is controversial. The Authors analyse the impact of lymphatic spread reviewing 1503 cases of well-differentiated thyroid carcinoma treated at the National Cancer Institute of Rome between 1988 and 2005, in order to detect signifi cant prognostic factors through multivariate analysis. Overall, 462 cases of locally advanced well-differentiated thyroid carcinoma, were considered. A multivariate analysis of a subgroup, comprising 97 N+ consecutive cases of well-differentiated thyroid carcinoma, previously untreated, was performed to study prognostic factors for local (N+) and distant (M+) metastasis in welldifferentiated thyroid carcinoma. Of the 97 cases, 88 were submitted to surgery for a large well-differentiated thyroid carcinoma, 9 for occult differentiated thyroid carcinoma. After surgery, 12 patients were lost to follow-up, 8 resulted pathologically negative, therefore only 77 cases of pN1 well-differentiated thyroid carcinoma were studied. Considering all cases of well-differentiated thyroid carcinoma, 10- year-overall survival was 58.7% for locally advanced well-differentiated thyroid carcinoma, compared to 94.8% in low stage cases. Neck dissection, margin infi ltration and extra-capsular spread were signifi cant prognostic factors. The Authors present a retrospective study of 77 patients with primary differentiated thyroid carcinoma, submitted to thyroidectomy and neck dissection aimed at analysing distribution of nodal metastases according to Robbins’ levels classifi cation and defi ning their prognostic value. All N1b cases, retrospectively reviewed (n. 77), presented clinical and histological evidence of neck nodes metastases from differentiated thyroid carcinoma; histological reports indicated tumour localisation and topographical distribution of metastases; papillary carcinoma was the most common type (72 cases), followed by follicular carcinoma (5 cases). Surgical treatment always comprised total thyroidectomy and 6th level dissection. Overall 52 cases were submitted to monolateral neck dissection, 25 to bilateral neck dissection. Treatment of the lateral neck was postero-lateral neck dissection (n. 53), selective lateral neck dissection (n. 20), modifi ed radical and radical (n. 29). Cervical level IV was the most frequently involved (52%), extra-capsular spread of metastases was identifi ed in 22% of the cases. Statistically signifi cant prognostic factors for distant metastases and recurrence on the neck were follicular carcinoma (p < 0.01) and extra-capsular spread (p < 0.001). Age, pT, sex, number of positive nodal metastases, T-extension and the number of nodal positive levels were not signifi cant. In the Authors’ experience, histological grade of differentiation, wide tumour excision and neck dissection, in cases of N1b well-differentiated thyroid carcinoma, without residual disease (R1, R2), in the central and lateral neck, are determinant prognostic factors. Extracapsular spread in particular, was found to be a highly predictive factor either of distant metastasis or regional recurrence.
Riassunto
Il signifi cato delle metastasi linfonodali nel carcinoma differenziato della tiroide è tuttora controverso. Gli Autori analizzano il valore prognostico della metastatizzazione linfonodale, mediante lo studio retrospettivo di 1503 casi di carcinoma differenziato della tiroide, trattati presso l’Istituto Nazionale Tumori “Regina Elena” di Roma, nel periodo compreso tra il 1988 ed il 2005. In particolare è stato estrapolato un sottogruppo di 77 casi di carcinomi sottoposti a tiroidectomia totale, svuotamento linfonodale ricorrenziale (6° livello) e svuotamento linfonodale laterocervicale per metastasi linfonodali (pN1). Quest’ultimo è consistito in uno svuotamento selettivo postero-laterale (livv. 2-5) in 53 casi, selettivo laterale (livv. 2-4) in 20 casi, radicale modifi cato o radicale in 29 casi. Il livello linfonodale maggiormente interessato è risultato essere il 4° (52%). La metastatizzazione linfonodale extracapsulare è stata documentata nel 22% dei casi. Sono stati analizzati mediante analisi multivariata i seguenti parametri: età, sesso, pT, istotipo, il numero di linfonodi, il/i livello/i cervicali coinvolti, secondo la classifi cazione di Robbins, la diffusione metastatica extra-capsulare dei linfonodi. Sono risultati statisticamente signifi cativi per la metastatizzazione a distanza e la recidiva linfonodale la variante follicolare (p < 0,01) ed il coinvolgimento extracapsulare delle metastasi linfonodali (p < 0,001). Non sono per contro risultati signifi cativi l’età, il sesso, il numero di linfonodi metastatici, le dimensioni di T. Nell’esperienza degli Autori l’extracapsularità linfonodale costituisce un importante parametro clinico predittivo del comportamento biologico di un carcinoma tiroideo differenziato e localmente avanzato. Un corretto approccio chirurgico del tumore primitivo e delle stazioni linfonodali cervicali laterali e del compartimento mediano è allo stato attuale determinante ai fi ni dell’esito oncologico della malattia.