title: Validity of 6(th) edition of UICC TNM classification system for medullary thyroid carcinoma: a proposal for intraoperative evaluation of T category.
abstract: Medullary thyroid carcinoma (MTC) accounts for 1.4% of all thyroid malignancies in Japan. Here, we studied the validity of a staging system evaluated preoperatively (Stage), intraoperatively (intra-Stage), and pathologically (pStage) based on the 6(th) and 7(th) UICC TNM classifications. One hundred and nineteen MTC patients who did not show distant metastasis at diagnosis and underwent locally curative surgery were enrolled in this study (average follow-up period: 173.4 months). Twenty-year clinical (not biochemical) disease-free survival (DFS) rates of Stage I, II, III, and IVA patients based on the 6(th) edition were 100, 88.2, 66.8, and 38.9%, respectively. DFS of Stage IVA patients was significantly poorer than that of Stage III patients (p = 0.03137). However, using the 7(th) edition, only 1 patient was classified with Stage III. Intra-Stage III patients based on the 6th edition showed a significantly poorer DFS (20-year DFS 50.0%) than intra-Stage II patients (92.9%) (p = 0.02668), and DFS of intra-Stage IVA patients (38.9%) tended to be poorer than that of intra-Stage III patients (p = 0.05439). Only one patient was classified with intra-Stage III using the 7(th) edition. In pStage, as many as 56 patients (47.1%) were classified with pStage IVA employing both editions. Taken together, Stage and intra-Stage were more useful to accurately discriminate high-risk patients than pStage, and their 6(th) editions were better than 7(th) editions. Although the number of patients was small, our data showed the possibility that intra-Stage in the 6(th) edition was the best staging system for MTC patients.
authors.affiliation: Department of Surgery, Kuma Hospital, Kobe 650-0011, Japan. ito01@kuma-h.or.jp
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ito
authors.forename: Minoru
authors.initials: M
authors.lastname: Kihara
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Hirokawa
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Takamura
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Miya
authors.forename: Akira
authors.initials: A
authors.lastname: Miyauchi
mesh_terms: D018276:Carcinoma, Medullary / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D018278:Carcinoma, Neuroendocrine; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007430:Intraoperative Care; D007564:Japan / Q000453:epidemiology; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology; D009367:Neoplasm Staging; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011379:Prognosis; D016019:Survival Analysis; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery