title: Clinical significance of extrathyroid extension to the parathyroid gland of papillary thyroid carcinoma.
abstract: Extrathyroid extension is a prominent prognostic factor of papillary thyroid carcinoma (PTC). In the UICC TNM classification, minimal extension to the sternothyroid muscle and perithyroid soft tissue is classified as T3 and further massive extension is classified as T4, the highest T grade. However, there have been few studies on the clinical significance of extension to the parathyroid gland in a large case series. In this study, we investigated the prognosis of PTC with extension to the parathyroid gland in a series of 3208 patients who underwent initial surgery between 1997 and 2004. Of these patients, 51 (1.6%) showed extension to the parathyroid gland on pathological examination. Twenty-one of these patients had massive extrathyroid extension to other adjacent organs corresponding to pT4. The remaining 30 were enrolled in this study. The disease-free survival (DFS) of these 30 patients was significantly better (p<0.0001) than that of pT4 patients and did not differ from that of patients showing minimal extrathyroid extension without extension to the parathyroid gland (p = 0.6264). Furthermore, none of these 30 patients died of carcinoma. Taken together, it is appropriate that extension to the parathyroid gland of PTC is graded as minimal extrathyroid extension (pT3), but not massive extension (pT4). Since minimal extension did not affect patient prognosis in our series, it is suggested that extension to the parathyroid gland has little clinical significance in PTC.
authors.affiliation: Department of Surgery, Kuma Hospital, Kobe City, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ito
authors.forename: Kennichi
authors.initials: K
authors.lastname: Kakudo
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Hirokawa
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Fukushima
authors.forename: Chisato
authors.initials: C
authors.lastname: Tomoda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Inoue
authors.forename: Minoru
authors.initials: M
authors.lastname: Kihara
authors.forename: Takuya
authors.initials: T
authors.lastname: Higashiyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Uruno
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Takamura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Miya
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsuzuka
authors.forename: Akira
authors.initials: A
authors.lastname: Miyauchi
mesh_terms: D002291:Carcinoma, Papillary / Q000473:pathology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000473:pathology*; D010282:Parathyroid Neoplasms / Q000556:secondary*; D011379:Prognosis; D013964:Thyroid Neoplasms / Q000473:pathology*; D016896:Treatment Outcome