title: Prognostic and staging implications of mandibular canal invasion in lower gingival squamous cell carcinoma.
abstract: A multi-institutional study was undertaken to determine whether mandibular canal (MC) invasion and mandibular medullary bone invasion are independent factors in lower gingival squamous cell carcinoma (SCC). A total of 345 patients with lower gingival SCC were retrospectively reviewed. Mandibular bone invasion was categorized into three types; no bone invasion; invasion through cortical bone (medullary); and MC invasion. The overall survival rate and factors affecting local, regional, and distant failures were assessed by Cox proportional hazards regression analysis and Kaplan-Meier estimates. Bone invasion was present in 201 (58%) patients, of whom 107 (31%) had medullary invasion and 94 (27%) had MC invasion. Using the International Union Against Cancer (UICC) staging system and American Joint Committee on Cancer (AJCC) system, 171 (50%) patients were classified as T4a. When the bone invasion criteria were excluded from the UICC/AJCC system definition, 152 T4a tumors were downstaged and reclassified to T1 in 12 (3%), to T2 in 98 (28%), and to T3 in 42 (12%). In Cox multivariate analysis, MC invasion was an independent predictor of overall survival but medullary bone invasion was not. Medullary bone invasion was an independent variable for distant control. The current T staging system has restricted prognostic utility. The authors recommend a modified T staging system, whereby tumors with MC invasion instead of medullary bone invasion are classified as T4a, and tumors are first classified as T1 to T3 based on size and then upstaged by one T classification in the presence of medullary invasion.
authors.affiliation: The First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Okura
authors.affiliation: Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Souichi
authors.initials: S
authors.lastname: Yanamoto
authors.affiliation: Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Umeda
authors.affiliation: Division of Surgery, Department of Oral and Maxillofacial Surgery, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Otsuru
authors.affiliation: Division of Surgery, Department of Oral and Maxillofacial Surgery, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Ota
authors.affiliation: Department of Dentistry and Oral Surgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kurita
authors.affiliation: Department of Dentistry and Oral Surgery, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kamata
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Medicine, Nara Medical University, Kashihara, Japan.
authors.forename: Tadaaki
authors.initials: T
authors.lastname: Kirita
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Medicine, Nara Medical University, Kashihara, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Yamakawa
authors.affiliation: Department of Oral and Maxillofacial Surgery, Keiyukai Sapporo Hospital, Sapporo, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Department of Oral and Maxillofacial Surgery, Keiyukai Sapporo Hospital, Sapporo, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Ueda
authors.affiliation: Department of Oral and Maxillofacial Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Takahide
authors.initials: T
authors.lastname: Komori
authors.affiliation: Department of Oral and Maxillofacial Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Hasegawa
authors.affiliation: The First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan.
authors.forename: Tomonao
authors.initials: T
authors.lastname: Aikawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000401:mortality* / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D005887:Gingival Neoplasms / Q000175:diagnosis* / Q000401:mortality*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008334:Mandible / Q000473:pathology*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis
keywords: Bone invasion; TNM staging; head and neck cancer; oral cancer; overall survival; prognosis; squamous cell carcinoma