title: Clinical characteristics of multiple primary carcinomas of the oral cavity.
abstract: OBJECTIVE
  This study aimed to clarify the clinical characteristics of multiple primary carcinomas of the oral cavity.
  
  
  METHODS
  We retrospectively reviewed the cases of 1015 patients who were treated during follow up for oral cancer at Tokyo Medical and Dental University between March 2001 and December 2012. We compared the clinical characteristics of 961 patients who developed single primary oral squamous cell carcinoma (SCC) during follow up and 54 patients who subsequently developed multiple primary carcinomas in the oral cavity.
  
  
  RESULTS
  Mean age at first diagnosis was significantly higher in patients with multiple primary carcinomas than single primary carcinoma. Multiple primary carcinomas showed a female predilection, were most prevalent in the gingiva, and tended to show earlier tumor and nodal stages than single primary carcinoma. The local recurrence rate was higher for multiple primary carcinomas than single primary carcinoma, and it increased with the number of multiple primary occurrences. The disease-specific survival rate at 10 years for patients with single primary carcinoma was 85.3% and that for patients with multiple primary carcinomas was 79.6%. The cumulative incidence rate for metachronous second multiple primary carcinomas after the onset of first carcinoma at 10 years was 8.0%. The recurrence of multiple primary carcinomas did not decrease the survival rate.
  
  
  CONCLUSIONS
  Differences were found in the clinical characteristics between patients with single oral SCC and those with multiple primary oral carcinomas. Early diagnosis and treatment as well as close long-term follow up are needed for patients with multiple primary oral carcinomas.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Mochizuki
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: hiro-harada.osur@tmd.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Harada
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Ikuta
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimamoto
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tomioka
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Kae
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hirai
authors.affiliation: Department of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Omura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000473:pathology*; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D012907:Smoking
keywords: Multiple primary carcinomas; Oral cavity; Squamous cell carcinoma; Survival rate; The cumulative incidence rate