title: Skeletal Metastasis of Unknown Primary Origin at the Initial Visit: A Retrospective Analysis of 286 Cases.
abstract: BACKGROUND
  Skeletal metastasis is a common metastatic event for several carcinomas, and the treatment for skeletal metastasis of unknown primary (SMUP) are a critical issue in cancer therapy. Making a diagnosis of the primary site is the most crucial step in the treatment of SMUP; however, the procedures are sometimes difficult and time-consuming, and the primary site often remains unknown. Therefore, to establish optimal diagnostic strategies and elucidate the overall survival rates of SMUP, we conducted this retrospective study.
  
  
  METHODS
  We retrospectively analyzed the clinical data for 286 SMUP cases from a total of 2,641 patients with skeletal metastases who were treated between 2002 and 2014 at our initiations.
  
  
  RESULTS
  The primary sites were identified in 254/286 patients (88.8%), while 32 (11.2%) primary sites were not detected by our diagnostic strategies. Lung cancer was identified in 72 (25.2%) cases, and was the most frequently observed primary lesion. The median survival time of the SMUP patients was 20.0 months, while the median survival times of solitary bone metastasis cases and multi-bone metastasis cases were 39.0 months and 16.0 months, respectively. The median survival times of prostate cancer cases was over 120 months, that of patients with primary lung cancers was 9.0 months and the median survival time of cases who were finally diagnosed with an unknown primary was 11.0 months.
  
  
  CONCLUSIONS
  We believe that our study would contribute to establishing an optimal strategy for diagnosing the primary site in SMUP patients, and our data provide definite indications for the survival times for different SMUP situations.
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan; Department of Orthopaedic Surgery, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Takagi
authors.affiliation: Department of Orthopaedic Surgery, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Katagiri
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Yongji
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suehara
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kubota
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Akaike
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Midori
authors.initials: M
authors.lastname: Ishii
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Mukaihara
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Taketo
authors.initials: T
authors.lastname: Okubo
authors.affiliation: Department of Orthopaedic Surgery, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Murata
authors.affiliation: Department of Orthopaedic Surgery, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Saito
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D001706:Biopsy; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000556:secondary* / Q000628:therapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D014408:Biomarkers, Tumor