title: Prevalence and risk factors of bone metastasis and skeletal related events in patients with primary breast cancer in Japan.
abstract: BACKGROUND
  Bone metastasis (BM) is important for studying systemic spread of breast cancer. It often causes skeletal-related events (SREs) that worsen quality of life. We investigated the prevalence and risk factors for BM and SRE using a dataset from the Breast Oncology Research Network (BORN) in Japan.
  
  
  METHODS
  We collected data on primary breast cancer patients with node-positive or node-negative disease at intermediate to high risk of recurrence. The risk factors affecting the BM-free rate, SRE-free rate and overall survival were analyzed by using the Cox proportional hazard model.
  
  
  RESULTS
  Data of 1,779 patients who were diagnosed with breast cancer during 2003-2005 were collected from the BORN and 1,708 cases were used for analysis. The median follow-up duration was 5.71 years. BM developed in 193 cases (11.3 %) and the BM-free rate at 5 years was 89.2 %. The annual hazard ratio of BM development differs remarkably according to the tumor subtype. SREs occurred in 133 (68.9 %) out of 193 patients and the SRE-free rate at 5 years was 92.6 %. In the multivariate analysis, clinical stage (P < 0.0001), number of lymph node (LN) metastases (P = 0.0029), tumor subtype (P = 0.034) and progesterone receptor status (P = 0.038) were independently significant risk factors for BM-free rate, but only clinical stage (P < 0.0001) and number of LN metastases (P = 0.0004) significantly correlated with SRE-free rate.
  
  
  CONCLUSIONS
  This retrospective study clarifies the prevalence and risk factors for BM and SRE in Japanese breast cancer patients. Our results show the importance of considering subtype in the care of BM and SRE.
authors.affiliation: Department of Breast Surgery, Kure Medical Center/Chugoku Cancer Center, Kure, Hiroshima, 737-0023, Japan, yamashiro.bcs@gmail.com.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Yamashiro
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takada
authors.forename: Eiji
authors.initials: E
authors.lastname: Nakatani
authors.forename: Shiro
authors.initials: S
authors.lastname: Imai
authors.forename: Akira
authors.initials: A
authors.lastname: Yamauchi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Tsuyuki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Matsutani
authors.forename: Shingo
authors.initials: S
authors.lastname: Sakata
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Wada
authors.forename: Ryuji
authors.initials: R
authors.lastname: Okamura
authors.forename: Tomika
authors.initials: T
authors.lastname: Harada
authors.forename: Fumie
authors.initials: F
authors.lastname: Tanaka
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Moriguchi
authors.forename: Hironori
authors.initials: H
authors.lastname: Kato
authors.forename: Shunichi
authors.initials: S
authors.lastname: Higashide
authors.forename: Norimichi
authors.initials: N
authors.lastname: Kan
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoshibayashi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Suwa
authors.forename: Takashi
authors.initials: T
authors.lastname: Okino
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakayama
authors.forename: You
authors.initials: Y
authors.lastname: Ichinose
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamagami
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Inamoto
authors.forename: Masakazu
authors.initials: M
authors.lastname: Toi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000556:secondary; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy*; D005260:Female; D006801:Humans; D007564:Japan; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy*; D011788:Quality of Life; D012307:Risk Factors
chemical_list: D050071:Bone Density Conservation Agents