title: Second primary malignancy risk among patients with gastric cancer: a nationwide population-based study in Taiwan.
abstract: BACKGROUND
  Several studies have reported an increase in second primary malignancies (SPMs) among gastric cancer patients.
  
  
  METHODS
  Patients who were newly diagnosed with gastric cancer between 1997 and 2011 were recruited from the Taiwan National Health Insurance database. Those who had antecedent malignancies or gastrointestinal stromal tumor were excluded. Standardized incidence ratios (SIRs) of SPMs were calculated. Risk factors for cancer development were analyzed by Cox proportional hazards models. Effects of treatments for gastric cancer were treated as time-dependent variables.
  
  
  RESULTS
  During the 15-year study period, 47,729 gastric cancer patients were recruited. Overall, 2,110 SPMs developed during a total follow-up of 137,798 person-years. The SIR for all cancers was 1.46. The SIRs for specific follow-up periods were 1.43, 1.41, and 1.21 at >10 years, 5-10 years, and 1-5 years, respectively. After excluding SPMs that developed within 1 year, significantly higher SIRs were seen for cancers of the head and neck (1.34), esophagus (2.16), colon and rectum (1.37), bones and soft tissues (1.95), ovaries (2.89), bladder (1.47), or kidneys (1.44), as well as non-Hodgkin's lymphoma (5.56). Multivariate analysis showed that age ≥70 years [hazard ratio (HR) 1.19], being male (HR 1.37), diabetes mellitus (HR 1.30), chronic obstructive pulmonary disease (HR 1.17), and liver cirrhosis (HR 1.94) were independent risk factors. Radiotherapy (HR 1.24) and chemotherapy (HR 1.87) were independent risk factors, but surgery (HR 0.67) was not.
  
  
  CONCLUSIONS
  Patients with gastric cancer are at increased risk of developing SPM. Close surveillance of patients with risk factors over a longer period should be considered.
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: San-Chi
authors.initials: SC
authors.lastname: Chen
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.|School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chia-Jen
authors.initials: CJ
authors.lastname: Liu
authors.affiliation: Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.|School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Hu
authors.affiliation: Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Chiu-Mei
authors.initials: CM
authors.lastname: Yeh
authors.affiliation: Department of Psychiatry, Kaohsiung Veterans General Veterans Hospital, Kaohsiung, Taiwan.
authors.forename: Li-Yu
authors.initials: LY
authors.lastname: Hu
authors.affiliation: School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Endoscopy Center of Diagnosis and Treatment, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Yen-Po
authors.initials: YP
authors.lastname: Wang
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Hung
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Cheng-Hwai
authors.initials: CH
authors.lastname: Tzeng
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Division of Transfusion Medicine, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Tzeon-Jye
authors.initials: TJ
authors.lastname: Chiou
authors.affiliation: School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Tzeng-Ji
authors.initials: TJ
authors.lastname: Chen
authors.affiliation: Institute of Public Health, National Yang-Ming University, Taipei, Taiwan. cjteng.tw@gmail.com.|School of Medicine, National Yang-Ming University, Taipei, Taiwan. cjteng.tw@gmail.com.|Division of Hematology and Oncology, Department of Medicine, Far Eastern Memorial Hospital, No. 21, Sec. 2, Nanya S. Rd., Banciao Dist, 22060, New Taipei City, Taiwan. cjteng.tw@gmail.com.
authors.forename: Chung-Jen
authors.initials: CJ
authors.lastname: Teng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D005743:Gastrectomy / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000628:therapy; D016016:Proportional Hazards Models; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000628:therapy; D013624:Taiwan / Q000453:epidemiology
keywords: Gastric cancer; Population-based study; Second primary malignancy