title: Incidence of second malignancies in prostate cancer patients treated with low-dose-rate brachytherapy and radical prostatectomy.
abstract: OBJECTIVE
  To compare the second malignancy incidence in prostate cancer patients treated with brachytherapy (BT) relative to radical prostatectomy (RP) and to compare both groups with the cancer incidence in the general population.
  
  
  METHODS
  From 1998 to 2010, 2418 patients were treated with Iodine 125 prostate BT monotherapy at the British Columbia Cancer Agency, and 4015 referred patients were treated with RP. Cancer incidence was compared with the age-matched general population using standardized incidence ratios (SIRs). Pelvic malignancies included invasive and noninvasive bladder cancer and rectal cancer. Cox multivariable analysis was performed with adjustment for covariates to determine whether treatment (RP vs BT) was associated with second malignancy risk.
  
  
  RESULTS
  The median age at BT was 66 years and at RP 62 years. The SIR comparing BT patients with the general population was 1.06 (95% confidence interval [CI] 0.91-1.22) for second malignancy and was 1.53 (95% CI 1.12-2.04) for pelvic malignancy. The SIR comparing RP patients with the general population was 1.11 (95% CI 0.98-1.25) for second malignancy and was 1.11 (95% CI 0.82-1.48) for pelvic malignancy. On multivariable analysis, older age (hazard ratio [HR] 1.05) and smoking (HR 1.65) were associated with increased second malignancy risk (P<.0001). Radical prostatectomy was not associated with a decreased second malignancy risk relative to BT (HR 0.90, P=.43), even when excluding patients who received postprostatectomy external beam radiation therapy (HR 1.13, P=.25). Older age (HR 1.09, P<.0001) and smoking (HR 2.17, P=.0009) were associated with increased pelvic malignancy risk. Radical prostatectomy was not associated with a decreased pelvic malignancy risk compared with BT (HR 0.57, P=.082), even when excluding postprostatectomy external beam radiation therapy patients (HR 0.87, P=.56).
  
  
  CONCLUSIONS
  After adjustment for covariates, BT patients did not have an increased second malignancy risk compared with RP patients. Further follow-up of this cohort is needed given the potential latency of radiation-induced malignancies.
authors.affiliation: Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Sarah Nicole
authors.initials: SN
authors.lastname: Hamilton
authors.affiliation: Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Scott
authors.initials: S
authors.lastname: Tyldesley
authors.affiliation: Department of Population Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Hamm
authors.affiliation: Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Wei Ning
authors.initials: WN
authors.lastname: Jiang
authors.affiliation: Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Mira
authors.initials: M
authors.lastname: Keyes
authors.affiliation: Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Pickles
authors.affiliation: Department of Medical Physics, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Vince
authors.initials: V
authors.lastname: Lapointe
authors.affiliation: Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Kahnamelli
authors.affiliation: Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: McKenzie
authors.affiliation: Department of Radiation Oncology, British Columbia Cancer Agency-Centre for the North, Prince George, British Columbia, Canada.
authors.forename: Stacy
authors.initials: S
authors.lastname: Miller
authors.affiliation: Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Department of Radiation Oncology, British Columbia Cancer Agency-Vancouver Centre, Vancouver, British Columbia, Canada. Electronic address: jmorris@bccancer.bc.ca.
authors.forename: W James
authors.initials: WJ
authors.lastname: Morris
mesh_terms: D000367:Age Factors; D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D001955:British Columbia / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D011468:Prostatectomy / Q000009:adverse effects* / Q000379:methods; D011471:Prostatic Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D012004:Rectal Neoplasms / Q000453:epidemiology; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects; D018709:Statistics, Nonparametric; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology
chemical_list: D007457:Iodine Radioisotopes