title: Long-term safety and efficacy of a tamoxifen-based treatment strategy for idiopathic retroperitoneal fibrosis.
abstract: BACKGROUND
  Tamoxifen may be a viable treatment option for idiopathic retroperitoneal fibrosis (iRPF) but data are limited and its long-term safety and efficacy is unclear. We describe the long-term course and outcomes in a large group of patients with iRPF treated with tamoxifen monotherapy.
  
  
  METHODS
  This is a single-center prospective, observational study of 55 patients with iRPF treated with tamoxifen for 2years from April 1998 through April 2011. Measurements included clinical improvement, laboratory parameters and follow-up computed tomographic (CT) scanning. Treatment success was the composite endpoint of clinical improvement, mass regression and definite resolution of ureteral obstruction.
  
  
  RESULTS
  Forty-seven (85%) patients reported substantial resolution of symptoms after median treatment duration of 3.0weeks (IQR 1.4-4.8weeks). Repeated CT scanning showed mass regression in 39 (71%) patients at 4months and 47 (85%) patients at 8months of follow-up, respectively. Nineteen (34.5%) patients did not meet the composite endpoint of treatment success, 56% of whom responded satisfactorily to second-line immunosuppressive treatment. Recurrence-free survival in patients with treatment success after post-treatment follow-up of 21months (IQR 9.0-35.0months) was 68%. Tamoxifen was well tolerated. Pulmonary embolism occurred in 2 patients receiving tamoxifen and in one patient receiving second-line treatment.
  
  
  CONCLUSIONS
  Tamoxifen is a safe and viable therapeutic option in the treatment of iRPF.
authors.affiliation: Department of Internal Medicine, Albert Schweitzer Hospital, Dordrecht, The Netherlands. e.f.h.vanbommel@asz.nl
authors.forename: E F H
authors.initials: EF
authors.lastname: van Bommel
authors.forename: L G
authors.initials: LG
authors.lastname: Pelkmans
authors.forename: H
authors.initials: H
authors.lastname: van Damme
authors.forename: T R
authors.initials: TR
authors.lastname: Hendriksz
mesh_terms: D000368:Aged; D004965:Estrogen Antagonists / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012185:Retroperitoneal Fibrosis / Q000000981:diagnostic imaging / Q000188:drug therapy*; D013629:Tamoxifen / Q000008:administration & dosage* / Q000009:adverse effects*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D004965:Estrogen Antagonists; D013629:Tamoxifen