Long-term safety and efficacy of a tamoxifen-based treatment strategy for idiopathic retroperitoneal fibrosis.

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.

CONCLUSION: Tamoxifen is a safe and viable therapeutic option in the treatment of iRPF.