Localized prostate cancer with intermediate- or high-risk features treated with combined external beam radiotherapy and iodine-125 seed brachytherapy

Abstract 

Objective

The aim of the study is to compare the results of the combined external beam radiotherapy (EBRT) with iodine-125 seed brachytherapy vs. brachytherapy alone for prostate cancer treatment in patients with intermediate and high risk of disease recurrence.

Methods and Materials

Ninety-six patients were treated from January 1998 to December 2006. Twenty-four patients received combined treatment and 72 patients received brachytherapy alone. Patients were classified into intermediate or high risk of recurrence according to the D’Amico’s classification. The prescribed dose for brachytherapy was 145Gy as monotherapy and 110Gy for combined treatment. The dose of EBRT was 45Gy over 5 weeks, with 1.8Gy daily fractions. Results were analyzed based on Phoenix definition of biochemical recurrence, that is, nadir plus 2ng/mL.

Results

Biochemical control was achieved by 96% (23 of 24) of patients receiving combined treatment and by 72% (52 of 72) in the group treated by brachytherapy alone (p<0.015). The addition of EBRT resulted in a 94% biochemical disease-free survival at 5 years; and in brachytherapy alone group, the rate was 54% (p<0.011). Mean followup was 96 months (24–132 months; confidence interval 95%: 90–102).

Conclusion

This study shows that in patients with localized prostate cancer, with intermediate and high risk of biochemical recurrence, the addition of EBRT can confer a significant biochemical control advantage when added to brachytherapy.

Keywords: Brachytherapy, Iodine radioisotopes, Prostate-specific antigen, Prostatic neoplasms, Radiotherapy, Recurrence