PSA bounce after ¹²⁵I-brachytherapy for prostate cancer as a favorable prognosticator

Permanent low-dose-rate brachytherapy (BT) with iodine 125 is an established curative treatment for localized prostate cancer. After treatment, prostate-specific antigen (PSA) kinetics may show a transient rise (PSA bounce). Our aim was to investigate the association of PSA bounce with biochemical control.

Patients treated with BT in Switzerland were registered in a prospective database. Only patients with a follow-up of at least 2 years were included in our analysis. Clinical follow-up and PSA measurements were assessed after 1.5, 3, 6, and 12 months, and annually thereafter. If PSA increased, additional follow-up visits were scheduled. Cases of PSA bounce were defined as a rise of at least 0.2 ng/ml above the initial PSA nadir with a subsequent decline to or below the initial nadir without treatment. Biochemical failure was defined as a rise to nadir + 2 ng/ml.

Between March 2001 and November 2010, 713 patients with prostate cancer undergoing BT with at least 2 years of follow-up were registered. Median follow-up time was 41 months. Biochemical failure occurred in 28 patients (3.9 %). PSA bounce occurred in 173 (24.3 %) patients; only three (1.7 %) patients with PSA bounce developed biochemical failure, in contrast to 25 (4.6 %) patients without previous bounce (p < 0.05). The median time to bounce was 12 months, the median time to biochemical failure was 30 months. The median bounce increase was 0.78 ng/ml. Twenty-eight patients with bounce (16.5 %) had a transient PSA rise of + 2 ng/ml above the nadir.

In most cases, an early increase in PSA after BT indicates PSA bounce and is associated with a lower risk of biochemical failure.