The potential of low-dose-rate brachytherapy with iodine-125 in the treatment of local recurrences of prostate cancer after primary high-dose-rate monotherapy

Abstract

Purpose: The incidence of local prostate cancer recurrences after monotherapy with high-dose-rate brachytherapy (HDR-BT) is low. However, a cumulated number of local recurrences during follow-up is naturally observed in highly specialized oncological centers. This retrospective study aimed to present the treatment of local recurrences after HDR-BT with low-dose-rate brachytherapy (LDR-BT).

Material and methods: Nine patients with low- and intermediate-risk prostate cancer with a median age of 71 years (range, 59-82 years) were diagnosed with local recurrences after previous monotherapy HDR-BT, 3 × 10.5 Gy (from 2010 to 2013). Median time to biochemical recurrence was 59 months (range, 21-80 months). All patients received 145 Gy with salvage LDR-BT (iodine-125). Gastrointestinal and urological toxicities were evaluated based on patients' records following CTCAE v. 4.0 and IPSS scales.

Results: The median follow-up after salvage treatment was 30 months (range, 17-63 months). Local recurrences (LR) were detected in two cases, and the actuarial 2-year local control was 88%. Biochemical failure was observed in four cases. Distant metastases (DM) were observed in 2 patients. In one patient, both LR and DM were diagnosed simultaneously. Four patients had no relapse of the disease, and a 2-year disease-free survival (DSF) was 58.3%. Before salvage treatment, median IPSS scores were 6.5 points (range, 1-23 points). At the first follow-up visit, after one month, the mean IPSS score was 20 points, and at the last follow-up visit, it was 8 points (range, 1-26 points). One patient had urinary retention after treatment. There was no significant change in IPSS scores before and after the treatment (p = 0.68). Two patients had grade 1 toxicity in the gastrointestinal tract.

Conclusions: Salvage LDR-BT for patients with prostate cancer previously treated with HDR-BT monotherapy is characterized by acceptable toxicity, and may result in local disease control.

Keywords: LDR brachytherapy; recurrence prostate cancer; salvage brachytherapy.

Fig. 1

Kaplan-Meier graph presenting the cumulative proportion of local control in patients after salvage low-doserate brachytherapy of recurrent prostate cancer.

Fig. 2

Kaplan-Meier graph presenting the cumulative proportion of disease-free survival in patients after salvage low-dose-rate brachytherapy of recurrent prostate cancer

Fig. 3

The graph presents IPSS scale of each patient. One patient was excluded because of chronic kidney disease and lack of urine production. Case 1 was not assessed before treatment. Cases number 2, 4, 5, 6, and 8 were not assessed on the first follow-up visit after treatment. However, any severe side effects were not mentioned during the visit in the medical history report. There was no difference between pre-salvage and last follow-up in IPSS scale (p = 0.91, Wilcoxon test)