Role of Isotope Selection in Long-term Outcomes in Patients With Intermediate-risk Prostate Cancer Treated With a Combination of External Beam Radiotherapy and Low-dose-rate Interstitial Brachytherapy

Abstract

OBJECTIVE To examine the rates of long-term biochemical recurrence-free survival (BRFS) with respect to isotope in intermediate-risk prostate cancer treated with external beam radiotherapy (EBRT) and brachytherapy. METHODS A total of 242 consecutive patients with intermediate-risk prostate cancer were treated with iodine-125 (125I) or palladium-103 (103Pd) implants after EBRT (range 45.0–50.4 Gy) from 1996 to 2002. Of the 242 patients, 119 (49.2%) were treated with 125I and 123 (50.8%) with 103Pd. Multivariate Cox regression analysis was used to analyze BRFS, defined according to the Phoenix definition (prostate-specific antigen nadir plus 2 ng/mL) with respect to Gleason score, stage, pretreatment prostate-specific antigen level, and source selection. Late genitourinary/gastrointestinal toxicities were assessed using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale. RESULTS At a median follow-up of 10 years, the BRFS rate was 77.3%. A statistically significant difference was found in the 10-year BRFS rate between the 125I- and 103Pd-treated groups (82.7% and 70.6%, respectively; P = .001). The addition of hormonal therapy did not improve the 10-year BRFS rate (77.6%) compared with RT alone (77.1%; P = .22). However, a statistically significant difference in the BRFS rate was found with the addition of hormonal therapy to 103Pd, improving the 10-year BRFS rate for (73.8%) compared with 103Pd alone (69.1%; P = .008). On multivariate analysis, isotope type (103Pd vs 125I), pretreatment prostate-specific antigen level > 10 ng/mL, and greater tumor stage increased the risk of recurrence by 2.6-fold (P = .007), 5.9-fold (P < .0001), and 1.7-fold (P = .14), respectively. CONCLUSION 125I renders a superior rate of BRFS compared with 103Pd when used with EBRT. Hormonal therapy does not provide additional benefit in patients with intermediate-risk prostate cancer treated with a combination of EBRT and brachytherapy, except for the addition of hormonal therapy to 103Pd.

CT-guided permanent 125I seed interstitial brachytherapy for recurrent retroperitoneal lymph node metastases after external beam radiotherapy

“…Iodine-125, 103 Pd, and 131 Cs have a half-life of approximately 60 days, 17 days, and 9.7 days, respectively. With a longer half-life, 125 I is better for slow-growing tumors (13).…”

Ablative Focused Ultrasound Synergistically Enhances Thermally Triggered Chemotherapy for Prostate Cancer in Vitro

“…Multiple shots of HIFU are required to cover the entire tumor volume, which dramatically increases the procedure time and a risk of complications due to HIFU beam misalignment. , This necessitates a combination therapy that can affect large areas of the prostate with relatively low intensities and fewer shots of ablative HIFU. It should be noted that combination treatments with multiple types of therapies, e.g., radiation therapy, brachytherapy, and hormonal therapy, have proven to be an effective choice to reduce cancer recurrence …”

“…It should be noted that combination treatments with multiple types of therapies, e.g., radiation therapy, brachytherapy, and hormonal therapy, have proven to be an effective choice to reduce cancer recurrence. 23 Chemotherapy is a last-hope treatment for patients with metastatic cancer because it can destroy cancer cells spread beyond the organ of origin. Recent studies also show that the survival rate of high-risk localized prostate cancer patients originally treated with radiation therapy and hormonal therapy increases after adjuvant chemotherapy.…”