High dose-rate brachytherapy in the treatment of prostate cancer

Abstract

High dose-rate (HDR) brachytherapy involves delivery of a high dose of radiation to the cancer with great sparing of surrounding organs at risk. Prostate cancer is thought to be particularly sensitive to radiation delivered at high dose-rate or at high dose per fraction. The rapid delivery and high conformality of dose results in lower toxicity than that seen with low dose-rate (LDR) implants. HDR combined with external beam radiotherapy results in higher cancer control rate than external beam only, and should be offered to eligible high and intermediate risk patients. While a variety of dose and fractionations have been used, a single 15 Gy HDR combined with 40–50 Gy external beam radiotherapy results in a disease-free survival of over 90% for intermediate risk and 80% for high risk. HDR monotherapy in two or more fractions (e.g., 27 Gy in 2 fractions or 34.5 Gy in 3) is emerging as a viable alternative to LDR brachytherapy for low and low-intermediate risk patients, and has less toxicity. The role of single fraction monotherapy to a dose of 19–20 Gy is evolving, with some conflicting data to date. HDR should also be considered as a salvage approach for recurrent disease following previous external beam radiotherapy. A particular advantage of HDR in this setting is the ease of delivering focal treatments, which combined with modern imaging allows focal dose escalation with minimal toxicity. Trans-rectal ultrasound (TRUS) based planning is replacing CT-based planning as the technique of choice as it minimizes or eliminates the need to move the patient between insertion, planning and treatment delivery, thus ensuring high accuracy and reproducibility of treatment.

A novel 169Yb‐based dynamic‐shield intensity modulated brachytherapy delivery system for prostate cancer

“…20 IMBT also has potential for delivering focal therapy, where an inhomogeneous dose distribution is desired to specifically treat areas within the prostate where recurrent disease is present. 2 Delivery times for IMBT with an 18 Ci 169 Yb source are about twice as long as those for HDR BT with a 10 Ci 192 Ir source, but roughly equivalent to those obtained with a 2 Ci 60 Co source. 48 Nevertheless, IMBT treatments can be delivered in a reasonable timeframe (~20 mins) with the proposed system, relative to the total time (multiple hours) required for needle implantation, imaging, treatment planning, treatment delivery, and recovery.…”

“…Alternatively, IMBT could provide a method to escalate the monotherapy dose from 19 to 21 Gy or more without increasing the urethral dose, which could increase the effectiveness of brachytherapy as a monotherapy . IMBT also has potential for delivering focal therapy, where an inhomogeneous dose distribution is desired to specifically treat areas within the prostate where recurrent disease is present …”

“…High dose rate brachytherapy (HDR BT) for prostate cancer is an effective therapy delivered either as a monotherapy or as a boost in combination with external beam radiotherapy (EBRT) . The HDR BT boost is a recommended method of dose escalation for intermediate‐ and high‐risk prostate cancer .…”

“…High dose rate brachytherapy (HDR BT) for prostate cancer is an effective therapy delivered either as a monotherapy or as a boost in combination with external beam radiotherapy (EBRT). 1,2 The HDR BT boost is a recommended method of dose escalation for intermediate-and high-risk prostate cancer. 3,4 Several studies have reported a higher disease-free survival in patients treated with HDR BT combined with EBRT compared to those treated with EBRT alone.…”

“…[12][13][14] The low rate of toxicity for HDR BT monotherapy delivered in a single fraction of 19 Gy suggests that dose escalation may be beneficial, since local control rates are too low. 2 Further dose escalation to 21 Gy or more is currently limited by urethral dose constraints.…”