Dosimetric Coverage of the Prostate, Normal Tissue Sparing, and Acute Toxicity with High-Dose-Rate Brachytherapy for Large Prostate Volumes

Abstract

PurposeTo evaluate dosimetric coverage of the prostate, normal tissue sparing, and acute toxicity with HDR brachytherapy for large prostate volumes.Materials and MethodsOne hundred and two prostate cancer patients with prostate volumes >50 mL (range: 5-29 mL) were treated with high-dose-rate (HDR) brachytherapy ± intensity modulated radiation therapy (IMRT) to 4,500 cGy in 25 daily fractions between 2009 and 2013. HDR brachytherapy monotherapy doses consisted of two 1,350-1,400 cGy fractions separated by 2-3 weeks, and HDR brachytherapy boost doses consisted of two 950-1,150 cGy fractions separated by 4 weeks. Twelve of 32 (38%) unfavorable intermediate risk, high risk, and very high risk patients received androgen deprivation therapy. Acute toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4.ResultsMedian follow-up was 14 months. Dosimetric goals were achieved in over 90% of cases. Three of 102 (3%) patients developed Grade 2 acute proctitis. No variables were significantly associated with Grade 2 acute proctitis. Seventeen of 102 (17%) patients developed Grade 2 acute urinary retention. American Urological Association (AUA) symptom score was the only variable significantly associated with Grade 2 acute urinary retention (p=0.04). There was no ≥ Grade 3 acute toxicity.ConclusionsDosimetric coverage of the prostate and normal tissue sparing were adequate in patients with prostate volumes >50 mL. Higher pre-treatment AUA symptom scores increased the relative risk of Grade 2 acute urinary retention. However, the overall incidence of acute toxicity was acceptable in patients with large prostate volumes.

What pelvic radiation disease symptoms are experienced by patients receiving external beam radiotherapy and a high-dose-rate brachytherapy boost for prostate cancer?

“…This study provides a comprehensive analysis of patients’ pelvic radiation disease symptoms following EBRT plus HDR brachytherapy for prostate cancer. Consistent with previous studies, we found that bowel side-effects were infrequent [ 14 , 15 ]. Furthermore, we found that patients generally recovered from treatment over time with fewer bowel symptoms reported at 12 months.…”

“…Using the EORTC proctitis module offered the advantage of capturing the range of pelvic symptoms patients experienced following EBRT and HDR brachytherapy. Other studies using clinician-reported instruments did not describe the range of symptoms we explored or the incidence of symptoms aside from rectal bleeding [ 14 , 15 ]. The most commonly experienced symptoms included feeling of bloating and passing excessive wind.…”

“…Yang et al [ 14 ] reported that 3% of patients experienced acute pelvic side effects after EBRT and/or HDR brachytherapy using the Common Terminology Criteria for Adverse Events, version 4 scale (CTCAE). Others have reported a 6% incidence of rectal bleeding (using clinician-rated scale) following EBRT and HDR brachytherapy [ 15 ], but the actual incidence as reported by patients could be higher and is likely to vary depending on treatment received.…”

Simulation of an HDR “Boost” with Stereotactic Proton versus Photon Therapy in Prostate Cancer: A Dosimetric Feasibility Study

“…Prostate gland size (commonly defined as .60 cm 3 ) remains a relative contraindication to brachytherapy according to the ABS. While several studies have called this recommendation into question [34,[42][43][44][45], achieving an adequate dose distribution for larger prostate glands remains a challenge, particularly for less experienced brachytherapists. Furthermore, patients with larger prostate glands are more likely to be symptomatic often making them unsuitable candidates for PB.…”

“…To create an equal comparison between SBPT and SBXT plans, target coverage and dose heterogeneity of the CTV (prostate) was evaluated and compared. Target coverage and dose heterogeneity goals shown in Table 1 were designed to reflect HDR-B dosimetry reported in the literature [ 32 – 34 ]. As per ABS guidelines, the CTV (prostate) was required to have 100% of the volume receiving 90% or greater of the prescription dose (V100 ≥ 90%) [ 12 ].…”