Does prostate volume has an impact on biochemical failure in patients with localized prostate cancer treated with HDR boost?

Normal Tissue Integral Dose as a Result of Prostate Radiation Therapy: A Quantitative Comparison Between High-Dose-Rate Brachytherapy and Modern External Beam Radiation Therapy Techniques

Purpose

Quantification of integral radiation dose delivered during treatment for prostate cancer is lacking. We performed a comparative quantification of dose to nontarget body tissues delivered via 4 common radiation techniques: conventional volumetric modulated arc therapy, stereotactic body radiation therapy, pencil-beam scanning proton therapy, and high-dose-rate brachytherapy.

Methods and Materials

Plans for each radiation technique were generated for 10 patients with typical anatomy. For brachytherapy plans, virtual needles were placed to achieve standard dosimetry. Standard planning target volume margins or robustness margins were applied as appropriate. A "normal tissue" structure (entire computed tomography simulation volume minus planning target volume) was generated for integral dose computation. Dose-volume histogram parameters for targets and normal structures were tabulated. Normal tissue integral dose was calculated by multiplying normal tissue volume by mean dose.

Results

Normal tissue integral dose was lowest for brachytherapy. Pencil-beam scanning protons, stereotactic body radiation therapy, and brachytherapy resulted in 17%, 57%, and 91% absolute reductions compared with standard volumetric modulated arc therapy, respectively. Mean nontarget tissues receiving 25%, 50%, and 75% of the prescription dose were reduced by 85%, 76%, and 83% for brachytherapy relative to volumetric modulated arc therapy, by 79%, 64%, and 74% relative to stereotactic body radiation therapy, and 73%, 60%, and 81% relative to proton therapy. All reductions observed using brachytherapy were statistically significant.

Conclusions

High-dose-rate brachytherapy is an effective technique for reducing dose to nontarget body tissues relative to volumetric modulated arc therapy, stereotactic body radiation therapy, and pencil-beam scanning proton therapy.

A Phase 2 Randomized Pilot Study Comparing High-Dose-Rate Brachytherapy and Low-Dose-Rate Brachytherapy as Monotherapy in Localized Prostate Cancer

Purpose

To compare health-related quality of life (HRQOL) of high-dose-rate brachytherapy (HDRB) versus low dose-rate brachytherapy (LDRB) for localized prostate cancer in a multi-institutional phase 2 randomized trial.

Methods and Materials

Men with favorable-risk prostate cancer were randomized between monotherapy brachytherapy with either Iodine-125 LDRB to 144 Gy or single-fraction Iridium-192 HDRB to 19 Gy. HRQOL and urinary toxicity were recorded at baseline and at 1, 3, 6, and 12 months using the Expanded Prostate Cancer Index Composite (EPIC)-26 scoring and the International Prostate Symptom Score (IPSS). Independent samples t test and mixed effects modeling were performed for continuous variables. Time to IPSS resolution, defined as return to its baseline score ±5 points, was calculated using Kaplan-Meier estimator curves with the log-rank test. A multiple-comparison adjusted P value of ≤.05 was considered significant.

Results

LDRB and HDRB were performed in 15 and 16 patients, respectively, for a total of 31 patients. At 3 months, patients treated with LDRB had a higher IPSS score (mean, 15.5 vs 6.0, respectively; P = .003) and lower EPIC urinary irritative score (mean, 69.2 vs 85.3, respectively; P = .037) compared with those who received HDRB. On repeated measures at 1, 3, 6, and 12 months, the IPSS (P = .003) and EPIC urinary irritative scores (P = .019) were significantly better in the HDR arm, translating into a lower urinary toxicity profile. There were no significant differences in the EPIC urinary incontinence, sexual, or bowel habit scores between the 2 groups at any measured time point. Time to IPSS resolution was significantly shorter in the HDRB group (mean, 2.0 months) compared with the LDRB group (mean, 6.0 months; P = .028).

Conclusions

HDRB monotherapy is a promising modality associated with a lower urinary toxicity profile and higher HRQOL in the first 12 months compared with LDRB.

Patient-reported health-related quality of life outcomes after HDR brachytherapy between small (<60 cc) and large (≥60 cc) prostate glands

PURPOSE

Patients with large prostate glands are underrepresented in clinical trials incorporating brachytherapy due to concerns for excessive toxicity. We sought to compare health-related quality of life (HRQOL) outcomes between small (<60 cc) and large (≥60 cc) prostates treated with high-dose-rate brachytherapy (HDR-B).

METHODS AND MATERIALS

One hundred thirty patients at Emory University were treated with HDR-B monotherapy (n = 75) or HDR-B in combination with external beam radiation therapy (n = 55). American Urologic Association Symptom Score (AUASS) and expanded prostate cancer index composite for clinical practice (EPIC-CP) scores were recorded. A linear mixed model was performed dichotomizing prostate volume (<60 and ≥ 60 cc) with AUASS, individual EPIC-CP domains (urinary incontinence, urinary irritation/obstruction [UIO], bowel function, sexual function, and vitality/hormonal function), and overall EPIC-CP HRQOL scores.

RESULTS

Median followup was 22.6 months (range 2.2-55.8). The median gland volume for the entire cohort (n = 130), <60 cc cohort (n = 104), and ≥60 cc cohort (n = 26) was 44 cc, 41.1 cc, and 68.0 cc, respectively. There were no baseline differences in HRQOL scores between cohorts. At 2 months, AUASS and UIO scores increased similarly between cohorts (AUASS p = 0.807; UIO p = 0.539), then decreased (longitudinal effect p < 0.001 and p = 0.005, respectively) to remain not significantly different at 12 months (AUASS p = 0.595; UIO p = 0.673). Overall, prostate volume was not significantly associated with change in AUASS (p = 0.403), urinary incontinence (p = 0.322), UIO symptoms (p = 0.779), bowel symptoms (p = 0.757), vitality/hormonal symptoms (p = 0.503), or overall HRQOL (p = 0.382).

CONCLUSIONS

In appropriately selected patients, HDR-B appears well tolerated in patients with ≥60 cc prostate glands without an increase in patient-reported toxicity. Volume should not be a strict contraindication in those with adequate baseline function.