Favorable preservation of erectile function after prostate brachytherapy for localized prostate cancer

PURPOSE

We analyzed the rate of preserved potency after prostate brachytherapy (PB) with radioactive seeds and the impact of patient comorbidities on post-PB erectile dysfunction (ED).

METHODS

We included 627 patients who were assessed for pre- and postimplant potency between 2005 and 2017. Assessment was based on the Common Terminology Criteria for Adverse Events Scale (CTCAEs). Logistic regression models were used to assess clinical predictors of preserved potency after PB defined as having sufficient erections for sexual activity with or without the need of oral pharmacologic assistance. Covariates included age, diabetes (DM), hypertension (HTN), dyslipidemia (DLP), coronary artery disease (CAD), International Prostate Symptom Score (IPSS), prostate volume, and Cancer of the Prostate Risk Assessments (CAPRA) score. Patients on androgen deprivation therapy or using five alpha reductase inhibitors were excluded from analyses.

RESULTS

Post-PB potency was assessed at an average of 6 months (n = 627), 1 year (n = 538), 2 years (=440), 4 years (n = 272), and 5 years (n = 124). At 2 and 5 years, post-PB potency was preserved in 87% and 84% of patients, respectively. When adjusting for all available covariates, advanced age, pre-PB potency, and the presence of vascular comorbidities (HTN, DM, and DLP) were all predictors of potency at 2 years after PB (all p < 0.01). When performing a sensitivity analysis for vascular comorbidities, the presence of DM had the strongest impact on ED than either HTN or DLP (p < 0.01).

CONCLUSION

More than 84% of patients had preserved potency 5 years after PB. Advanced age, pre-PB potency, and vascular comorbidities had a statistically significant impact on potency after PB.

Transperineal mapping biopsy improves selection of brachytherapy boost for men with localized prostate cancer

PURPOSE

To determine if transperineal mapping biopsy (TPMB) can improve the selection of brachytherapy alone (BT) or brachytherapy boost (BTB) in men with localized prostate cancer.

METHODS AND MATERIALS

Two hundred and eighteen men underwent TPMB with a mean of 48.6 cores retrieved. Comparisons were made between prebiopsy risk features and biopsy results to treatment choice with associations tested with ANOVA (bootstrap), χ² test (Pearson), and linear regression. Survival estimates were tested by the Kaplan-Meier method with comparisons by log rank.

RESULTS

Mean age, prostate specific antigen (PSA), prostate specific antigen density (PSAD), and prostate volume were 67.2 years, 8.1 ng/mL, 0.19, and 50.3 cc, respectively. 105 (48.2%) biopsies were positive for Gleason Group (GG) 1: 34 (32.4%), 2: 21 (20%), 3: 31 (29.5%), 4: 7 (6.7%), and 5: 12 (11.4%). The mean number of positive cores (PCs) was 7.3 (median 6, range 1-37). Men with six or more PCs had higher PSA (11.3 vs. 6.0 ng/mL, p = 0.025) and PSAD (0.34 vs. 0.13, p = 0.013). Overall brachytherapy was used in 74 (70.5%) as either monotherapy or boost therapy. Men with BTB had higher PSA (9.7 vs. 6.7 ng/mL, p = 0.029), PSAD (0.27 vs. 0.16, p = 0.007), GG (3.3 vs. 1.8, p < 0.001), more bilateral disease (75.9% vs. 55.6%, odds ratio 3.9, p = 0.008), and PCs (10.9 vs. 4.4, p < 0.001). On linear regression, only GG (p = 0.008) and PCs (p = 0.044) were associated with BTB. Biochemical-free failure at 5 years was 92.7%.

CONCLUSIONS

TPMB improves the selection of patients for BTB. Men with more PCs are more likely to have BTB. Restricting the need for BTB to those with greater volume prostate cancer may reduce radiation side effects.

Does supplemental external beam radiation therapy impact urinary, bowel, and erectile function following permanent prostate brachytherapy?: results of two prospective randomized trials

Purpose

To evaluate the impact of supplemental external beam radiation therapy (EBRT) prior to permanent prostate brachytherapy on long term urinary, bowel, and erectile function.

Material and methods

Patient administered urinary, bowel, and erectile quality of life (QoL) instrument were obtained prior to treatment and following brachytherapy. The study population was comprised of the 457 patients who were alive as of June 2016, had been randomized to two markedly different supplemental EBRT dose regimens and a third arm without supplemental EBRT, and had completed the June 2016 QoL survey. The need for urinary or bowel surgical intervention was prospectively recorded during routine follow-up. Multiple parameters were evaluated for effect on outcomes.

Results

The urinary catheter was removed on day 0 in 92.1% of patients and 0.4% required a post-implant transurethral prostatic resection (TURP). On average, the International Prostate Symptom Score (IPSS) normalized at week 14. The 10-year rate of urethral strictures was 5.3%. No significant differences were discerned between baseline and post-implant rectal function assessment score (RFAS), and no patient developed a rectal ulcer or fistula. The 10-year potency preservation rate was 50.3%. Supplemental EBRT did not affect urinary, bowel, or erectile function. Urethral strictures were most closely related to bulbomembranous urethral brachytherapy doses, post-implant rectal function to pre-implant hemorroidal bleeding, and RFAS and erectile function to pre-brachytherapy international index of erectile function and age.

Conclusions

Supplemental EBRT did not significantly effect catheter dependency, IPSS resolution, urethral stricture rate, the need for post-implant TURP, bowel, or erectile function. Careful attention to brachytherapy dose distributions appears to be most important in minimizing post-brachytherapy morbidity.

Long-Term Endoscopic Follow-Up of Patients with Chronic Radiation Proctopathy after Brachytherapy for Prostate Cancer

Background. Chronic radiation proctopathy (CRP) is late toxicity and associated with morbidity. Aim. To investigate the predictors of prognosis in patients with CRP after brachytherapy (BT). Methods. One hundred four patients with prostate cancer were treated with BT or BT followed by external-beam radiotherapy (BT + EBRT). We retrospectively investigated the 5-year incidence of rectal bleeding and endoscopic findings of CRP using the Vienna Rectoscopy Score (VRS). Twenty patients with VRS ≥ 1 were divided into the improved VRS group without treatment, unchanged VRS group, and treated group. The parameters associated with alteration of VRS were analyzed. Results. The incidence of rectal bleeding was 24%. The risk of rectal bleeding was higher in patients treated with BT + EBRT compared to those treated with BT (p < 0.0001). The incidence of superficial microulceration was higher in the improved VRS group than in the unchanged VRS group (p < 0.05). The incidence of multiple confluent telangiectasia or superficial ulcers > 1 cm² was higher in the treated group than in both the improved and unchanged VRS groups (p < 0.05). Conclusions. Patients treated with BT + EBRT have a high risk of CRP. Endoscopic findings were useful for prognostic prediction of CRP.

Time Course and Accumulated Risk of Severe Urinary Adverse Events After High- Versus Low-Dose-Rate Prostate Brachytherapy With or Without External Beam Radiation Therapy

PURPOSE

Severe urinary adverse events (UAEs) include surgical treatment of urethral stricture, urinary incontinence, and radiation cystitis. We compared the incidence of grade 3 UAEs, according to the Common Terminology Criteria for Adverse Events, after low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy, as well as after LDR plus external beam radiation therapy (EBRT) and HDR plus EBRT.

METHODS AND MATERIALS

Men aged >65 years with nonmetastatic prostate cancer were identified from the Surveillance, Epidemiology, and End Results-Medicare database who were treated with LDR (n=12,801), HDR (n=685), LDR plus EBRT (n=8518), or HDR plus EBRT (n=2392). The populations were balanced by propensity weighting, and the Kaplan-Meier incidence of severe UAEs was compared. Propensity-weighted Cox proportional hazards models were used to compare the adjusted hazard of UAEs. These UAEs were compared with those in a cohort of men not treated for prostate cancer.

RESULTS

Median follow-up was 4.3 years. At 8 years, the propensity-weighted cumulative UAE incidence was highest after HDR plus EBRT (26.6% [95% confidence interval, 23.8%-29.7%]) and lowest after LDR (15.7% [95% confidence interval, 14.8%-16.6%]). The absolute excess risk over nontreated controls at 8 years was 1.9%, 3.8%, 8.4%, and 12.9% for LDR, HDR, LDR plus EBRT, and HDR plus EBRT, respectively. These represent numbers needed to harm of 53, 26, 12, and 8 persons, respectively. The additional risk of development of a UAE related to treatment for LDR, LDR plus EBRT, and HDR plus EBRT was greatest within the 2 years after treatment and then continued to decline over time. Beyond 4 years, the risk of development of a new severe UAE matched the baseline risk of the control population for all treatments.

CONCLUSIONS

Toxicity differences were observed between LDR and HDR, but the differences did not meet statistical significance. However, combination radiation therapy (either HDR plus EBRT or LDR plus EBRT) increases the risk of severe UAEs compared with HDR alone or LDR alone. The highest increased risk of urinary toxicity occurs within the 2 years after therapy and then declines to an approximately 1% increase in incidence per year.

Late urinary side effects 10 years after low-dose-rate prostate brachytherapy: population-based results from a multiphysician practice treating with a standardized protocol and uniform dosimetric goals

PURPOSE

To determine late urinary toxicity (>12 months) in a large cohort of uniformly treated low-dose-rate prostate brachytherapy patients.

METHODS AND MATERIALS

From 1998 to 2009, 2709 patients with National Comprehensive Cancer Network-defined low-risk and low-tier intermediate-risk prostate cancer were treated with Iodine 125 ((125)I) low-dose-rate prostate brachytherapy; 2011 patients with a minimum of 25 months of follow-up were included in the study. Baseline patients, treatment, implant factors, and late urinary toxicity (Radiation Therapy Oncology Group [RTOG] grading system and International Prostate Symptom Score [IPSS]) were recorded prospectively. Time to IPSS resolution, late RTOG genitourinary toxicity was examined with Kaplan-Meier and log-rank tests. Cox proportional hazards regression was done for individual covariates and multivariable models.

RESULTS

Median follow-up was 54.5 months (range, 2-13 years). Actuarial toxicity rates reached 27% and 10% (RTOG ≥2 and ≥3, respectively) at 9-13 years. Symptoms resolved quickly in the majority of patients (88% in 6-12 months). The prevalence of RTOG 0, 1, 2, 3, and 4 toxicity with a minimum of 7 years' follow-up was 70%, 21%, 6.4%, 2.3%, and 0.08%, respectively. Patients with a larger prostate volume, higher baseline IPSS, higher D90, acute toxicity, and age >70 years had more late RTOG ≥2 toxicity (all P≤.02). The IPSS resolved slower in patients with lower baseline IPSS and larger ultrasound prostate volume, those not receiving androgen deprivation therapy, and those with higher D90. The crude rate of RTOG 3 toxicity was 6%. Overall the rate of transurethral resection of the prostate was 1.9%; strictures, 2%; incontinence, 1.3%; severe symptoms, 1.8%; late catheterization, 1.3%; and hematuria, 0.8%. The majority (80%) resolved their symptoms in 6-12 months.

CONCLUSION

Long-term urinary toxicity after brachytherapy is low. Although actuarial rates increase with longer follow-up (27% RTOG 2 and 10% RTOG 3 at 13 years), symptoms resolve relatively quickly; between 5 and 13 years' follow-up, >90% of patients have minimal urinary toxicity. Refining patient selection criteria, planning, and treatment delivery may further reduce toxicity.

Influence of body mass index and periprostatic fat on rectal dosimetry in permanent seed prostate brachytherapy

PURPOSE

We examined the influence of body mass index (BMI) and body fat distribution on rectal dose in patients treated with permanent seed brachytherapy for localized prostate cancer.

METHODS AND MATERIALS

We analyzed 213 patients treated with I125 seed brachytherapy for localized prostate cancer. BMI and rectal dosimetry data for all patients were available. Data on visceral and subcutaneous fat distribution at the level of the iliac crest (n = 140) as well as the distribution of periprostatic and subcutaneous fat at the symphysis pubis level were obtained (n = 117). Fat distribution was manually contoured on CT on day 30 after brachytherapy. The correlation between BMI, fat distribution and rectal dose (R100 (in cc), R150 (cc), D2 (Gy)) was analyzed using the Spearman correlation coefficient. Differences in rectal dose between tertiles of body fat distribution were calculated using nonparametric tests.

RESULTS

Periprostatic adipose was only weakly correlated with BMI (r = 0.0.245, p = 0.008) and only weakly correlated with the other fat measurements (r = 0.31-0.37, p < 0.001). On the other hand, BMI was correlated with all other fat measurements (≥0.58, p < 0.001). All the other fat measurements were strongly correlated with each other (r = 0.5-0.87, p < 0.001). Patients with an R100 of >1.3 cc (23% of patients) had less visceral fat (p = 0.004), less subcutaneous fat at the level of the iliac crest (p = 0.046) and a lower BMI (26.8 kg/m2 vs. 28.5 kg/m2, p = 0.02) than patients with an R100 of <1.3 cc. Results were very similar when comparing an R100 of >1.0 cc (34% of patients) across the tertiles. None of the tested linear regression models were predictive (max 12%) of dose to the rectum.

CONCLUSION

Dose to the rectum is dependent on BMI and body fat distribution. Periprostatic fat does not influence rectal dose. Dose to the rectum remains difficult to predict and depends on many factors, one of which is body fat distribution.