Radiation treatment for patients with intermediate-risk prostate cancer

Raman spectroscopy and supervised learning as a potential tool to identify high-dose-rate-brachytherapy induced biochemical profiles of prostate cancer

High-dose-rate-brachytherapy (HDR-BT) is an increasingly attractive alternative to external beam radiation-therapy for patients with intermediate risk prostate cancer. Despite this, no bio-marker based method currently exists to monitor treatment response, and the changes which take place at the biochemical level in hypo-fractionated HDR-BT remain poorly understood. The aim of this pilot study is to assess the capability of Raman spectroscopy (RS) combined with principal component analysis (PCA) and random-forest classification (RF) to identify radiation response profiles after a single dose of 13.5 Gy in a cohort of nine patients. We here demonstrate, as a proof-of-concept, how RS-PCA-RF could be utilised as an effective tool in radiation response monitoring, specifically assessing the importance of low variance PCs in complex sample sets. As RS provides information on the biochemical composition of tissue samples, this technique could provide insight into the changes which take place on the biochemical level, as result of HDR-BT treatment.

Effect of Radiation Treatment at a High-Volume Center on Outcomes in Intermediate-Risk Prostate Cancer: An Analysis of the National Cancer Database

OBJECTIVE

To investigate the effect of radiation treatment at a high-volume center on overall survival in men with intermediate-risk prostate cancer.

METHODS

From 2004-2015, 430,347 patients with intermediate-risk prostate cancer were identified in the NCDB. Radiation case volume (RCV) of each hospital was calculated based on number of patients treated. After excluding certain patients including those with metastatic disease, our final analysis population included 116,091 intermediate-risk prostate cancer patients receiving radiation therapy (RT) or radiation with androgen deprivation therapy (RT+ADT). Characteristics analyzed include age, race, distance to treatment facility, Charlson-Deyo Score (CDS), and socioeconomic factors. Primary outcome was overall survival (OS). 5-year survival rates were estimated using the Kaplan-Meier method. Adjusted hazard ratios (HR) with 95% confidence intervals (CI) were computed using multivariate analysis (MVA). Cox regression and propensity score-matched (PSM) analysis was performed.

RESULTS

Median follow up was 63.5 months and estimated 5-year OS was 90.1% at high RCV centers and 88.2% at low RCV centers (p<0.0001). Treatment at high RCV facility was associated with significantly lower mortality compared to treatment at a low RCV facility on MVA and PSM analysis. The survival benefit of treatment at a high RCV facility remained when high RCV facilities were defined as those above the 80^th, 90^th, and 95^th percentile in patient volume (p<0.05).

CONCLUSIONS

Treatment at a high radiation case volume facility is associated with improved OS in patients with radiation-treated intermediate-risk prostate cancer. This survival benefit is important to consider when choosing a treatment center for radiation therapy.

The Natural History of Erectile Dysfunction After Prostatic Radiotherapy: A Systematic Review and Meta-Analysis

BACKGROUND

Erectile dysfunction (ED) after treatment for prostate cancer with radiotherapy (RT) is well known, and pooled estimates of ED after RT will provide more accurate patient education.

AIM

To systematically evaluate the natural history of ED in men with previous erectile function after prostate RT and to determine clinical factors associated with ED.

METHODS

We performed a review of the PubMed and Medline, Embase, Cochrane Library, and Web of Science databases in April 2016 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Identified reports included a measurement of ED before and after prostate RT. Two hundred seventy-eight abstracts were screened and 105 publications met the criteria for inclusion. Only men with known erectile function before RT were included in the analysis.

OUTCOME

ED after RT of the prostate.

RESULTS

In total, 17,057 men underwent brachytherapy (65%), 8,166 men underwent external-beam RT (31%), and 1,046 men underwent both (4%). Seven common instruments were used to measure ED, including 23 different cutoffs for ED. The Sexual Health Inventory for Men (SHIM) was used in 31 studies (30%). Pooled estimates of SHIM-confirmed ED (score <10-17) suggested the prevalence of ED after RT is 34% of men (95% CI = 0.29-0.39) at 1 year and 57% (95% CI = 0.53-0.61) at 5.5 years. Compared with brachytherapy, studies of the two types of radiation increased the proportion of new-onset ED found by 12.3% of studies (95% CI = 2.3-22.4). For every 10% who were lost to follow-up, the proportion of ED reported increased by 2.3% (95% CI = 0.03-4.7).

CLINICAL IMPLICATIONS

ED is common regardless of RT modality and increases during each year of follow-up. Using the SHIM, ED is found in approximately 50% patients at 5 years.

STRENGTHS AND LIMITATIONS

The strengths of this systematic review include strict inclusion criteria of studies that measured baseline erectile function, no evidence for large effect size bias, and a large number of studies, which allow for modeling techniques. However, all data included in this analysis were observational, which leaves the possibility that residual confounding factors increase the rates of ED.

CONCLUSION

Definitions and measurements of ED after RT vary considerably in published series and could account for variability in the prevalence of reported ED. Loss to follow-up in studies could bias the results to overestimate ED. Gaither TW, Awad MA, Osterberg EC, et al. The Natural History of Erectile Dysfunction After Prostatic Radiotherapy: A Systematic Review and Meta-Analysis. J Sex Med 2017;14:1071-1078.

Dosimetric comparison between the prostate intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans using the planning target volume (PTV) dose–volume factor

Background

We demonstrated that our proposed planning target volume (PTV) dose–volume factor (PDVF) can be used to evaluate the PTV dose coverage between the intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans based on 90 prostate patients.

Purpose

PDVF were determined from the prostate IMRT and VMAT plans to compare their variation of PTV dose coverage. Comparisons of the PDVF with other plan evaluation parameters such as D5%, D95%, D99%, Dmean, conformity index (CI), homogeneity index (HI), gradient index (GI) and prostate tumour control probability (TCP) were carried out.

Methods and materials

Prostate IMRT and VMAT plans using the 6 MV photon beams were created from 40 and 50 patients, respectively. Dosimetric indices (CI, HI and GI), dose–volume points (D5%, D95%, D99% and Dmean) and prostate TCP were calculated according to the PTV dose–volume histograms (DVHs) of the plans. All PTV DVH curves were fitted using the Gaussian error function (GEF) model. The PDVF were calculated based on the GEF parameters.

Results

From the PTV DVHs of the prostate IMRT and VMAT plans, the average D99% of the PTV for IMRT and VMAT were 74·1 and 74·5 Gy, respectively. The average prostate TCP were 0·956 and 0·958 for the IMRT and VMAT plans, respectively. The average PDVF of the IMRT and VMAT plans were 0·970 and 0·983, respectively. Although both the IMRT and VMAT plans showed very similar prostate TCP, the dosimetric and radiobiological results of the VMAT technique were slightly better than IMRT.

Conclusion

The calculated PDVF for the prostate IMRT and VMAT plans agreed well with other dosimetric and radiobiological parameters in this study. PDVF was verified as an alternative of evaluation parameter in the quality assurance of prostate treatment planning.

Intravesical Therapies for Radiation Cystitis

Objective

The purpose of this study was to summarize developments during the last decade in intravesical treatments for radiation cystitis. Radiation used to treat pelvic malignancies inadvertently damages the urinary bladder leading to acute as well as chronic symptoms. Late sequelae may take years to develop and include storage symptoms and hematuria, which may be life-threatening in severe cases. Conservative measures, surgical interventions, and systematically or intravesically administered agents represent treatment choices.

Methods

MEDLINE and PubMed were searched to retrieve clinical data on the subject, published in peer-reviewed journals from 2002 onwards.

Results

Historically referenced intravesical treatments such as aluminium salts and formalin, were not investigated in recent studies. The replenishment of the glycosaminoglycan layer of the bladder mucosa shows promise in reducing acute symptoms and possibly long-term bladder damage, but needs further investigation. Botulinum toxin also represents a new alternative treatment for radiation cystitis but its mechanism of action and efficacy should be evaluated in future trials.

Conclusion

There is a paucity of data in recent literature regarding the management of radiation cystitis, at least by means of intravesical agents. The replenishment of the glycosaminoglycan layer of the bladder mucosa and the administration of botulinum toxin show promise, but need further investigation.

Differential post-prostatectomy cancer-specific survival of occult T3 vs. clinical T3 prostate cancer: Implications for managing patients upstaged on prostate magnetic resonance imaging

PURPOSE/OBJECTIVE

Long-term androgen deprivation therapy (ADT) was proven in randomized trials to be superior to short-term ADT for radiation-managed patients who have clinical T3 (cT3) disease, but it is unknown whether patients with T3 disease seen only on magnetic resonance imaging require similarly aggressive treatment. We attempted to study this issue by analogy by comparing the long-term post-prostatectomy survival of patients with cT3 disease versus cT1/T2 disease upstaged to pathologic T3 disease.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was used to identify 60,165 men diagnosed with prostate adenocarcinoma between 1995 and 2002 who underwent prostatectomy. Prostate cancer-specific mortality (PCSM) was evaluated by stage after adjusting for grade, marital status, race, sex, year of diagnosis, and age.

RESULTS

The median follow-up was 10.5 years. Patients with cT1/T2 but pathologic T3a disease had significantly better 10-year PCSM than men with cT3 disease had (3.0% vs. 9.9%, adjusted hazard ratio [AHR] = 0.420, P<0.001), but they had worse PCSM than men with pathologic T2 disease had (3.0% vs. 0.91%, AHR = 2.53, P<0.001). Of patients with occult T3a disease, those with low-grade/intermediate-grade disease (Gleason score 7 or less) had a slightly higher 10-year PCSM when compared with those with pathologic T2 disease (1.34% vs. 0.91%, AHR = 1.69, P<0.001). Patients with cT1/T2 and pathologic T3b disease had similar PCSM as men presenting with cT3 disease (11.0% vs. 9.86%, AHR = 1.14 [0.862, 1.52], P = 0.353).

CONCLUSIONS

Patients with occult T3a disease had less than half the risk of PCSM as those with cT3 disease, and a subset of those men had similar risk as patients with pathologic T2 disease. Therefore, it is possible that radiation-managed patients with low-grade/intermediate-grade T3a disease by magnetic resonance imaging only might not require long-term ADT. However, patients with occult T3b or high-grade occult T3a disease have similar PCSM as that of those presenting with cT3 disease, so they should be treated as aggressively, including long-course ADT when managed by radiation.