Prostate Cancer Radiation Therapy: What Do Clinicians Have to Know?

Recent advances and future perspectives in the therapeutics of prostate cancer

Prostate cancer (PC) is one of the most common cancers in males and the fifth leading reason of death. Age, ethnicity, family history, and genetic defects are major factors that determine the aggressiveness and lethality of PC. The African population is at the highest risk of developing high-grade PC. It can be challenging to distinguish between low-risk and high-risk patients due to the slow progression of PC. Prostate-specific antigen (PSA) is a revolutionary discovery for the identification of PC. However, it has led to an increase in over diagnosis and over treatment of PC in the past few decades. Even if modifications are made to the standard PSA testing, the specificity has not been found to be significant. Our understanding of PC genetics and proteomics has improved due to advances in different fields. New serum, urine, and tissue biomarkers, such as PC antigen 3 (PCA3), have led to various new diagnostic tests, such as the prostate health index, 4K score, and PCA3. These tests significantly reduce the number of unnecessary and repeat biopsies performed. Chemotherapy, radiotherapy, and prostatectomy are standard treatment options. However, newer novel hormone therapy drugs with a better response have been identified. Androgen deprivation and hormonal therapy are evolving as new and better options for managing hormone-sensitive and castration-resistant PC. This review aimed to highlight and discuss epidemiology, various risk factors, and developments in PC diagnosis and treatment regimens.

Application of Hydrogel Spacer SpaceOAR Vue for Prostate Radiotherapy

Damage in the surrounding structures, including the rectum, due to unintended exposure to radiation is a large burden to bear for patients who undergo radiation therapy for prostate cancer. The use of injectable rectal spacers to distance the anterior rectum from the prostate is a potential strategy to reduce the dose of unintended radiation to the rectum. Hydrogel spacers are gaining increasing popularity in the treatment regimen for prostate cancer. After FDA approval of SpaceOAR, specialists are receiving an increasing number of referrals for hydrogel placements. In this paper, we review hydrogel spacers, the supporting clinical data, the best practices for hydrogel placement, and the risk of adverse events.

A Systematic Review of the Treatment Outcomes among Prostate Cancer Patients in Africa

Prostate cancer (PCa) is associated with a significant public health burden in Africa. This systematic review aimed to assess treatment outcomes among PCa patients in Africa. A systematic search of the literature was conducted from 1 December 2021 to 31 March 2022 to identify relevant published studies. PubMed, EMBASE, CINAHL, and Google Scholar databases were used. Twenty-four studies met the inclusion criteria, and the mean age was 68 years. Localized and locally advanced diseases had relatively higher overall survival than metastatic diseases. In metastatic disease, the mean overall five-year survival was 42% which is shorter than the Asian population (61.9%).

Evaluation of hyaluronic acid gel dissolution with hyaluronidase in an in-vitro prostate cancer model

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Hyaluronic acid (HA) is an implantable rectum spacer used to decrease rectal radiation dose in prostate cancer radiotherapy.

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Hyaluronidase (HAS) is an enzyme that degrades HA, when wrongly positioned.

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A ratio of HA:HAS of 1:2 has already a decrease of half of volume on the 2nd day.

Aim

To determine a dose response relationship of disintegration of a hyaluronic acid (HA) and hyaluronidase (HAS) used in prostate cancer radiotherapy.

Materials and methods

Five in-vitro models are applicated with 3 ml (ml) HA. For dissolution varying doses of HAS were used: 6 ml, 3 ml, 1.5 ml, and 0 ml. One ml contains 150 International Units (IU). Each HAS was added with saline till the complementary amount of 6 ml. One phantom was solely implanted with a HA 3 ml acting as a control. Length, width and height were measured on different time points: 1st day 4 times, 2nd day 3 times, third day 2 times, and then once daily during one week, with a final measurement 2 weeks after implantation. The experiments were performed in duplicate to exclude variations and confirm the results.

Results

The fastest dissolution was observed with the highest concentration of HAS, already observed at the first time point 2 h after implantation, with volume decrease of 50% on the second day, and less than 1 ml residue (33%) on day 4. The 2 other concentrations of HAS also showed a volume decrease, with less than 2 ml (66%) on day 4. All the applied quantities of HAS are observed with a residue of less than 1 ml after 7 days. After 14 days the control phantom and the saline filled one remains on steady state volume (3 ml).

Conclusions

A dose response was observed by HAS injection: highest volumes of HAS dissolute most swiftly. Using a ratio of HA:HAS of 1:2 results in a decrease to half of initial volume within 24 h. This is of special interest when used in clinical practice following erroneous positioning, and dissolution is urgently needed.

Diagnostic significance of reassessment of prostate biopsy specimens by experienced urological pathologists at a high-volume institution

In prostate cancer, accurate diagnosis and grade group (GG) decision based on biopsy findings are essential for determining treatment strategies. Diagnosis by experienced urological pathologists is recommended; however, their contribution to patient benefits remains unknown. Therefore, we analyzed clinicopathological information to determine the significance of reassessment by experienced urological pathologists at a high-volume institution to identify factors involved in the agreement or disagreement of biopsy and surgical GGs. In total, 1325 prostate adenocarcinomas were analyzed, and the GG was changed in 452/1325 (34.1%) cases (359 cases were upgraded, and 93 cases were downgraded). We compared the highest GG based on biopsy specimens, with the final GG based on surgical specimens of 210 cases. The agreement rate between the surgical GG performed and assessed in our institute and the highest biopsy GG assessed by an outside pathologist was 34.8% (73/210); the agreement rate increased significantly to 50% (105/210) when biopsy specimens were reevaluated in our institute (chi-square test, P < 0.01). Multivariate logistic regression analysis showed that only the length of the lesion in the positive core with the highest GG in the biopsy was a significant factor for determining the agreement between biopsy GG and surgical GG, with an odds ratio of 1.136 (95% confidence interval: 1.057-1.221; P < 0.01). Thus, reassessment by experienced urological pathologists at high-volume institutions improved the agreement rate. However, it should be noted there is a high probability of discordance between a small number of lesions or short lesions and surgical GG.

Time-resolved QA and brachytherapy applicator commissioning: Towards the clinical implementation

PURPOSE

Brachytherapy has a busy workflow relying on manual steps to ensure accurate delivery of the treatment. Systematic treatment errors have been reported due to faulty equipment, inadequate quality assurance (QA) and applicator commissioning methods. This study describes the use of a novel method, the Iridium Imaging System for QA (IrIS - QA), to automate and improve the applicator commissioning for HDR ¹⁹²Ir brachytherapy.

METHODS AND MATERIALS

A 3D printed holder attached to an Imaging Panel (IP) has been developed to: (1) acquire a high-definition projection of the applicator using the gamma rays of the ¹⁹²Ir source for imaging; (2) Track the source within the applicator verifying in a time-resolved manner the dwell positions and dwell times with a high resolution. Results obtained for two applicator models are described in this manuscript.

RESULTS

IrIS-QA is capable of measuring the dwell times with an accuracy better than 0.1 s and interdwell distances with submillimetre precision. The applicators tested in the study showed good agreement between planned and delivered dwell times and positions, with mean and maximum dwell position deviations below 0.5 mm and 1.3 mm, respectively. Dwell time measurements showed agreement superior to 0.05 s except for the first dwell position for which up to 0.15 s differences were observed.

CONCLUSIONS

IrIS-QA is a compact system that includes many features necessary to improve the accuracy and efficiency of applicator commissioning and daily QA. No commercial system exists with similar capabilities. IrIS-QA is intended to replace current clinical procedures using film dosimetry.

Abnormal within- and cross-networks functional connectivity in different outcomes of herpes zoster patients

Neuroimaging studies have displayed aberrant brain activities in individual sensory- and emotional-linked regions in postherpetic neuralgia (PHN) patients. However, multi-dimensional dysfunction in chronic pain may rely on the interplay between networks. Little is known about the changes in the functional architecture of resting state networks (RSNs) in PHN. In this cross-sectional study, we recruited 31 PHN patients, 33 RHZ patients and 34 HCs; all participants underwent resting-state functional magnetic resonance imaging scans. We investigated the differences of within- and cross-network connectivities between different outcomes of HZ patients [including PHN and recuperation from herpes zoster (RHZ)] and healthy controls (HCs) so as to extract a characteristic network pattern of PHN. The abnormal network connectivities were then correlated with clinical variables in respective groups. PHN and RHZ patients could be similarly characterized by abnormal within-default mode network (DMN), DMN-salience network (SN) and SN-basal ganglia network (BGN) connectivity relative to HCs. Of note, compared with RHZ patients, PHN patients could be characterized by abnormal DMN-BGN and within-BGN connectivity. Furthermore, the within-DMN connectivity was associated with pain-induced emotional scores among PHN patients. Our study presented that network-level imbalance could account for the pain-related dysfunctions in different outcomes of herpes zoster patients. These insights are potentially useful for understanding neuromechanism of PHN and providing central therapeutic targets for PHN.

Dracocephalum palmatum Stephan extract induces apoptosis in human prostate cancer cells via the caspase-8-mediated extrinsic pathway

Dracocephalum palmatum Stephan is a medicinal plant traditionally used by nomadic people in Eastern Russia; however, research on this plant is currently limited. Recently, although studies have been conducted on the constituents of this plant and their antioxidant effects, data on its various pharmacological activities are still lacking. Thus, this study examined the anticancer potential of the dried leaves of D. palmatum S. (DpL) using human prostate cancer PC-3 cells. The antioxidant potential of DpL was evaluated by estimating the total flavonoid and total phenolic content (TFC and TPC, respectively). Additionally, we investigated the effects of the DpL ethyl acetate fraction (DpLE) on cell proliferation, intracellular reactive oxygen species (ROS) generation, apoptosis, and cell cycle arrest in this cell line. The expression levels of superoxide dismutase (SOD)-1, SOD-2, B-cell lymphoma 2 (Bcl-2) and Bcl-2 associated X (Bax) ratio, phospho-protein kinase B (p-AKT), cleaved caspase-8, poly adenosine diphosphate (ADP) ribose polymerase (PARP), and cleaved-PARP were evaluated by western blotting. The results indicated that DpLE causes apoptosis and exerts intracellular ROS-independent anticancer effects on prostate cancer cells, associated with increased SOD-2, cleaved caspase-8, and cleaved-PARP expression and inhibited p-AKT signaling. Thus, DpLE may be a potential resource for the development of promising chemotherapeutic agents for prostate cancer.

MicroRNAs in prostate cancer following radiotherapy: Towards predicting response to radiation treatment

Prostate cancer (PCa) is the second most frequently diagnosed male cancer worldwide. Early diagnosis of PCa, response to therapy and prognosis still represent a challenge. Nearly 60% of PCa patients undergo radiation therapy (RT) which might cause side effects. In spite of numerous researches in this field, predictive biomarkers for radiation toxicity are still not elucidated. MicroRNAs as posttranscriptional regulators of gene expression are shown to be changed during and after irradiation. Manipulation with miRNA levels might be used to modulate response to RT-to reverse radioresistance-to induce radiosensitivity, or if needed, to reduce sensitivity to treatment to avoid side effects. In this review we have listed and described miRNAs involved in response to RT in PCa, and highlighted potential candidates for future biological tests predicting radiation response to RT, with the special focus on side effects of RT. Individual radiation response is a result of the interactions between physical characteristics of radiation treatment and biological background of each patient, and miRNA expression changes among others. According to described literature we concluded that let-7, miR-21, miR-34a, miR-146a, miR-155, and members of miR-17/92 cluster might be promising candidates for biological tests predicting radiosensitivity of PCa patients undergoing radiation treatment, and as future agents for modulation of radiation response. Predictive miRNA panels, especially for acute and late side effects of RT can serve as a starting point for decisions for individualized RT planning. We believe that this review might be one step closer to understanding molecular mechanisms underlying individual radiation response of patients with PCa.

Early health economic analysis of 1.5 T MRI-guided radiotherapy for localized prostate cancer: Decision analytic modelling

BACKGROUND AND PURPOSE

1.5 Tesla magnetic resonance imaging radiotherapy linear accelerator (MR-Linac) is gaining interest for treatment of localized prostate cancer. Clinical evidence is lacking and it therefore remains uncertain whether MR-Linac is cost-effective. An early health economic analysis was performed to calculate the necessary relative reduction in complications and the maximum price of MR-Linac (5 fractions) to be cost-effective compared to 5, 20 and 39 fractionation schedules of external beam radiotherapy (EBRT) and low-dose-rate (LDR) brachytherapy.

MATERIALS AND METHODS

A state transition model was developed for men with localized prostate cancer. Complication rates such as grade ≥2 urinary, grade ≥2 bowel and sexual complications, and utilities were based on systematic literature searches. Costs were estimated from a Dutch healthcare perspective. Threshold analyses were performed to identify the thresholds of complications and costs for MR-Linac to be cost-effective, while holding other outcomes such as biochemical progression and mortality constant. One-way sensitivity analyses were performed to outline uncertainty outcomes.

RESULTS

At €6460 per patient, no reductions in complications were needed to consider MR-Linac cost-effective compared to EBRT 20 and 39 fractions. Compared to EBRT 5 fractions and LDR brachytherapy, MR-Linac was found to be cost-effective when complications are relatively reduced by 54% and 66% respectively. Results are highly sensitive to the utilities of urinary, bowel and sexual complications and the probability of biochemical progression.

CONCLUSIONS

MR-Linac is found to be cost-effective compared to 20 and 39 fractions EBRT at baseline. For MR-Linac to become cost-effective over 5 fractions EBRT and LDR brachytherapy, it has to reduce complications substantially or be offered at lower costs.

Atorvastatin Enhances Inhibitory Effects of Irradiation on Tumor Growth by Reducing MSH2 Expression both in Prostate Cancer Cells and Xenograft Tumor Models

BACKGROUND

Prostate cancer (PCa) is the fourth most common tumor in males.

OBJECTIVE

To investigate effects of atorvastatin (AS) on PCa cells proliferation and clarify the associated mechanisms.

METHODS

PCa cell lines were cultured and treated with irradiation (IR) (4 Gy), AS (6 μg/ml), transfected with Bcl-2 siRNA, and then divided into different groups. Xenograft tumor mouse model was established. Bcl-2 and MSH2 gene transcription and protein expression were evaluated using RT-PCR assay and western blot assay. Plate clone formation assay was employed to examine colony formation. MTT assay was used to detect cell viabilities. Flow cytometry analysis was utilized to verify apoptosis. Co-immunoprecipitation and immuno-fluorescence assay were used to identify interaction between Bcl-2 and MSH2.

RESULTS

IR significantly reduced colony formation, enhanced Bcl-2 and reduced MSH2 gene transcription in PCa cells compared to un-treated cells (p<0.05). AS significantly strengthened radio-therapeutic effects of IR on colony formation, decreased cell apoptosis and increased Bcl-2 gene transcription/protein expression in PCa cells compared to single IR treatment cells (p<0.05). AS combining IR down-regulated MSH2 gene transcription/protein expression in PCa cells compared to single IR treatment cells (p<0.05). Bcl-2 interacted with MSH2 both in PCa cells and tumor tissues administrating with AS. AS enhanced reductive effects of IR on tumor size of Xenograft tumor mice.

CONCLUSION

Atorvastatin administration enhanced inhibitory effects of IR either on PCa cells or on tumor size of Xenograft tumor mice. The inhibitory effects of atorvastatin were mediated by reducing MSH2 expression and triggering interaction between Bcl-2 and MSH2, both in vitro and in vivo levels.

Brachytherapy treatment verification using gamma radiation from the internal treatment source combined with an imaging panel-a phantom study

Brachytherapy has an excellent clinical outcome for different treatment sites. However,in vivotreatment verification is not performed in the majority of hospitals due to the lack of proper monitoring systems. This study investigates the use of an imaging panel (IP) and the photons emitted by a high dose rate (HDR)¹⁹²Ir source to track source motion and obtain some information related to the patient anatomy. The feasibility of this approach was studied by monitoring the treatment delivery to a 3D printed phantom that mimicks a prostate patient. A 3D printed phantom was designed with a template for needle insertion, a cavity ('rectum') to insert an ultrasound probe, and lateral cavities used to place tissue-equivalent materials. CT images were acquired to create HDR¹⁹²Ir treatment plans with a range of dwell times, interdwell distances and needle arrangements. Treatment delivery was verified with an IP placed at several positions around the phantom using radiopaque markers on the outer surface to register acquired IP images with the planning CT. All dwell positions were identified using acquisition times ≤0.11 s (frame rates ≥ 9 fps). Interdwell distances and dwell positions (in relation to the IP) were verified with accuracy better than 0.1 cm. Radiopaque markers were visible in the acquired images and could be used for registration with CT images. Uncertainties for image registration (IP and planning CT) between 0.1 and 0.4 cm. The IP is sensitive to tissue-mimicking insert composition and showed phantom boundaries that could be used to improve treatment verification. The IP provided sufficient time and spatial resolution for real-time source tracking and allows for the registration of the planning CT and IP images. The results obtained in this study indicate that several treatment errors could be detected including swapped catheters, incorrect dwell times and dwell positions.

Comparative dosimetrical analysis of intensity-modulated arc therapy, CyberKnife therapy and image-guided interstitial HDR and LDR brachytherapy of low risk prostate cancer

Background

The objective of the study was to dosimetrically compare the intensity-modulated-arc-therapy (IMAT), Cyber-Knife therapy (CK), single fraction interstitial high-dose-rate (HDR) and low-dose-rate (LDR) brachytherapy (BT) in low-risk prostate cancer.

Materials and methods

Treatment plans of ten patients treated with CK were selected and additional plans using IMAT, HDR and LDR BT were created on the same CT images. The prescribed dose was 2.5/70 Gy in IMAT, 8/40 Gy in CK, 21 Gy in HDR and 145 Gy in LDR BT to the prostate gland. EQD2 dose-volume parameters were calculated for each technique and compared.

Results

EQD2 total dose of the prostate was significantly lower with IMAT and CK than with HDR and LDR BT, D90 was 79.5 Gy, 116.4 Gy, 169.2 Gy and 157.9 Gy (p < 0.001). However, teletherapy plans were more conformal than BT, COIN was 0.84, 0.82, 0.76 and 0.76 (p < 0.001), respectively. The D₂ to the rectum and bladder were lower with HDR BT than with IMAT, CK and LDR BT, it was 66.7 Gy, 68.1 Gy, 36.0 Gy and 68.0 Gy (p = 0.0427), and 68.4 Gy, 78.9 Gy, 51.4 Gy and 70.3 Gy (p = 0.0091) in IMAT, CK, HDR and LDR BT plans, while D_0.1 to the urethra was lower with both IMAT and CK than with BTs: 79.9 Gy, 88.0 Gy, 132.7 Gy and 170.6 Gy (p < 0.001). D₂ to the hips was higher with IMAT and CK, than with BTs: 13.4 Gy, 20.7 Gy, 0.4 Gy and 1.5 Gy (p < 0.001), while D₂ to the sigmoid, bowel bag, testicles and penile bulb was higher with CK than with the other techniques.

Conclusions

HDR monotherapy yields the most advantageous dosimetrical plans, except for the dose to the urethra, where IMAT seems to be the optimal modality in the radiotherapy of low-risk prostate cancer.

Prostate cancer

Prostate cancer is a complex disease that affects millions of men globally, predominantly in high human development index regions. Patients with localized disease at a low to intermediate risk of recurrence generally have a favourable outcome of 99% overall survival for 10 years if the disease is detected and treated at an early stage. Key genetic alterations include fusions of TMPRSS2 with ETS family genes, amplification of the MYC oncogene, deletion and/or mutation of PTEN and TP53 and, in advanced disease, amplification and/or mutation of the androgen receptor (AR). Prostate cancer is usually diagnosed by prostate biopsy prompted by a blood test to measure prostate-specific antigen levels and/or digital rectal examination. Treatment for localized disease includes active surveillance, radical prostatectomy or ablative radiotherapy as curative approaches. Men whose disease relapses after prostatectomy are treated with salvage radiotherapy and/or androgen deprivation therapy (ADT) for local relapse, or with ADT combined with chemotherapy or novel androgen signalling-targeted agents for systemic relapse. Advanced prostate cancer often progresses despite androgen ablation and is then considered castration-resistant and incurable. Current treatment options include AR-targeted agents, chemotherapy, radionuclides and the poly(ADP-ribose) inhibitor olaparib. Current research aims to improve prostate cancer detection, management and outcomes, including understanding the fundamental biology at all stages of the disease.

Prostate cancer

Prostate cancer is a complex disease that affects millions of men globally, predominantly in high human development index regions. Patients with localized disease at a low to intermediate risk of recurrence generally have a favourable outcome of 99% overall survival for 10 years if the disease is detected and treated at an early stage. Key genetic alterations include fusions of TMPRSS2 with ETS family genes, amplification of the MYC oncogene, deletion and/or mutation of PTEN and TP53 and, in advanced disease, amplification and/or mutation of the androgen receptor (AR). Prostate cancer is usually diagnosed by prostate biopsy prompted by a blood test to measure prostate-specific antigen levels and/or digital rectal examination. Treatment for localized disease includes active surveillance, radical prostatectomy or ablative radiotherapy as curative approaches. Men whose disease relapses after prostatectomy are treated with salvage radiotherapy and/or androgen deprivation therapy (ADT) for local relapse, or with ADT combined with chemotherapy or novel androgen signalling-targeted agents for systemic relapse. Advanced prostate cancer often progresses despite androgen ablation and is then considered castration-resistant and incurable. Current treatment options include AR-targeted agents, chemotherapy, radionuclides and the poly(ADP-ribose) inhibitor olaparib. Current research aims to improve prostate cancer detection, management and outcomes, including understanding the fundamental biology at all stages of the disease.

Artemisia kruhsiana leaf extract induces autophagic cell death in human prostate cancer cells

Some species of Artemisia have been reported to induce apoptosis and autophagy, but little is known of the apoptotic and autophagic effects of the stems and leaves of Artemisia kruhsiana Bess. (AkB). This study was conducted to investigate the antioxidant and anti-autophagic effects of the methanol extracts of the stems (EAkBs) and leaves (EAkBl) of AkB on human prostate cancer PC-3 cells. The antioxidant effects of EAkBs and EAkBl were measured using in vitro total flavonoid and total phenolic assays and a free radical scavenging assay. The effects of EAkBl on cell viability, apoptosis, autophagy, intracellular reactive oxygen species (ROS) generation and protein expression levels were also investigated. EAkBl was found to induce apoptosis, autophagy, and intracellular ROS generation in PC-3 cells. In terms of protein levels, EAkBl reduced phospho (p)-protein kinase B (AKT)/AKT, p-mammalian target of rapamycin (mTOR)/mTOR, B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) ratios, and the activations of beclin 1/β-actin and microtubule-associated protein 1A/1B-light chain 3 (LC3) II/LC3 I ratios in PC-3 cells. The results of this study indicate EAkBl has antioxidant and anticancer effects on prostate cancer cells, and that these effects are associated with suppressions of p-AKT, p-mTOR, Bcl-2, and Bax, and the activations of beclin 1 and LC3. Our results indicate EAkBl has potential as a treatment for prostate cancer.

Inguinal hernia in a patient with prostate cancer to be treated with photon radiotherapy

Inguinal hernia should be repaired prior to photon radiotherapy for prostate cancer to avoid exposing the radiosensitive intestinal tract potentially included in hernia sac.

Biological dose summation of intensity-modulated arc therapy and image-guided high-dose-rate interstitial brachytherapy in intermediate- and high-risk prostate cancer

Purpose

To present an alternative method for summing biologically effective doses of intensity-modulated arc therapy (IMAT) as teletherapy (TT), with interstitial high-dose-rate (HDR) brachytherapy (BT) boost in prostate cancer. Total doses using IMAT boost was compared with BT boost using our method.

Material and methods

Initially, 25 IMAT TT plus interstitial HDR-BT plans were included, and additional plans using IMAT TT boost were created. The prescribed dose was 2/44 Gy to the whole pelvis, 2/60 Gy to the prostate and seminal vesicles, and 1 × 10 Gy BT or 2/18 Gy IMAT TT to the prostate. Teletherapy computed tomography (CT) was registered with ultrasound (US) of BT, and the most exposed volume of critical organs in BT were identified on these CT images. The minimal dose of these from IMAT TT was summed with their BT dose, and these EQD₂ doses were compared using BT vs. IMAT TT boost. This method was compared with uniform dose conception (UDC).

Results

D₉₀ of the prostate was significantly higher with BT than with IMAT TT boost: 99.3 Gy vs. 77.9 Gy, p = 0.0034. The D₂ to rectum, bladder, and hips were 50.3 Gy vs. 76.8 Gy (p = 0.0117), 64.7 Gy vs. 78.3 Gy (p = 0.0117), and 41.9 Gy vs. 50.6 Gy (p = 0.0044), while D_0.1 to urethra was 96.1 Gy vs. 79.3 Gy (p = 0.0180), respectively. UDC overestimated D₂ (rectum) by 37% (p = 0.0117), D₂ (bladder) by 5% (p = 0.0214), and underestimated D_0.1 (urethra) by 1% (p = 0.0277).

Conclusions

Based on our biological dose summation method, the total dose of prostate is higher using BT boost than the IMAT. BT boost yields lower rectum, bladder, and hips doses, but higher dose to urethra. UDC overestimates rectum and bladder dose and underestimates the dose to urethra.

Cellular Delivery of Bioorthogonal Pretargeting Therapeutics in PSMA-Positive Prostate Cancer

Prostate cancer is primarily fatal after it becomes metastatic and castration-resistant despite novel combined hormonal and chemotherapeutic regimens. Hence, new therapeutic concepts and drug delivery strategies are urgently needed for the eradication of this devastating disease. Here we report the highly specific, in situ click chemistry driven pretargeted delivery of cytotoxic drug carriers to PSMA(+) prostate cancer cells. Anti-PSMA 5D3 mAb and its F(ab')₂ fragments were functionalized with trans-cyclooctene (TCO), labeled with a fluorophore, and used as pretargeting components. Human serum albumin (ALB) was loaded with the DM1 antitubulin agent, functionalized with PEGylated tetrazine (PEG₄-Tz), labeled with a fluorophore, and used as the drug delivery component. The internalization kinetics of components and the therapeutic efficacy of the pretargeted click therapy were studied in PSMA(+) PC3-PIP and PSMA(-) PC3-Flu control cells. The F(ab')₂ fragments were internalized faster than 5D3 mAb in PSMA(+) PC3-PIP cells. In the two-component pretargeted imaging study, both components were colocalized in a perinuclear location of the cytoplasm of PC3-PIP cells. Better colocalization was achieved when 5D3 mAb was used as the pretargeting component. Consecutively, the in vitro cell viability study shows a significantly higher therapeutic effect of click therapy in PC3-PIP cells when 5D3 mAb was used for pretargeting, compared to its F(ab')₂ derivative. 5D3 mAb has a longer lifetime on the cell surface, when compared to its F(ab')₂ analogue, enabling efficient cross-linking with the drug delivery component and increased efficacy. Pretargeting and drug delivery components were cross-linked via multiple bioorthogonal click chemistry reactions on the surface of PSMA(+) PC cells forming nanoclusters, which undergo fast cellular internalization and intracellular transport to perinuclear locations.

Glucocorticoid receptor upregulation increases radioresistance and triggers androgen independence of prostate cancer

BACKGROUND

Despite the overall success of radiotherapy, a significant number of patients develop radioresistance, which leads to local regional recurrence and distant metastasis. We studied whether repeated radiation treatment promotes androgen-independent survival of prostate cancer (PCa) cells and their metastatic potential. We also studied whether glucocorticoid receptor (GR) increase in radioresistant cells is associated with acquisition of these aggressive characteristics.

METHODS

Radioresistant LNCaP (LNCaPR18) and C4-2 (C4-2R26) PCa sublines were developed by repeated radiation treatments of parental cells. Levels and activations of androgen receptor (AR) and GR in radioresistant PCa cells and respective parental cells were investigated in quantitative real-time polymerase chain reaction/Western blot analyses and immunofluorescence staining. Androgen-independent survival of radioresistant cells was tested in in vitro cell growth assays and the castration-resistant survival of these cell-derived tumors were investigated in mouse xenografts.

RESULTS

Higher GR levels, but lower AR levels were detected in radioresistant cells than in parental cells. Radiation-induced GR upregulation was associated with increased intracellular cyclic adenosine monophosphate. As a consequence of GR activation, LNCaPR18 cells survived well in an androgen-depleted culture condition while parental cells could not. Results of in vivo mouse studies showed survival of LNCaPR18 cell-derived tumors in castrated mice while parental cell-derived tumors regressed. The growth of LNCaPR18 cell-derived tumors in castrated mice was impaired when treated with the anti-GR agent mifepristone. In experiments with C4-2/C4-2R26 cell sets, GR activation in C4-2R26 cells increased their metastatic potential.

CONCLUSION

GR activation in radioresistant cells mediates androgen independence and facilitates PCa progression.

Development and validation of a patient decision aid for prostate Cancer therapy: from paternalistic towards participative shared decision making

BACKGROUND

Patient decision aids (PDAs) can support the treatment decision making process and empower patients to take a proactive role in their treatment pathway while using a shared decision-making (SDM) approach making participatory medicine possible. The aim of this study was to develop a PDA for prostate cancer that is accurate and user-friendly.

METHODS

We followed a user-centered design process consisting of five rounds of semi-structured interviews and usability surveys with topics such as informational/decisional needs of users and requirements for PDAs. Our user-base consisted of 8 urologists, 4 radiation oncologists, 2 oncology nurses, 8 general practitioners, 19 former prostate cancer patients, 4 usability experts and 11 healthy volunteers.

RESULTS

Informational needs for patients centered on three key factors: treatment experience, post-treatment quality of life, and the impact of side effects. Patients and clinicians valued a PDA that presents balanced information on these factors through simple understandable language and visual aids. Usability questionnaires revealed that patients were more satisfied overall with the PDA than clinicians; however, both groups had concerns that the PDA might lengthen consultation times (42 and 41%, respectively). The PDA is accessible on http://beslissamen.nl/ .

CONCLUSIONS

User-centered design provided valuable insights into PDA requirements but challenges in integrating diverse perspectives as clinicians focus on clinical outcomes while patients also consider quality of life. Nevertheless, it is crucial to involve a broad base of clinical users in order to better understand the decision-making process and to develop a PDA that is accurate, usable, and acceptable.

Radiation-induced glucocorticoid receptor promotes CD44+ prostate cancer stem cell growth through activation of SGK1-Wnt/β-catenin signaling

We observed cancer stem cell (CSC) population increase in radioresistant LNCaP (LNCaPR18) and C4-2 (C4-2R26) prostate cancer (PCa) cells compared with respective parental cells. Since the CD44 level increase was most significant in radioresistant PCa cells compared with parental cells among CSC markers tested, we isolated the CD44+ population from LNCaP/LNCaPR18 and C4-2/C4-2R26 cell sets via the immunomagnetic separation method and used them as CSC sources. We detected lower AR level, but higher glucocorticoid receptor (GR) level in CD44+ CSCs than CD44- non-CSCs. Higher GR level in CD44+ CSCs than CD44- cells was also detected when cells were isolated from mouse tumor tissues of LNCaPR18 cell and C4-2R26 cell-derived human xenografts and grown in culture. We then found blocking the GR signaling by adding the anti-GR agent mifepristone into the cell culture inhibited the CD44+ CSC growth while the addition of the anti-AR agent enzalutamide enhanced the CSC growth. In xenograft mouse studies in which tumors were developed from the injection of CD44+ CSCs of LNCaPR18 or C4-2R26 cell lines, retarded tumor growth in mifepristone-injected mice was observed compared with vehicle-treated mice. We next discovered the GR regulation of Wnt/β-catenin signaling pathway. We further found that the serum/glucocorticoid regulated kinase 1 (SGK1) is the GR downstream molecule that mediates Wnt/β-catenin signaling activation. Therefore, inhibition of either SGK1 or Wnt/β-catenin signaling impaired the in vitro CD44+ CSC growth. From these results, we suggest that blocking GR signaling or its downstream SGK1-Wnt/β-catenin signaling axis may suppress the radiation-induced CSC increase in PCa. KEY MESSAGES: Higher CSC population exists in radioresistant PCa cells than parental cells. Higher GR levels (and lower AR level) in CD44+ CSCs than CD44- non-CSCs. Use of anti-GR agent blocked the growth of CD44+ CSCs in in vitro/in vivo tests. GR downstream SGK1-Wnt/β-catenin signaling axis mediates the CSC increase. Targeting this signaling axis may enhance the radiotherapy efficacy in treating PCa.

Decision Support Systems in Prostate Cancer Treatment: An Overview

Background

A multifactorial decision support system (mDSS) is a tool designed to improve the clinical decision-making process, while using clinical inputs for an individual patient to generate case-specific advice. The study provides an overview of the literature to analyze current available mDSS focused on prostate cancer (PCa), in order to better understand the availability of decision support tools as well as where the current literature is lacking.

Methods

We performed a MEDLINE literature search in July 2018. We divided the included studies into different sections: diagnostic, which aids in detection or staging of PCa; treatment, supporting the decision between treatment modalities; and patient, which focusses on informing the patient. We manually screened and excluded studies that did not contain an mDSS concerning prostate cancer and study proposals.

Results

Our search resulted in twelve diagnostic mDSS; six treatment mDSS; two patient mDSS; and eight papers that could improve mDSS.

Conclusions

Diagnosis mDSS is well represented in the literature as well as treatment mDSS considering external-beam radiotherapy; however, there is a lack of mDSS for other treatment modalities. The development of patient decision aids is a new field of research, and few successes have been made for PCa patients. These tools can improve personalized medicine but need to overcome a number of difficulties to be successful and require more research.

Resveratrol treatment may preserve the erectile function after radiotherapy by restoring antioxidant defence mechanisms, SIRT1 and NOS protein expressions

Radiotherapy (RT) for prostate cancer (PC) can cause erectile dysfunction (ED) by damaging neurovascular structures with oxidative stress. In this study, we evaluated the effects of resveratrol, an antioxidant, on post-RT ED. Fifty rats in five groups were evaluated; control (C), prostate-confined radiotherapy with short- and long-term vehicle or resveratrol treatment. Cavernosal tissues were obtained to analyze glutathione (GSH), nitric oxide (NO), cyclic guanosine monophosphate (cGMP), 8-hydroxy-2'-deoxy-guanosine (8-OHdG) levels and superoxide dismutase (SOD), caspase-3 activities, sirtuin-1, Foxo-3, nNOS, and eNOS protein expressions. Intracavernosal pressures (ICP) were measured for the long-term treatment group. In the RT + long-term vehicle treatment group, tissue GSH, NO, cGMP, and SOD activity were decreased while 8-OHdg levels and caspase-3 activities were increased. Radiotherapy caused a decrease in sirtuin-1, nNOS, and eNOS protein expressions. These parameters were reversed by resveratrol treatment. Foxo-3 protein expressions were unaltered in the RT + short-term vehicle treatment group and started to increase as a defense mechanism in the RT + long-term vehicle group; however, resveratrol treatment caused a significant increase in Foxo-3 expressions. Resveratrol preserved the metabolic pathways involved in erectile function and provided functional protection. Resveratrol can be used as a supplementary agent in patients undergoing radiotherapy to preserve erectile function.

Risk Analysis of Prostate Cancer Treatments in Promoting Metabolic Syndrome Development and the Influence of Increased Metabolic Syndrome on Prostate Cancer Therapeutic Outcome

In clinical practice, few prostate cancer (PCa) patients are associated with metabolic syndrome (MetS), while few others acquire MetS during treatment. Whether the treatment of PCa increases the occurrence of MetS remains to be confirmed. This study reviewed the changes in MetS patients before and after PCa treatment to evaluate the effects of various treatment methods on MetS. We analyzed data of 1162 PCa patients, whether or not diagnosed with MetS, and changes in MetS patients after PCa treatment. Data of lower urinary tract symptoms, C-reactive protein (CRP), platelet distribution width (PDW), prostate-specific antigen (PSA), Gleason score, clinical stage, treatment methods, and progressive incidents were evaluated using logistic regression according to MetS diagnosis. The results showed significant differences in the prevalence of MetS before (17.38%) and after (23.67%) PCa treatment (P < 0.001). Bad diet, living habits, and prostate cancer treatment were considered as risk factors for MetS (OR = 1.731, 95%CI 1.367-2.193, P < 0.001). Radical prostatectomy (RP), androgen deprivation therapy including surgical castration and medical castration, iodine-125 seed brachytherapy (¹²⁵I limited), and chemotherapy were independent risk factors of MetS. The MetS incidence rates after treatment in ADT+¹²⁵I limited+chemotherapy compared to RP+TURP+EBRT were statistically significant at the corresponding risk grade (all P < 0.001). After treatment, the occurrence rates of progressive incidences were higher in MetS-PCa patients compared to non-MetS-PCa patients (all P < 0.001). So, the findings suggested that among PCa patients, multiple factors contribute to the occurrence of MetS, and PCa treatment is one among them. ADT+¹²⁵I limited+chemotherapy may be the most influential treatment for MetS.

Automated patient-specific transperineal ultrasound probe setups for prostate cancer patients undergoing radiotherapy

PURPOSE

The use of ultrasound imaging is not widespread in prostate cancer radiotherapy workflows, despite several advantages (eg, allowing real-time volumetric organ tracking). This can be partially attributed to the need for a trained operator during acquisition and interpretation of the images. We introduce and evaluate an algorithm that can propose a patient-specific transperineal ultrasound probe setup, based on a CT scan and anatomical structure delineations. The use of this setup during the simulation and treatment stage could improve usability of ultrasound imaging for relatively untrained operators (radiotherapists with less than 1 yr experience with ultrasound).

METHODS

The internal perineum boundaries of three prostate cancer patients were identified based on bone masks extracted from their CT scans. After projection of these boundaries to the skin and exclusion of specific areas, this resulted in a skin area accessible for transperineal ultrasound probe placement in clinical practice. Several possible probe setups on this area were proposed by the algorithm and the optimal setup was automatically selected. In the end, this optimal setup was evaluated based on a comparison with a corresponding transperineal ultrasound volume acquired by a radiation oncologist.

RESULTS

The algorithm-proposed setups allowed visualization of 100% of the clinically required anatomical structures, including the whole prostate and seminal vesicles, as well as the adjacent edges of the bladder and rectum. In addition, these setups allowed visualization of 94% of the anatomical structures, which were also visualized by the physician during the acquisition of an actual ultrasound volume.

CONCLUSION

Provided that the ultrasound probe setup proposed by the algorithm, is properly reproduced on the patient, it allows visualization of all clinically required structures for image guided radiotherapy purposes. Future work should validate these results on a patient population and optimize the workflow to enable a relatively untrained operator to perform the procedure.

A biodegradable rectal balloon implant to protect the rectum during prostate cancer radiotherapy for a patient with active Crohn's disease

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Active inflammatory bowel disease is an exclusion criterion for high-dose radiotherapy.

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A rectum spacer was inserted between the prostate and the rectal wall.

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The rectum spacer pushes the rectum outside of the high-dose area.

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No rectal toxicity of the radiotherapy or toxicity flare of the IBD was observed.

Background

Radiotherapy in patients with active inflammatory bowel disease (IBD) is usually considered an absolute exclusion criterion for prostate cancer radiotherapy treatment.

There are no reports available on the use of a biodegradable rectal balloon implantation (RBI) in patients with active IBD for prostate cancer radiotherapy.

Case presentation

We report on a patient with high-risk prostate cancer with the comorbidity of an active IBD with pancolitis location. He was treated with neo-adjuvant hormonal therapy and high-dose external beam radiotherapy to the prostate and the seminal vesicles. Before radiotherapy treatment, a biodegradable RBI was implanted between the prostate and the anterior rectal wall to push the rectum outside of the high-dose area. This patient at high-risk for rectal toxicity was successfully irradiated to his prostate with only a grade I urinary toxicity, no acute rectal toxicity or toxicity flare of the IBD.

Conclusions

This case describes the use of a RBI implantation in patients with active IBD for prostate cancer radiotherapy. The use of a biodegradable RBI proved to be a promised solution for such patients, and have to be further investigated.

Implantation of a biodegradable rectum balloon implant: tips, Tricks and Pitfalls

Introduction:

A rectum balloon implant (RBI) is a new device to spare rectal structures during prostate cancer radiotherapy. The theoretical advantages of a RBI are to reduce the high radiation dose to the anterior rectum wall, the possibility of a post-implant correction, and their predetermined shape with consequent predictable position.

Objective:

To describe, step-by-step, our mini-invasive technique for hands-free transperineal implantation of a RBI before start of radiotherapy treatment.

Materials and Methods:

We provide step-by-step instructions for optimization of the transperineal implantation procedure performed by urologists and/or radiation oncologists experienced with prostate brachytherapy and the use of the real-time bi-plane transrectal ultrasonography (TRUS) probe. A RBI was performed in 15 patients with localised prostate cancer. Perioperative side-effects were reported.

Results:

We provide ‘tips and tricks’ for optimizing the procedure and proper positioning of the RBI. Please watch the animation, see video in https://vimeo.com/205852376/789df4fae4.

The side-effects included mild discomfort to slight pain at the perineal region in 8 out of 15 patients. Seven patients (47%) had no complaints at all. Two patients developed redness of the skin, where prompt antibiotic regimen was started with no further sequelae. One patient revealed a temporary urine retention, which resolved in a few hours following conservative treatment. Further no perioperative complications occurred.

Conclusion:

This paper describes in detail the implantation procedure for an RBI. It is a feasible, safe and very well-tolerated procedure.

Exploiting Radiation-Induced Signaling to Increase the Susceptibility of Resistant Cancer Cells to Targeted Drugs: AKT and mTOR Inhibitors as an Example

Implementing targeted drug therapy in radio-oncologic treatment regimens has greatly improved the outcome of cancer patients. However, the efficacy of molecular targeted drugs such as inhibitory antibodies or small molecule inhibitors essentially depends on target expression and activity, which both can change during the course of treatment. Radiotherapy has previously been shown to activate prosurvival pathways, which can help tumor cells to adapt and thereby survive treatment. Therefore, we aimed to identify changes in signaling induced by radiation and evaluate the potential of targeting these changes with small molecules to increase the therapeutic efficacy on cancer cell survival. Analysis of "The Cancer Genome Atlas" database disclosed a significant overexpression of AKT1, AKT2, and MTOR genes in human prostate cancer samples compared with normal prostate gland tissue. Multifractionated radiation of three-dimensional-cultured prostate cancer cell lines with a dose of 2 Gy/day as a clinically relevant schedule resulted in an increased protein phosphorylation and enhanced protein-protein interaction between AKT and mTOR, whereas gene expression of AKT, MTOR, and related kinases was not altered by radiation. Similar results were found in a xenograft model of prostate cancer. Pharmacologic inhibition of mTOR/AKT signaling after activation by multifractionated radiation was more effective than treatment prior to radiotherapy. Taken together, our findings provide a proof-of-concept that targeting signaling molecules after activation by radiotherapy may be a novel and promising treatment strategy for cancers treated with multifractionated radiation regimens such as prostate cancer to increase the sensitivity of tumor cells to molecular targeted drugs. Mol Cancer Ther; 17(2); 355-67. ©2017 AACRSee all articles in this MCT Focus section, "Developmental Therapeutics in Radiation Oncology."

The Use of Ultrasound Imaging in the External Beam Radiotherapy Workflow of Prostate Cancer Patients

External beam radiotherapy (EBRT) is one of the curative treatment options for prostate cancer patients. The aim of this treatment option is to irradiate tumor tissue, while sparing normal tissue as much as possible. Frequent imaging during the course of the treatment (image guided radiotherapy) allows for determination of the location and shape of the prostate (target) and of the organs at risk. This information is used to increase accuracy in radiation dose delivery resulting in better tumor control and lower toxicity. Ultrasound imaging is harmless for the patient, it is cost-effective, and it allows for real-time volumetric organ tracking. For these reasons, it is an ideal technique for image guidance during EBRT workflows. Review papers have been published in which the use of ultrasound imaging in EBRT workflows for different cancer sites (prostate, breast, etc.) was extensively covered. This new review paper aims at providing the readers with an update on the current status for prostate cancer ultrasound guided EBRT treatments.

Atorvastatin enhances radiosensitivity in hypoxia-induced prostate cancer cells related with HIF-1α inhibition

Hypoxia could enhance radioresistance in prostate cancer cells through up-regulating HIF-1α, which could be inhibited by statins in several cancer cells. However, this effect of statins in prostate cancer remains unclear. In the present study, we aim to investigate the effect of atorvastatin on HIF-1α expression and radiosensitivity in prostate cancer cells. The hypoxia-induced human prostate cancer PC3 cells were generated by incubating with 5% O₂ for 24 h. The cell viability and apoptosis were respectively analyzed by cell counting kit-8 (CCK-8) assay and flow cytometry. The HIF-1α protein expression was assessed by Western blotting. HIF-1α expression in PC3 cells was significantly increased after incubating with 5% O₂ for 24 h. The viability of hypoxia-induced PC3 cells was inhibited by a higher dose of irradiation than control cells. The viability of hypoxia-induced PC3 cells were inhibited by astorvastatin with a higher concentration than control cells. Astorvastatin reduced the HIF-1α protein expression in hypoxia-induced PC3 cells, and induced apoptosis of both control and hypoxia-induced cells with and without irradiation. Atorvastatin could enhance radiosensitivity in hypoxia-induced prostate cancer cells, which may be related with inhibition of HIF-1α protein.

Candida albicans Osteomyelitis Pubis: The Possible Pathogenic Role of Pelvic Irradiation

Radiation to the pelvis, mainly directed against either prostatic or gynecologic cancers, is burdened by a lot of complications. The genitourinary tract is most frequently involved, presenting with bladder irritation, incontinence, and fertility disorders. However, side effects of radiation can also affect the bone, usually causing an osteolytic process which deteriorates the bone structure and leads to fractures, avascular necrosis, and other pathological insults. Here, we describe a case of Candida albicans osteomyelitis of the pubic symphysis as late complication of pelvic radiotherapy performed against prostate cancer.