Prostate Radiotherapy in the Era of Advanced Imaging and Precision Medicine

MRI-guided radiotherapy in twenty fractions for localised prostate cancer; results from the MOMENTUM study

Background and purpose

MRI-guided radiotherapy (MRIgRT) offers multiple potential advantages over CT-guidance. This study examines the potential clinical benefits of MRIgRT for men with localised prostate cancer, in the setting of moderately hypofractionated radiotherapy. We evaluate two-year toxicity outcomes, early biochemical response and patient-reported outcomes (PRO), using data obtained from a multicentre international registry study, for the first group of patients with prostate cancer who underwent treatment on a 1.5 T MR-Linac.

Materials and methods

Patients who were enrolled within the MOMENTUM study and received radical treatment with 60 Gy in 20 fractions were identified. PSA levels and CTCAE version 5.0 toxicity data were measured at follow-up visits. Those patients who consented to PRO data collection also completed EQ-5D-5L, EORTC QLQ-C30 and EORTC QLQ-PR25 questionnaires.

Results

Between November 2018 and June 2022, 146 patients who had MRIgRT for localised prostate cancer on the 1.5 T MR-Linac were eligible for this study. Grade 2 and worse gastro-intestinal (GI) toxicity was reported in 3 % of patients at three months whilst grade 2 and worse genitourinary (GU) toxicity was 7 % at three months. There was a significant decrease in the median PSA at 12 months. The results from both the EQ-5D-5L data and EORTC global health status scale indicate a decline in the quality of life (QoL) during the first six months. The mean change in score for the EORTC scale showed a decrease of 11.4 points, which is considered clinically important. QoL improved back to baseline by 24 months. Worsening of hormonal symptoms in the first six months was reported with a return to baseline by 24 months and sexual activity in all men worsened in the first three months and returned to baseline at 12 months.

Conclusion

This study establishes the feasibility of online-MRIgRT for localised prostate on a 1.5 T MR-Linac with low rates of toxicity, similar to that published in the literature. However, the clinical benefits of MRIgRT over conventional radiotherapy in the setting of moderate hypofractionation is not evident. Further research will focus on the delivery of ultrahypofractionated regimens, where the potential advantages of MRIgRT for prostate cancer may become more discernible.

Genetic predictors of radiation-induced morbidity in prostate cancer patients

Cancer survivors often face adverse effects of treatment, which have a significant impact on morbidity and mortality. Normal-tissue side effects following radiotherapy (RT), as one of therapeutic modalities, are common and may seriously affect quality of life which is especially important in long-term prostate cancer (PC) survivors. Upgrading in our knowledge in radiation biology have led to the better understanding that genetics plays a significant role in determining a patient's predisposition to developing late RT toxicity, leading to the new field of research called "radiogenomics". With the evolution of DNA sequencing technologies and genomic analysis, radiogenomics made an appearance as a state-of-the-art science in the field of personalized medicine with the goal of detection the genetic determinants RT adverse reactions. A single-nucleotide polymorphism (SNPs) - based assay could be used to predict the risk of RT side effects along with clinical features and treatment factors. Several SNPs have been identified that are associated with late radiation-induced morbidity in PC patients. Most importantly, these SNPs make up genes expressed in the tissues that are likely at the root of these symptoms, including the bladder, rectum, and small intestine, which are most exposed in PC RT. Furthermore, genome-wide association studies are likely to lead to an increasing number of genetic polymorphisms that can predict long-term RT complications. Finally, radiogenomics attempts to predict which PC patients will show radiosensitivity, so that radiation oncologists, as well as surgeons, can change treatment accordingly in order to reduce side effects or increase the RT effectiveness.

Diagnostic Performance of [18F]Fluorocholine and [68Ga]Ga-PSMA PET/CT in Prostate Cancer: A Comparative Study

The current study endeavored to closely compare the detection rate of 68-Gallium labelled prostate-specific membrane antigen ([⁶⁸Ga]Ga-PSMA) versus [¹⁸F]Fluorocholine in men with prostate cancer (PC), to investigate the benefits and pitfalls of each modality in the setting of various patient characteristics. We retrospectively analyzed 29 biopsy-proven PC patients in two categories, staging and restaging, who underwent both scans within a maximum of 30 days of each other. Variables including patient demographics, prostate specific antigen (PSA) level, Gleason score, clinical course, and following treatments were recorded. The number and location of suspicious lesions as well as uptake values were noted. A total of 148 suspicious lesions were detected, of which 70.9% (105/148) were concordantly visualized in both imaging modalities. [⁶⁸Ga]Ga-PSMA positron emission tomography/computed tomography (PET/CT) revealed a higher number of metastatic lesions per patients (91% vs 78%). The mean of maximum standardized uptake value (SUV max) in concordant lesions was significantly higher in [⁶⁸Ga]Ga-PSMA compared to [¹⁸F]Fluorocholine PET/CT (14.6 ± 8.44 vs. 6.9 ± 3.4, p = 0.001). Discordant lesions were detected by both modalities, but more frequently by [⁶⁸Ga]Ga-PSMA PET/CT (20.3% in [⁶⁸Ga]Ga-PSMA versus 8.8% by [¹⁸F]Fluorocholine PET/CT). In patients with PSA levels below 1.0 ng/mL and <2.0 ng/mL, [¹⁸F]Fluorocholine PET/CT detection rate was half (57% and 55%, respectively) that of [⁶⁸Ga]Ga-PSMA PET/CT. Tumor, nodes and metastases (TNM) staging, and subsequently patient management, was only influenced in 4/29 patients (14%), particularly by [⁶⁸Ga]Ga-PSMA PET/CT with PSA values under 0.5 ng/mL. [⁶⁸Ga]Ga-PSMA PET/CT revealed superior diagnostic performance to [¹⁸F]Fluorocholine PET/CT in staging and restaging of PC patients, especially in cases with low PSA levels. However, in a few hormone resistant high-risk PC patients, [¹⁸F]Fluorocholine PET/CT may improve overall diagnostic accuracy.

Modular Synthesis of DOTA-Metal-Based PSMA-Targeted Imaging Agents for MRI and PET of Prostate Cancer

A practical, convergent synthesis of prostate-specific membrane antigen (PSMA) targeted imaging agents for MRI, PET, and SPECT of prostate cancer has been developed. In this approach, metals chelated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were placed on the side chains of lysine early in the synthesis to form imaging modules. These are coupled to targeting modules, in this case consisting of the PSMA-binding urea DCL, bonded to an activated linker. The modular approach to targeted molecular imaging agents (TMIAs) offers distinct advantages. By chelating the MRI contrast metal Gd early, it doubles as a protecting group for DOTA. Standard coupling and deprotection steps may be utilized to assemble the modules into peptides, and the need for tri-tert-butyl protection of DOTA requiring removal by strong acid is averted. This enables mild conjugation of the imaging module to a wide variety of targeting agents in the final step. It was further discovered that two labile metals, La3+ or Ce3+ , can be used as placeholders in DOTA during the synthesis, then transmetalated in mild acid by Cu2+ , Ga3+ , In3+ , and Y3+ , metals used in PET/SPECT. This enables the efficient synthesis of nonradioactive analogues of targeted molecular imaging agents that may be transported or stored until needed. A simple and mild two-step transmetalation, involving de-metalation in dilute acid, followed by rapid chelation of the radioactive metal, may be conveniently performed later at the clinic to provide the TMIAs for PET or SPECT.

Palliative radiotherapy to dominant symptomatic lesion in patients with hormone refractory prostate cancer (PRADO)

Background

This study was conducted to investigate a new short-course radiotherapy regimen for patients with metastatic hormone refractory prostate cancer (HRPC) presenting with a dominant debilitating symptom.

Methods / design

This is an international, multi-center single arm prospective feasibility study that aims to include 34 patients with HRPC and a dominant debilitating symptom. The dominant symptomatic lesion will receive 4 × 5 Gy of high-precision radiotherapy, and the most aggressive part of the lesion 4 × 7 Gy using a simultaneous integrated boost technique. Based on advanced magnetic resonance imaging (MRI), an apparent diffusion coefficient (ADC) map will be calculated for the lesion using diffusion weighted imaging sequences. The dominant symptomatic lesion (GTV1) is drawn manually using the information from T2w-MRI and computed tomography scans. The most aggressive part of the dominant lesion (GTV2) is defined by using the ADC map. An auxiliary volume is created including only voxels in the GTV1 that presents with ADC values below 1200 × 10^− 6 mm²/s. The most aggressive part is defined as voxels with an ADC value below the median ADC value. Primary endpoint is feasibility, i.e. proportion of patients who complete radiotherapy with ≥90% of the prescribed dose. Secondary endpoints include dominant symptom score, progression-free survival (freedom from symptoms), overall survival, acute toxicity, quality of life, change in ADC from baseline to end of treatment and 6 months following treatment.

Discussion

If this new radiotherapy regimen proves to be feasible, a prospective randomized phase II/III dose escalation study will be designed in order to improve the outcomes of palliative radiotherapy of symptomatic metastatic HRPC.

Study status

The study is ongoing and will be recruiting patients soon.

Trial registration

clinicaltrials.gov NCT03658434. Initially registered on 30th of July, 2018

Racial and Ethnic Trends in Prostate Cancer Incidence and Mortality in Philadelphia, PA: an Observational Study

BACKGROUND

To learn more about local prostate cancer (PCa) disparities, we conducted descriptive analyses of the role of race and age in PCa using the Pennsylvania Cancer Registry data for Philadelphia (2005-2014).

METHODS

We focused on the most prevalent race/ethnic groups: white (33%), black (44%), and Hispanic (9%). Outcomes included PCa rates, tumor stage, and tumor grade. Percent change was used to describe changes in age-adjusted incidence and mortality rates. Frequency tables and logistic regression models were used to describe trends in proportions of advanced PCa by race and time. Race-by-time interaction terms were retained in the models if statistically significant.

RESULTS

PCa incidence was highest for black men over time. Incidence rates declined over time for all race groups (- 28% for white men to - 38% for Hispanic men). PCa mortality rates declined in a less universal manner (- 5% for blacks to - 32% for whites). Each year, odds increased across all race groups for advanced tumor stage (4% each year among white and Hispanic men and 9% each year among black men) and for advanced tumor grade (4% each year among white and black men and 23% each year among Hispanic men). Among younger men, black men experienced significantly increased odds of advanced tumor stage each year (8%) and Hispanics experienced significantly increased odds of advanced tumor grade each year (30%).

CONCLUSIONS

Black men remain at highest PCa risk relative to other racial/ethnic groups in Philadelphia. Younger black and Hispanic men are at particular risk for advanced PCa at diagnosis.

Late toxicity of image-guided hypofractionated radiotherapy for prostate: non-randomized comparison with conventional fractionation

PURPOSE

To evaluate the incidence and predictors for late toxicity and tumor outcome after hypofractionated radiotherapy using three different image-guided radiotherapy (IGRT) systems (hypo-IGRT) compared with conventional fractionation without image guidance (non-IGRT).

METHODS AND MATERIALS

We compared the late rectal and urinary toxicity and outcome in 179 prostate cancer patients treated with hypo-IGRT (70.2 Gy/26 fractions) and 174 non-IGRT patients (80 Gy/40 fractions). Multivariate analysis was performed to define predictors for late toxicity. 5- and 8-year recurrence-free survival (RFS) and overall survival (OS) were analyzed.

RESULTS

Mean follow-up was 81 months for hypo-IGRT and 90 months for non-IGRT group. Mainly mild late toxicity was observed: Hypo-IGRT group experienced 65 rectal (30.9% G1/G2; 6.3% G3/G4) and 105 urinary events (56% G1/G2; 4% G3/G4). 5- and 8-year RFS rates were 87.5% and 86.8% (hypo-IGRT) versus 80.4% and 66.8% (non-IGRT). 5- and 8-year OS rates were 91.3% and 82.7% in hypo-IGRT and 92.2% and 84% in non-IGRT group. Multivariate analysis showed that hypo-IGRT is a predictor for late genitourinary toxicity, whereas hypo-IGRT, acute urinary toxicity and androgen deprivation therapy are predictors for late rectal toxicity. Advanced T stage and higher Gleason score (GS) were correlated with worse RFS.

CONCLUSIONS

A small increase in mild late toxicity, but not statistically significant increase in severe late toxicity in the hypo-IGRT group when compared with conventional non-IGRT group was observed. Our study confirmed that IGRT allows for safe moderate hypofractionation, offering a shorter overall treatment time, a good impact in terms of RFS and providing potentially more economic health care.

How Would MRI-targeted Prostate Biopsy Alter Radiation Therapy Approaches in Treating Prostate Cancer?

OBJECTIVE

To determine if magnetic resonance imaging (MRI)/ultrasound fusion-targeted prostate biopsy (TB) would lead to increased recommendations of aggressive radiotherapy treatments for higher risk prostate cancer compared to systematic biopsy (SB) results.

METHODS

Clinicopathologic data of 533 men who underwent both TB and SB from 2014 to 2017 was analyzed. TB was performed in addition to SB in patients with detection of MRI suspicious lesions. Three patient cohorts were established: (1) biopsy naïve (80/533, 15.0%), (2) active surveillance (185/533, 34.7%), and (3) prior negative biopsy (268/533, 50.3%). Cancer risk categorical criteria were established with recommended radiotherapy treatment for each. Variation of risk classification due to biopsy method for all patients and within each cohort was analyzed using either a chi-squared statistic or Fisher's exact test. McNemar's pairwise analyses were performed for all risk categories between TB and SB to assess the effects of TB on high-risk cancer identification and subsequent radiotherapy recommendations.

RESULTS

Number of patients within cancer risk categories (1. "No Cancer or Low-Risk"; 2. "More Favorable Intermediate-Risk"; 3. "Less Favorable Intermediate-Risk"; 4. "High-Risk") varied significantly based on TB and SB pathology among all patients combined (P <.0001), in cohort 2 (P = .0005), and in cohort 3 (P <0.0001). Further, among all patients, TB increased cancer risk classification and correspondingly would result in more aggressive radiotherapy recommendations: "No Cancer or Low-Risk" to "Less Favorable Intermediate-Risk" (30/343, P <0.0001) and "No Cancer or Low-Risk" to "High-Risk" (31/353, P <.0001).

CONCLUSION

Among men with prostate cancer, TB commonly led to reclassification to a higher risk group, which is accompanied by more aggressive radiotherapy treatment recommendations when compared with SB findings alone.

Personalising Prostate Radiotherapy in the Era of Precision Medicine: A Review

Prostate cancer continues to be the most commonly diagnosed cancer among Canadian men. The introduction of routine screening and advanced treatment options have allowed for a decrease in prostate cancer-related mortality, but outcomes following treatment continue to vary widely. In addition, the overtreatment of indolent prostate cancers causes unnecessary treatment toxicities and burdens health care systems. Accurate identification of patients who should undergo aggressive treatment, and those which should be managed more conservatively, needs to be implemented. More tumour and patient information is needed to stratify patients into low-, intermediate-, and high-risk groups to guide treatment options. This paper reviews the current literature on personalised prostate cancer management, including targeting tumour hypoxia, genomic and radiomic prognosticators, and radiobiological tumour targeting. A review of the current applications and future directions for the use of big data in radiation therapy is also presented. Prostate cancer management has a lot to gain from the implementation of personalised medicine into practice. Using specific tumour and patient characteristics to personalise prostate radiotherapy in the era of precision medicine will improve survival, decrease unnecessary toxicities, and minimise the heterogeneity of outcomes following treatment.

Recent advances in radiation oncology

Radiotherapy (RT) is very much a technology-driven treatment modality in the management of cancer. RT techniques have changed significantly over the past few decades, thanks to improvements in engineering and computing. We aim to highlight the recent developments in radiation oncology, focusing on the technological and biological advances. We will present state-of-the-art treatment techniques, employing photon beams, such as intensity-modulated RT, volumetric-modulated arc therapy, stereotactic body RT and adaptive RT, which make possible a highly tailored dose distribution with maximum normal tissue sparing. We will analyse all the steps involved in the treatment: imaging, delineation of the tumour and organs at risk, treatment planning and finally image-guidance for accurate tumour localisation before and during treatment delivery. Particular attention will be given to the crucial role that imaging plays throughout the entire process. In the case of adaptive RT, the precise identification of target volumes as well as the monitoring of tumour response/modification during the course of treatment is mainly based on multimodality imaging that integrates morphological, functional and metabolic information. Moreover, real-time imaging of the tumour is essential in breathing adaptive techniques to compensate for tumour motion due to respiration. Brief reference will be made to the recent spread of particle beam therapy, in particular to the use of protons, but also to the yet limited experience of using heavy particles such as carbon ions. Finally, we will analyse the latest biological advances in tumour targeting. Indeed, the effectiveness of RT has been improved not only by technological developments but also through the integration of radiobiological knowledge to produce more efficient and personalised treatment strategies.

A Potential Role for Green Tea as a Radiation Sensitizer for Prostate Cancer

Prostate cancer (PCa) is the most common non-cutaneous cancer in the United States. There is currently a lack of safe and effective radiosensitizers that can enhance the effectiveness of radiation treatment (RT) for Pca. Clonogenic assay, PCNA staining, Quick Cell Proliferation assay, TUNEL staining and caspase-3 activity assay were used to assess proliferation and apoptosis in DU145 Pca cells. RT-PCR/IHC were used to investigate the mechanisms. We found that the percentage of colonies, PCNA staining intensity, and the optical density value of DU145 cells were decreased (RT/GT vs. RT). TUNEL + cells and the relative caspase-3 activity were increased (RT/GT vs. RT). Compared to RT, the anti-proliferative effect of RT/GT correlated with increased expression of the anti-proliferative molecule p16. Compared to RT, the pro-apoptotic effect of RT/GT correlated with decreased expression of the anti-apoptotic molecule Bcl-2. GT enhances RT sensitivity of DU145 by inhibiting proliferation and promoting apoptosis.

DNA repair deregulation in discrete prostate cancer lesions identified on multi-parametric MRI and targeted by MRI/ultrasound fusion-guided biopsy

Prostate cancer is histologically and molecularly heterogeneous. Clinically significant disease is often driven by dominant intra-prostatic lesions (IPLs). Prostate cancers cluster into molecular phenotypes with substantial genetic heterogeneity making pathway-based molecular analysis appealing. MRI/ultrasound fusion biopsy provides a unique opportunity to characterize tumor biology of discrete lesions at diagnosis. This study determined the feasibility of pathway-based gene expression analysis of prostate biopsies and characterized cancer pathway deregulation.

Thirteen patients had prostate cancer diagnosed by MRI/ultrasound fusion biopsy and either Gleason 6 or Gleason ≥8. Gene expression profiling was performed on 14 biopsies using >700 genes representing 13 cancer pathways. Pathway-based analysis compared gene expression among samples based on clinical, pathological, and radiographic characteristics. Pathway-based gene expression analysis was successful in 12 of 14 (86%) samples. Samples clustered based upon deregulation of DNA Repair and Notch, Chromatin Modification and Cell Cycle, or all other pathways, respectively. DNA Repair demonstrated the greatest differential deregulation. Lesions with Gleason ≥8, PSA ≥10, or intense dynamic contrast enhancement (DCE) had significantly higher DNA Repair deregulation than those with Gleason 6, PSA <10, or low to moderate DCE. Alterations in DNA Repair gene expression were diverse with upregulation of markers of DNA damage and down-regulation of DNA Repair proteins. This study demonstrates the feasibility of pathway-level gene expression analysis of discrete intra-prostatic lesions sampled by MRI/ultrasound fusion biopsy. IPLs cluster into distinct molecular phenotypes, the most significantly altered being DNA Repair.

Implementing web-based ping-pong-type e-communication to enhance staff satisfaction, multidisciplinary cooperation, and clinical effectiveness: A SQUIRE-compliant quality-improving study

BACKGROUND

Frequent multidisciplinary communication is essential in conducting daily radiotherapy (RT) practice. However, traditional oral or paper-based communication has limitations. E-communication has been suggested, but its effects are still not well demarcated in the field of radiation oncology.

OBJECTS

In our web-based integrated information platform, we constructed a ping-pong-type e-communication function to transfer specific notations among multidisciplinary RT staffs. The purpose was to test whether applying this e-communication can increase effectiveness of multidisciplinary cooperation when compared with oral or paper-based practice. Staff satisfaction and clinical benefits were also demonstrated.

DESIGN AND SETTING

A real-world quality-improving study was conducted in a large center of radiation oncology.

PARTICIPANTS AND DATASET USED

Before and after applying multidisciplinary e-communication (from 2014 to 2015), clinical RT staffs were surveyed for their user experience and satisfaction (n = 23). For measuring clinical effectiveness, a secondary database of irradiated head and neck cancer patients was re-analyzed for comparing RT toxicities (n = 402).

INTERVENTIONS

Applying ping-pong-type multidisciplinary reflective e-communication was the main intervention.

OUTCOME MEASURES

For measuring staff satisfaction, eight domains were surveyed, such as timeliness, convenience, and completeness. For measuring clinical effectiveness of multidisciplinary cooperation, event rates of severe (i.e., grade 3-4) RT mucositis and dermatitis were recorded.

RESULTS

Overall, when compared with oral communication only, e-communication demonstrated multiple benefits, particularly on notation-review convenience (2.00 ± 1.76 vs 9.19 ± 0.81; P < 0.0001).When compared with paper-based practice, e-communication showed statistically significant benefits on all eight domains, especially on notation-review convenience (5.05 ± 2.11 vs 9.19 ± 0.81; P < 0.0001) and convenience of feedback notation (4.81 ± 1.72 vs 8.76 ± 1.09; P < 0.0001).Moreover, staff satisfaction was gradually increased from oral (3.57 ± 1.94), paper-based (5.57 ± 2.06), to e-communication (8.76 ± 0.70; P < 0.0001). Secondary measurement confirmed these observations.Before and after facilitating multidisciplinary cooperation by using e-communication, severe (i.e., grade 3-4) mucositis and dermatitis were decreased from 21.7% to 10% then to 5.1%.

CONCLUSIONS

Replacing oral or paper-based practice with e-communication is useful in facilitating RT multidisciplinary teamwork. Staff satisfaction and clinical effectiveness can be increased.

PSMA PET and Radionuclide Therapy in Prostate Cancer

Prostate cancer (PCa) is the most common malignancy in men and a major cause of cancer death. Accurate imaging plays an important role in diagnosis, staging, restaging, detection of biochemical recurrence, and for therapy of patients with PCa. Because no effective treatment is available for advanced PCa, there is an urgent need to develop new and more effective therapeutic strategies. To optimize treatment outcome, especially in high-risk patients with PCa, therapy for PCa is moving rapidly toward personalization. Medical imaging, including positron emission tomography (PET)/computed tomography (CT), plays an important role in personalized medicine in oncology. In the recent years, much focus has been on prostate-specific membrane antigen (PSMA) as a promising target for imaging and therapy with radionuclides, as it is upregulated in most PCa. In the prostate, one potential role for PSMA PET imaging is to help guide focal therapy. Several studies have shown great potential of PSMA PET/CT for initial staging, lymph node staging, and detection of recurrence of PCa, even at very low prostate-specific antigen values after primary therapy. Furthermore, studies have shown that PSMA PET/CT has a higher detection rate than choline PET/CT. Radiolabeled PSMA ligands for therapy show promise in several studies with metastatic PCa and is an area of active investigation. The "image and treat" strategy, with radiolabeled PSMA ligands, has the potential to improve the treatment outcome of patients with PCa and is paving the way for precision medicine in PCa. The aim of this review is to give an overview of recent advancement in PSMA PET and radionuclide therapy for PCa.