Hypofractionated radiotherapy versus conventional radiotherapy in patients with intermediate- to high-risk localized prostate cancer: a meta-analysis of randomized controlled trials

Interactions between radiotherapy resistance mechanisms and the tumor microenvironment

BACKGROUND

Resistance to radiotherapy (RT) presents a significant clinical challenge in management of cancer. Recent evidence points to specific mechanisms of resistance within the tumor microenvironment (TME), which we aim to discuss, with the aim of overcoming the clinical challenge.

METHODS

We performed the narrative review using PubMed and Web of Science databases to identify studies that reported the regulative network and treatments of RT resistance from TME perspectives.

RESULTS

RT significantly changes the immune TME of cancers, which is closely appearing to play a key role in RT resistance (RTR) by modulating immune cell infiltration and function. Various phenotypes are involved in the development of RTR, such as autophagy, senescence, oxidative stress, cell polarization, ceramide metabolism, and angiogenesis in the TME. Key genes and pathways are also implicated in RTR, including immune and inflammatory cytokines, TGF-β, P53, the NF-κB pathway, the cGAS/STING pathway, the ERK and AKT pathway, and the STAT pathway. Based on the mechanism of RTR in the TME, many proposed routes to overcome RTR, several specifically target the TME including targeting fibroblast activation protein, exosomes management, nanomedicine, and immunotherapy. Many challenges in RT resistance still need to be further explored with emerging investigative methods, such as artificial intelligence, genetic technologies, and bioengineering.

CONCLUSIONS

The complex interactions between RT and TME significantly affect the efficiency of RT. Novel approaches to overcome this clinical difficulty are promising, which needs future work to further explore and identify better treatment strategies.

Prospective Observational Study on Moderate Hypofractionated Radiotherapy for Localized Prostate Cancer in Rwanda: Acute Toxicity in Patients

PURPOSE

Moderate hypofractionation (MHF) offers logistical and financial advantages, and has become standard in Western countries but not yet in Africa. This study assessed GI and genitourinary (GU) acute toxicity in Rwandan men undergoing MHF (20 × 3 Gy) treatment.

MATERIALS AND METHODS

Since 2021, patients with prostate cancer at the Rwanda Cancer Centre have been informed about the study on MHF treatment and could participate by signing an informed consent. The study included patients with confirmed prostate adenocarcinoma (any T, any prostate-specific antigen any Gleason score, N0M0), excluding those with inflammatory bowel disease, previous pelvic irradiation, or previous prostatectomy. Participants received 20 fractions of 3 Gy over 4 weeks using the volumetric modulated arc radiotherapy (RT) technique with a 6 megavoltage linear accelerator. GI and GU acute toxicity was evaluated at week 2, at the end of RT, and 3 months after treatment using the Radiation Therapy Oncology Group (RTOG) acute toxicity grading system.

RESULTS

Fifty consecutive patients with localized prostate cancer were included. The median patient age was 70 years. Most patients (86%) had high-risk disease and 94% received androgen-deprivation therapy. The cost and treatment time were reduced by 50%. The distribution of maximum acute RTOG toxicity scores were for GI 10% grade 0, 70% grade 1, 20% grade 2, 0% grade 3, and for GU scores were 0%, 40%, 54%, and 6%, respectively. By 3 months, RT symptoms had returned to baseline levels for most patients.

CONCLUSION

MHF (20 × 3 Gy) was well tolerated in men treated for prostate cancer in Rwanda, showing that MHF is feasible in an African setting. However, further research on acute and late toxicity for more patients is warranted.

Hypofractionated versus conventional fractionation external beam radiotherapy in intermediate and high risk localized prostate cancer

BACKGROUND

Prostate cancer is the second most common malignancy in men, and its incidence is increasing which is attributed to increased screening programs. The treatment options of intermediate and high risk prostate cancer include radical prostatectomy, radiotherapy and androgen deprivation therapy. Hypofractionated radiotherapy is becoming more popular lately due to better understanding of the radiobiology of prostate cancer and favorable logistics.

OBJECTIVE

To compare the toxicity and efficacy of hypofractionated versus conventional fractionation external beam radiotherapy in patients with intermediate and high risk localized prostate cancer treated in Shaukat Khanum Memorial Hospital and Research Center, Lahore (SKMCH & RC).

METHODOLOGY

We retrospectively conducted this study on histopathologically confirmed 114 patients with prostate adenocarcinoma who underwent treatment from January 2013 till December 2018. These patients were treated with radical radiotherapy along with hormonal therapy as per indication. Data was collected from electronic hospital system and analyzed by SPSS version 23.

RESULTS

114 patients were selected according to the inclusion criteria. Mean age was 68 years (61-75). 88% of patients had stage III-IVA disease at the time of diagnosis. Mean PSA and GS was 33 ± 39 SD and 7 ± 0.9 SD respectively. 89% (n = 102) received radiotherapy with 69% of patients receiving dose of 60 Gy in 20 fractions. Among patients who received hypofractionated dose, 86% (n = 61) of them were categorized as high risk and 14% (n = 10) were intermediate risk, whereas among conventional group 90% (n = 28) were high risk patients and 10% (n = 3) were of intermediate risk. In hypofractionated dose group, 14% (n = 10) developed grade 2 proctitis and 8% (n = 6) developed grade 2 cystitis, in contrast to conventional dose group in which only 3 patients (5%) developed grade 2 GI toxicity and 2 patients (2.9%) had grade 2 GU toxicity. However, these toxicities and their grade were clinically insignificant when compared with the dose groups (p = 0.11). 5 year overall survival for hypofractionated radiotherapy versus conventional dose was 100% and 90% respectively with 95% Cl and p value of 0.3 (clinically insignificant), whereas 5 year disease free survival was 100% and 75% for hypofractionation versus conventional EBRT respectively with 95% CI and p value of 0.04 (clinically significant).

CONCLUSION

Hypofractionated radiotherapy in patients with intermediate and high risk localized prostate cancer has better disease free survival at the expense of higher risk for proctitis and cystitis but no difference in overall survival as compared to conventional dose of radiation.

Acute and late toxicity patterns of moderate hypo-fractionated radiotherapy for prostate cancer: a systematic review and meta-analysis

Introduction

Moderate hypofractionated (HF) radiotherapy is becoming the new standard in radiotherapy for prostate cancer patients. It is established as safe, but it might be associated with increased acute toxicity levels. We conducted a systematic review on moderate HF to establish acute toxicity levels and their required clinical management; late toxicity was reported as a secondary outcome.

Material and methods

Using PRISMA guidelines, we conducted a systematic review for studies published until June 2022. We identified 17 prospective studies, with 7796 localised prostate cancer patients, reporting acute toxicity of moderate hypofractionation (2.5-3.4 Gy/fraction). A meta-analysis was done for 10/17 studies with a control arm (standard fractionation (SF)), including evaluation of late toxicity rates. We used Cochrane bias assessment and Newcastle-Ottawa bias assessment tools for randomized controlled trials (RCTs) RCT and non-RCTs, respectively.

Results

Pooled results showed that acute grade ≥ 2 gastro-intestinal (GI) toxicity was increased by 6.3 % (95 % CI for risk difference = 2.0 %-10.6 %) for HF vs SF. Acute grade ≥ 2 Genito-urinary (GU) and late toxicity were not significantly increased. The overall risk of bias assessment revealed a low risk in the meta-analysis of included studies. Data on management of toxicity (medication, interventions) was only reported in 2/17 studies.

Conclusion

HF is associated with increased acute GI symptoms, needing adequate monitoring and management. Reports on toxicity management were very limited. Pooled late GI and GU toxicity showed similar levels for SF and HF.

Cost-effectiveness analysis of ultra-hypofractionated radiotherapy and conventionally fractionated radiotherapy for intermediate- to high-risk localized prostate cancer

Background

Radiotherapy is an effective curative treatment option for intermediate- to high-risk localized prostate cancer. According to the HYPO-RT-PC trial (ISRCTN45905321), there was no significant difference in 5 years of follow-up in terms of failure-free survival, overall survival, urinary toxicity, and bowel toxicity, while erectile function decreased between ultra-hypofractionated radiotherapy with conventionally fractionated radiotherapy, except that the incidence of urinary toxicity in ultra-hypofractionated radiotherapy was higher at 1 year of follow-up. We evaluated the cost-effectiveness of ultra-hypofractionated radiotherapy and conventionally fractionated radiotherapy for intermediate- to high-risk localized prostate cancer from the Chinese payer's perspective.

Methods

We developed a Markov model with a 15-year time horizon to compare the cost and effectiveness of ultra-hypofractionated radiotherapy with those of conventionally fractionated radiotherapy for localized intermediate- to high-risk prostate cancer. The outcomes were measured in quality-adjusted life-years (QALYs), incremental cost-effectiveness ratio (ICER), and willingness-to-pay (WTP). Univariable and probability sensitivity analyses were performed to evaluate the robustness of the Markov model.

Results

Based on the Markov model, conventionally fractionated radiotherapy yielded 2.32 QALYs compared with 2.14 QALYs in ultra-hypofractionated radiotherapy in China. The cost of ultra-hypofractionated radiotherapy was found to be decreased by about 14% folds ($4,251.04) in comparison with that of conventionally fractionated radiotherapy. The ICER of conventionally fractionated radiotherapy versus that of ultra-hypofractionated radiotherapy was $23,616.89 per QALY in China. The failure-free survival with grade 2 or worse urinary toxicity and the discount rate per annum were the most sensitive parameters utilized in ultra-hypofractionated radiotherapy. The cost-effectiveness acceptability curve showed that conventionally fractionated radiotherapy had 57.7% probability of being cost-effective under the Chinese WTP threshold.

Conclusion

From the perspective of Chinese payers, ultra-hypofractionated radiotherapy was not a cost-effective strategy compared with conventionally fractionated radiotherapy for patients with localized intermediate- to high-risk prostate cancer. Nevertheless, reduction of the grade 2 or worse urinary toxicity of ultra-hypofractionated radiotherapy could alter the results.

Bowel and bladder reproducibility in image guided radiation therapy for prostate cancer: Results of a patterns of practice survey

Purpose

Optimal management of patients with prostate cancer (PCa) to achieve bowel and bladder reproducibility for radiation therapy (RT) and the appropriate planning target volume (PTV) expansions for use with modern image guidance is uncertain. We surveyed American Society of Radiation Oncology radiation oncologists to ascertain practice patterns for definitive PCa RT with respect to patient instructions and set up, daily image guidance, and subsequent PTV expansions.

Methods and Materials

A pattern of practice survey was sent to American Society of Radiation Oncology radiation oncologists who self-identified as specializing in PCa. Respondents identified the fractionation regimens routinely used, and their practices regarding diet, bowel, and bladder instructions for patients with PCa before RT simulation and throughout treatment. Questions regarding PTV margins, daily set up practices, and use of image guidance were included.

Results

Of 190 respondents, 158 reported using conventional fractionation (CFx), 49 moderate hypofractionation (MHFx), and 61 stereotactic body radiation therapy (SBRT). Diet modifications during RT were advised by 84% of respondents, treatment with full bladder by 96%, and bowel instructions by 78%. Prescription of bowel medication was higher for respondents using SBRT (95.1%) versus those using CFx/MHFx (55.1%; 34.7%). The most common implantable device reported was fiducial markers, with increased use in SBRT (86.0%; 68.9%) versus CFx/MHFx. Cone beam computed tomography was the most common daily imaging technique across fractionation regimens. SBRT showed correlation between PTV margin expansions, fiducial marker use, and image guidance.

Conclusions

Survey results indicate heterogeneity in treatment modality, dose, patient instructions, and PTV expansions used by radiation oncologists in the treatment of patients with PCa. Further investigation to define appropriate patient instructions on bowel preparation to maximize target reproducibility in PCa is needed, as is continued guidance on evidence-based approaches for image guidance and PTV margin selection.

Epigenetic mechanisms underlying prostate cancer radioresistance

Radiotherapy (RT) is one of the mainstay treatments for prostate cancer (PCa), a highly prevalent neoplasm among males worldwide. About 30% of newly diagnosed PCa patients receive RT with a curative intent. However, biochemical relapse occurs in 20–40% of advanced PCa treated with RT either alone or in combination with adjuvant-hormonal therapy. Epigenetic alterations, frequently associated with molecular variations in PCa, contribute to the acquisition of a radioresistant phenotype. Increased DNA damage repair and cell cycle deregulation decreases radio-response in PCa patients. Moreover, the interplay between epigenome and cell growth pathways is extensively described in published literature. Importantly, as the clinical pattern of PCa ranges from an indolent tumor to an aggressive disease, discovering specific targetable epigenetic molecules able to overcome and predict PCa radioresistance is urgently needed. Currently, histone-deacetylase and DNA-methyltransferase inhibitors are the most studied classes of chromatin-modifying drugs (so-called ‘epidrugs’) within cancer radiosensitization context. Nonetheless, the lack of reliable validation trials is a foremost drawback. This review summarizes the major epigenetically induced changes in radioresistant-like PCa cells and describes recently reported targeted epigenetic therapies in pre-clinical and clinical settings.

Hypofractionated radiotherapy versus conventional radiotherapy for diffuse intrinsic pontine glioma: A systematic review and meta-analysis

BACKGROUND

The standard treatment for diffuse intrinsic pontine glioma (DIPG) is radiotherapy, although conventional fractionated radiotherapy (CFRT) may not be in the best interest of the patient. Instead, hypofractionated radiotherapy (HFRT) may shorten the treatment period and reduce related costs for this treatment, which is typically palliative in nature.

METHODS

This systematic review and meta-analysis evaluated survival outcomes among patients who received HFRT or CFRT for DIPG. The PubMed, Medline, EMBASE, Cochrane Central Register, and Scopus databases were searched to identify relevant studies. Overall survival was the primary outcome of interest and progression-free survival was the secondary outcome of interest.

RESULTS

The search identified a total of 2376 reports, although only 4 reports were ultimately included in the meta-analysis. The studies included 88 patients who underwent HFRT and 96 patients who underwent CFRT. Relative to CFRT, HFRT provided comparable outcomes in terms of overall survival (hazard ratio [HR]: 1.07, 95% confidence interval [CI]: 0.77-1.47) and progression-free survival (HR: 1.04, 95% CI: 0.75-1.45).

CONCLUSIONS

The results of this meta-analysis suggest that CFRT and HFRT provide similar survival outcomes for patients with DIPG.

Comparison of Survival Between Hypofractionated and Conventional Radiotherapy in Clinically Localized Prostate Cancer: A Single-Center Retrospective Cohort

Background: Prostate cancer (pCa) is the most frequently diagnosed visceral cancer among men. The main role of radical prostatectomy and external-beam radiation therapy (EBRT) in the management of patients with localized pCa has been established. Objectives: This study aims at comparing the clinical outcomes of hypofractionated versus conventional EBRT in the definitive management of patients with localized pCa. Methods: From 2013 to 2019, a consecutive series of patients with localized pCa was treated with conventional (74 Gy at 2 Gy fractions) or hypofractionated (70.2 Gy at 2.7 Gy fractions) radiotherapy schedules, using 3-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), respectively. The impact of the fractionation schedule on biochemical or clinical relapse-free survival (bc-RFS) and overall survival (OS) was assessed. Results: The median follow-up was 42 months (range: 8 - 81 months). Among 170 patients, 81 were treated with conventional and 89 with the hypofractionated schedule. The patient characteristics between groups were comparable. The mean bc-RFS of patients in conventional and hypofractionated groups was 34.9 and 35.4 months, respectively (confidence interval (CI) 95%: 34.5 - 35.7, P = 0.25). Accordingly, the mean OS of patients in conventional and hypofractionated groups was 34.6 and 38.6 months, respectively (CI 95%: 37.3 - 38.6, P = 0.04). The sub-analysis showed that the OS benefit of hypofractionated schedule was limited to intermediate- and high-risk groups with a trend toward significance (CI 95%: 0.02 - 1.46, P = 0.054). Conclusions: Hypofractionation had OS benefit over the conventional schedule for definitive radiotherapy of localized pCa. This benefit was limited to patients with intermediate- and high-risk pCa.