Leukotoxicity after moderately Hypofractionated radiotherapy versus conventionally fractionated dose escalated radiotherapy for localized prostate Cancer: a secondary analysis from a randomized study

Bone marrow sparing in prostate cancer patients treated with Post-operative pelvic nodal radiotherapy - A proton versus photon comparison

PURPOSE

Extending salvage radiotherapy to treat the pelvic lymph nodes (PLNRT) improves oncologic outcomes in prostate cancer (PCa). However, a larger treatment volume increases the extent of bone marrow (BM) exposure, which is associated with hematologic toxicity (HT). Given the potential long-term impact of BM dose in PCa, clinical studies on BM sparing (BMS) are warranted. Herein, we dosimetrically compared photon and proton plans for BMS.

MATERIALS AND METHODS

Treatment plans of 20 post-operative PCa patients treated with volumetric-modulated arc photon therapy (VMAT) PLNRT were retrospectively identified. Contours were added for the whole pelvis BM (WPBM) and BM sub-volumes: lumbar-sacral (LSBM), iliac (ILBM), and lower pelvis (LPBM). Three additional plans were created: VMAT_BMS, intensity-modulated proton therapy (IMPT), and IMPT_BMS. Normal tissue complication probabilities (NTCP) for grade >3 hematologic toxicity (HT3+) were calculated for the WPBM volumes.

RESULTS

Compared to the original VMAT plan, mean doses to all BM sub-volumes were statistically significantly lower for VMAT_BMS, IMPT, and IMPT_BMS resulting in average NTCP percentages of 20.5 ± 5.9, 10.7 ± 4.2, 6.1 ± 2.0, and 2.5 ± 0.6, respectively. IMPT_BMS had significantly lower low dose metrics (V300cGy-V2000cGy) for WPBM and sub-volumes except for LPBM V2000cGy compared to VMAT_BMS and ILBM V20Gy compared to IMPT. In most cases, V4000cGy and V5000cGy within ILBM and LSBM were significantly higher for IMPT plans compared to VMAT plans.

CONCLUSIONS

BMS plans are achievable with VMAT and IMPT without compromising target coverage or OARs constraints. IMPT plans were overall better at reducing mean and NTCP for HT3+ as well as low dose volumes to BM. However, IMPT had larger high dose volumes within LSBM and ILBM. Further studies are warranted to evaluate the clinical implications of these findings.

Acute Toxicity and Quality of Life in a Post-Prostatectomy Ablative Radiation Therapy (POPART) Multicentric Trial

BACKGROUND

The aim of this study was to investigate the feasibility of ultrahypofractionated radiotherapy to the prostate bed in patients with biochemical and/or clinical relapse following radical prostatectomy who were enrolled in the prospective, observational, multicentric POPART trial (NCT04831970).

METHODS

Patients with post-radical prostatectomy PSA levels of ≥0.1-2.0 ng/mL and/or local relapse at PSMA PET/CT or multiparametric MRI were treated with Linac-based SBRT on the prostate bed up to a total dose of 32.5 Gy in five fractions every other day (EQD2_1.5 = 74.2 Gy). Maximum acute toxicity was assessed using the Common Terminology Criteria for Adverse Events version 5 scale. International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF) and Prostate Cancer Index Composite for Clinical Practice (EPIC-CP) scores were assessed at baseline and during the follow-up.

RESULTS

From April 2021 to June 2022, thirty men with a median age of 72 years (range 55-82) were enrolled in three centers. The median PSA level before RT was 0.30 ng/mL (range 0.18-1.89 ng/mL). At 3 months post-treatment, no GI or ≥2 GU side effects were reported; three patients (10%) experienced Grade 1 GU toxicity. No changes in ICIQ-SF or in the urinary domains of EPIC-CP were observed, while a transient worsening was registered in the bowel domain. At the same time point, all but two patients, who progressed distantly, were found to be biochemically controlled with a median post-treatment PSA level of 0.07 ng/mL (range 0-0.48 ng/mL).

CONCLUSIONS

Our preliminary findings show that SBRT can be safely extended to the postoperative setting, without an increase in short-term toxicity or a significant decline in QoL. Long-term results are needed to confirm this strategy.

Modulation of Peripheral Immune Cell Subpopulations After RapidArc/Moderate Hypofractionated Radiotherapy for Localized Prostate Cancer: Findings and Comparison With 3D Conformal/Conventional Fractionation Treatment

Radiotherapy (RT) is an important therapeutic option in patients with localized prostate cancer (PC). Unfortunately, radiation treatment causes a decrease in peripheral lymphocytes and, consequently, influences the patients' immune status. Our aim was to study changes in peripheral blood immune cell subpopulations after RT and during 6 months' follow-up in 2 groups of PC patients irradiated with different techniques and dose fractions with curative intent. We also investigated the presence of correlation between immune cell modulation and genitourinary or gastrointestinal toxicity. We enrolled 44 patients treated with curative RT (RapidArc/hypofractionation regimen or 3D conformal/conventional fractionation) for localized PC. Total white blood cell (WBC), absolute lymphocyte counts (ALCs), and peripheral immune cell subpopulations were analyzed at baseline, at the end of RT, and 3 and 6 months after the end of RT. WBC and ALC greatly decreased at the end of RT with a trend to recover at 6 months' follow-up in the hypofractionation group but not in the conventional one. Furthermore, B, total T, T CD4+, T CD8+, and NK cell values dropped significantly in both groups at the end of RT, with a minor decrease detectable in the hypofractionation group for B, total T, and T CD4+ lymphocytes with respect to the other technique/fractionation group. Double-negative T (DNT), double-positive T (DPT), and NKT cells significantly decreased at the end of RT with a slight tendency to recover values during follow-up, particularly in the hypofractionation group. No correlation with genitourinary or gastrointestinal toxicity was found. In this study, we showed, for the first time, the effects of RapidArc/moderate hypofractionation RT on immune cell subsets in patients treated for localized PC. Due to the growing interest in minority T-cell subpopulations for immunotherapy, we also reported longitudinal monitoring of the effects of RT on DNT, DPT, and NKT, which was never studied before. Our preliminary data highlight the importance of considering the effects of different RT techniques/fractionation regimens on peripheral immune cells, in the era of RT and immunotherapy combination.

Dose estimation after a mixed field exposure: Radium-223 and intensity modulated radiotherapy

INTRODUCTION

Radium-223 dichloride ([²²³Ra]RaCl₂), a radiopharmaceutical that delivers α-particles to regions of bone metastatic disease, has been proven to improve overall survival of men with metastatic castration resistant prostate cancer (mCRPC). mCRPC patients enrolled on the ADRRAD clinical trial are treated with a mixed field exposure comprising radium-223 (²²³Ra) and intensity modulated radiotherapy (IMRT). While absorbed dose estimation is an important step in the characterisation of wider systemic radiation risks in nuclear medicine, uncertainties remain for novel radiopharmaceuticals such as ²²³Ra.

METHODS

24-Colour karyotyping was used to quantify the spectrum of chromosome aberrations in peripheral blood lymphocytes of ADRRAD patients at incremental times during their treatment. Dicentric equivalent frequencies were used in standard models for estimation of absorbed blood dose. To account for the mixed field nature of the treatment, existing models were used to determine the ratio of the component radiation types. Additionally, a new approach (M-FISH_LET), based on the ratio of cells containing damage consistent with high-LET exposure (complex chromosomal exchanges) and low-LET exposure (simple exchanges), was used as a pseudo ratio for ²²³Ra:IMRT dose.

RESULTS

Total IMRT estimated doses delivered to the blood after completion of mixed radiotherapy (after 37 IMRT fractions and two [²²³Ra]RaCl₂ injections) were in the range of 1.167 ± 0.092 and 2.148 ± 0.096 Gy (dose range across all models applied). By the last treatment cycle analysed in this study (four [²²³Ra]RaCl₂ injections), the total absorbed ²²³Ra dose to the blood was estimated to be between 0.024 ± 0.027 and 0.665 ± 0.080 Gy, depending on the model used. Differences between the models were observed, with the observed dose variance coming from inter-model as opposed to inter-patient differences. The M-FISH_LET model potentially overestimates the ²²³Ra absorbed blood dose by accounting for further PBL exposure in the vicinity of metastatic sites.

CONCLUSIONS

The models presented provide initial estimations of cumulative dose received during incremental IMRT fractions and [²²³Ra]RaCl₂ injections, which will enable improved understanding of the doses received by individual patients. While the M-FISH_LET method builds on a well-established technique for external exposures, further consideration is needed to evaluate this method and its use in assessing non-targeted exposure by ²²³Ra after its localization at bone metastatic sites.

The Impact of Pelvic Nodal Radiotherapy on Hematologic Toxicity: A Systematic Review with Focus on Leukopenia, Lymphopenia and Future Perspectives in Prostate Cancer Treatment

INTRODUCTION

Hematologic toxicity (HT), particularly leukopenia, is a common side-effect of oncologic treatments for pelvic malignancies. Pelvic nodal radiotherapy (PNRT) has been associated with HT development mainly through incidental bone marrow (BM) irradiation; however, several questions remain about the clinical impact of radiotherapy-related HT. Herein, we perform a systematic review of the available evidence on PNRT and HT.

MATERIALS AND METHODS

A comprehensive systematic literature search was performed through EMBASE. Hand searching and clinicaltrials.gov were also used.

RESULTS

While BM-related dose-volume parameters and BM-sparing techniques have been more thoroughly investigated in pelvic malignancies such as cervical, anal, and rectal cancers, the importance of BM as an organ-at-risk has received less attention in prostate cancer treatment.

CONCLUSIONS

We examined the available evidence regarding the impact of PNRT on HT, with a focus on prostate cancer treatment. We suggest that BM should be regarded as an organ-at-risk for patients undergoing PNRT.

Lack of Relevant Haemogram Changes During Percutaneous Radiotherapy of Localised Prostate Cancer

BACKGROUND/AIM

In percutaneous radiotherapy dose-distribution and volumetric-load of normal tissue varies in different radiation-techniques. Haematotoxicity may lead to deficiencies of the immune and blood system or to secondary malignancies. Therefore, regular blood-counts are carried out during fractionated radiotherapy. The aim was to investigate patient haemogram courses during radiotherapy of localised prostate-cancer treated with different radiation-techniques (n=3).

PATIENTS AND METHODS

In this prospective study, blood count changes were examined during fractionated radiotherapy (3D-conformal-RT/step-and-shoot-IMRT/helical-IMRT) on the prostate-region in localised prostate-cancer cases (n=50).

RESULTS

The whole patient group displayed a small but significant reduction in leukocytes. This reduction was higher in the two IMRT groups compared to the 3D-group but without any case of leukopenia. Haemoglobin- or thrombocyte-levels did not significantly change.

CONCLUSION

Regardless of the delivery mode used, localised fractionated irradiation of prostate region did not cause any clinically relevant haemogram changes in this study. These findings question the necessity of regular blood counts during fractionated radiotherapy of the prostate region for patients without any risk factors.

Highlighting the Potential for Chronic Stress to Minimize Therapeutic Responses to Radiotherapy through Increased Immunosuppression and Radiation Resistance

Ionizing radiation has been used in the treatment of cancer for more than 100 years. While often very effective, there is still a great effort in place to improve the efficacy of radiation therapy for controlling the progression and recurrence of tumors. Recent research has revealed the close interaction between nerves and tumor progression, especially nerves of the autonomic nervous system that are activated by a variety of stressful stimuli including anxiety, pain, sleep loss or depression, each of which is likely to be increased in cancer patients. A growing literature now points to a negative effect of chronic stressful stimuli in tumor progression. In this review article, we present data on the potential for adrenergic stress to influence the efficacy of radiation and in particular, its potential to influence the anti-tumor immune response, and the frequency of an "abscopal effect" or the shrinkage of tumors which are outside an irradiated field. We conclude that chronic stress can be a major impediment to more effective radiation therapy through mechanisms involving immunosuppression and increased resistance to radiation-induced tumor cell death. Overall, these data highlight the potential value of stress reduction strategies to improve the outcome of radiation therapy. At the same time, objective biomarkers that can accurately and objectively reflect the degree of stress in patients over prolonged periods of time, and whether it is influencing immunosuppression and radiation resistance, are also critically needed.

Impact of COVID-19 on Prostate Cancer Management: Guidelines for Urologists

CONTEXT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has resulted in a global health emergency, the like of which has never been seen before. Prostate cancer (PCa) services across the globe have been on hold due to changing medical and surgical priorities. There is also epidemiological evidence that PCa patients have increased incidence and mortality from SARS-CoV-2 infection due to gender differences, age, and higher propensity for risk factors (eg, respiratory disease, obesity, hypertension, and smoking status).

OBJECTIVE

To contribute to the emerging body of knowledge on the risks of SARS-CoV-2 infection to PCa patients and, in the face of PCa treatment delays, provide evidence-based recommendations for ongoing management of specific PCa patient groups.

EVIDENCE ACQUISITION

A literature search was performed using all sources (MEDLINE, EMBASE, ScienceDirect, Cochrane Libraries, and Web of Science) as well as the media to harness emerging data on the SARS-CoV-2 pandemic and its influence on PCa. Eligibility criteria were originality of data and relevance to PCa management. The authors note that during these unprecedented times, retrospective data are constantly being updated from multiple sources globally.

EVIDENCE SYNTHESIS

A total of 72 articles and data sources were found initially. Owing to repetition, lack of originality, or nonrelevance, six articles were rejected, leaving 23 retrospective studies, seven basic science research articles, 15 societal and journal guidelines, and 21 epidemiological data sources, from countries at different stages of SARS-CoV-2 pandemic. These were analyzed qualitatively to produce evidence-based guidelines for the management of PCa patients at different stages of the patient journey, with strategies to reduce the risk of viral spread.

CONCLUSIONS

PCa patients may have an increased risk of SARS-CoV-2 infection as well as morbidity and mortality if infected. Once appropriately triaged, and to reduce viral spread, PCa patients can have surveillance by telemedicine, and institute lifestyle changes and social quarantining measures. If risk stratification suggests that treatment should be planned, androgen deprivation therapy can be started, or potentially surgery or radiation therapy is possible on a case-by-case basis.

PATIENT SUMMARY

Prostate cancer patients can be followed up remotely until the severe acute respiratory syndrome coronavirus 2 pandemic resolves, but higher-risk cases may have treatment expedited to limit any negative impact on prostate cancer outcomes.