Defining Oligometastatic Disease in the New Era of PSMA-PET Imaging for Primary Staging of Prostate Cancer

Oncological Outcomes in Patients with Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography-detected Oligometastatic Prostate Cancer Treated with Metastasis-directed Radiotherapy as the Single Treatment Modality

BACKGROUND AND OBJECTIVE

In patients with biochemical recurrence (BCR), prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) can detect oligometastatic prostate cancer (PCa). However, the optimal treatment approach for oligometastatic disease remains unclear. This study aims to assess the oncological outcomes of metachronous oligometastatic PCa patients treated with metastasis-directed radiotherapy (MDRT).

METHODS

We retrospectively evaluated patients with hormone-sensitive, metachronous oligometastatic PCa who underwent MDRT for BCR (from July 2012 to September 2022). Patients had one to four lymph nodes and/or bone metastases on PSMA PET/CT and were irradiated with 5 × 7 or 3 × 10 Gy. The biochemical response to MDRT was assessed as undetectable prostate-specific antigen (PSA) at follow-up, PSA response (PSA ≤ pretreatment level), or biochemical progression (PSA > pretreatment level). Biochemical progression-free survival (bPFS) and local remission of disease (absence of disease at the MDRT site on follow-up PSMA PET/CT or undetectable PSA) were evaluated.

KEY FINDINGS AND LIMITATIONS

Eighty patients underwent MDRT for 105 PSMA PET/CT-confirmed lesions. The median time from curative treatment to MDRT was 55 mo (interquartile range [IQR] 31-103). At a median follow-up of 32 mo after MDRT (IQR 21-64), 10% of the patients were PSA free, 10% had a PSA response, and 80% experienced biochemical progression. The bPFS rates at 1 and 2 yr were 54% and 38%, respectively. A total of 87% of patients had local control of disease after MDRT, whereas 72% had new metastatic lesions on repeated PSMA PET/CT. Limitations include the retrospective design and a small cohort.

CONCLUSIONS AND CLINICAL IMPLICATIONS

MDRT for oligometastatic disease shows high local efficacy. However, disease progression is observed in a substantial proportion of patients.

Stereotactic ablative radiotherapy (SABR) for pelvic nodal oligorecurrence in prostate cancer

Background

This study evaluated the clinical outcomes of stereotactic ablative radiotherapy (SABR) in the treatment of oligometastatic pelvic node prostate cancer to delay androgen deprivation therapy (ADT).

Materials and methods

Pelvic lymph node metastases were identified by 11C-choline positron emission tomography (PET)-computed tomography (CT), and patients were not receiving ADT. SABR was administered using linear accelerators with intensity-modulated and image-guided radiotherapy, at a prescribed dose of 35 Gy in 5 fractions over 2 weeks. Response was assessed using Response Evaluation Criteria in Solid Tumours (RECIST) v1.1 criteria, and prostate-specific antigen (PSA) levels were monitored post-SABR. Toxicity and quality of life were assessed by the Common Terminology Criteria for Adverse Events Toxicity (CTCAE) v.5.0 and European Organisation for Research and Treatment of Cancer (EORTC) quality of life questionnaires QLQ-C30/QLQ-PR25, respectively. Kaplan-Meier and T-test were used for statistical analysis.

Results

Between June 2015 and November 2023, 56 patients with 85 lesions were treated at our institution. Median follow-up was 30 months [95% confidence interval (CI): 24-33.6]. Prostatectomy was the radical treatment in 85.7% of patients, and radiotherapy in 14.3%. Response rates were 67.1% for complete response, 27.4% for partial response, and 1.4% for stable disease. In-field progression was observed in only 3 lesions (3.5%). The median time to biochemical relapse post-SABR was 15 months (95% CI: 11.4-18.6). Three-year pelvic nodal and distant progression-free survival were 62.5% and 80%, respectively. There was a significant decrease in PSA levels after SABR compared to pretreatment levels (0.77 vs. 2.16 ng/mL respectively, p = 0.001). No grade ≥ 2 genitourinary or gastrointestinal toxicities. The median global health status score was 83.33 points at both time points analysed.

Conclusion

SABR can delay the ADT and provide excellent local control while preserving quality of life.

Biochemical outcome in metastatic prostate cancer patients following prostate-directed radiotherapy

Background

The role of cytoreductive local radiotherapy (RT) in metastatic prostate cancer (mPCa) has recently been established. This study aimed to evaluate the biochemical outcome of local RT in mPCa.

Methods

This randomised controlled phase III study was conducted at the Clinical Oncology Department, Suez Canal University Hospital. Eligible participants were de-novo or metachronous mPCa patients with Eastern Cooperative Oncology Group performance status of 0-2. Participants were randomised to receive either cytoreductive prostate-directed RT in addition to standard care or standard care alone. The conventional radiation schedule of 70 Gy/35 fractions or the hypofractionated schedule of 55 Gy/20 fractions were delivered. The primary endpoint was biochemical progression-free survival (BPFS), and the secondary endpoint was overall survival (OS). Survival and post-hoc analyses were performed using Cox regression and the Kaplan-Meier method with the log-rank test.

Results

Between 23 November 2020 and 21 2022, 70 patients were enrolled in this study. Of them, 34 patients were assigned to the prostate RT group, and 29 patients were assigned to the control group. At a median follow-up of 12 months, the median BPFS has not been reached for the prostate RT group compared to 4.067 months for the control group (HR: 0.147, p < 0.001). Subgroup analysis showed that the median BPFS was statistically significantly correlated with low-volume (95% CI, 0.004 to 0.262, p = 0·001) and hormonal-sensitive metastatic disease (95% CI, 0.010 to 0.192, p < 0·001). The median OS was 16.33 months for the prostate-RT group compared to 11.33 months for the control group (HR: 0.313, p = 0.003).

Conclusion

Prostate-directed RT improved BPFS and OS in mPCa patients, particularly in those with low volume and hormonal-sensitive disease.

Trial Registration

This trial is registered on (27/4/2023), retrospectively registered with pactr.samrc.ac.za, PACTR202305854600529, URL: https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=25510.

Novel hormone therapy and coordination of care in high-risk biochemically recurrent prostate cancer

Biochemical recurrence (BCR) occurs in 20-50% of patients with prostate cancer (PCa) undergoing primary definitive treatment. Patients with high-risk BCR have an increased risk of metastatic progression and subsequent PCa-specific mortality, and thus could benefit from treatment intensification. Given the increasing complexity of diagnostic and therapeutic modalities, multidisciplinary care (MDC) can play a crucial role in the individualized management of this patient population. This review explores the role for MDC when evaluating the clinical evidence for the evolving definition of high-risk BCR and the emerging therapeutic strategies, especially with novel hormone therapies (NHTs), for patients with either high-risk BCR or oligometastatic PCa. Clinical studies have used different characteristics to define high-risk BCR and there is no consensus regarding the definition of high-risk BCR nor for management strategies. Next-generation imaging and multigene panels offer potential enhanced patient identification and precision-based decision-making, respectively. Treatment intensification with NHTs, either alone or combined with radiotherapy or metastasis-directed therapy, has been promising in clinical trials in patients with high-risk BCR or oligometastases. As novel risk-stratification and treatment options as well as evidence-based literature evolve, it is important to involve a multidisciplinary team to identify patients with high-risk features at an earlier stage, and make informed decisions on the treatments that could optimize their care and long-term outcomes. Nevertheless, MDC data are scarce in the BCR or oligometastatic setting. Efforts to integrate MDC into the standard management of this patient population are needed, and will likely improve outcomes across this heterogeneous PCa patient population.

PSMA PET imaging in the diagnosis and management of prostate cancer

Prostate cancer is the second leading cause of cancer-related deaths in men in the United States. Imaging techniques such as CT, MRI, and bone scans have traditionally been used for diagnosis and staging. Molecular imaging modalities targeting the prostate-specific membrane antigen (PSMA) have recently gained attention due to their high affinity and accuracy. PSMA PET has been combined with other modalities such as multiparametric MRI for better diagnostic and prognostic performance. PSMA imaging has been studied at different clinical settings with a wide range of disease aggressiveness. In this review we will explore the role of PSMA PET in high-risk prostate cancer staging, biochemical recurrence, and castration-resistant prostate cancer. The primary focus of this review article is to examine the latest developments in the use of PSMA imaging and emphasize the clinical situations where its effectiveness has been demonstrated to significantly impact the treatment of prostate cancer. In addition, we will touch upon the potential future advancements of PSMA PET imaging and its evolving significance in the management of prostate cancer.

Treatment of primary cancer in metastatic hormone-sensitive prostate cancer

PURPOSE OF REVIEW

Recently, there has been emerging interest in the treatment of primary tumours in metastatic prostate cancer based on major trials that have provided evidence for radiation therapy and cytoreductive radical prostatectomy. Preclinical studies have further established the molecular features of metastatic disease that provide a rationale for primary treatment.

RECENT FINDINGS

Several randomised controlled trials and other prospective studies have demonstrated a benefit in overall survival, predominantly in low-volume disease. Advancements in precision medicine also offer insight into improving selection, staging and monitoring.

SUMMARY

In this review, the authors highlight and review recent data on emerging and established treatment options and shift towards personalised medicine for hormone-sensitive metastatic prostate cancer.

Health-related quality of life of metastatic prostate cancer patients treated with prostate Radiotherapy

BACKGROUND

The impact of prostate radiotherapy on patient-reported health-related quality of life (HRQoL) significantly influences the outcomes of metastatic prostate cancer. We measured and compared HRQoL of metastatic prostate cancer patients who received cytoreductive prostate radiotherapy.

METHODS

Between November 23, 2020, and November 21, 2022, we recruited 70 metastatic prostate cancer patients at the Department of Clinical Oncology at Suez Canal University Hospital. Patients were eligible if they had synchronous and metachronous histopathological confirmed metastatic adenocarcinoma and an Eastern Cooperative Oncology Group performance status ≤ 2. Random allocation was performed for either definitive local radiotherapy concurrent with the standard androgen deprivation therapy (ADT) or to the standard ADT alone. Definitive radiotherapy was delivered conventionally (70 Gy/35 fractions) or through the hypofractionated regimen (55 Gy/20 fractions). Patients completed the comprehensive European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-PR25) at baseline, then at three-month intervals for one year. The primary endpoint was patient-reported HRQoL, with secondary endpoints including toxicity and radiographic progression-free survival (rPFS). Mean HRQoL scores between groups were compared using the independent samples t-test.

RESULTS

We observed clinically significant improvements in urinary and bowel functions between baseline, 3-month, 6-month, and 12-month intervals after receiving definitive prostate radiotherapy. Patients in the radiotherapy group had significantly lower urinary symptoms scores than the control group. However, sexual activity and functioning showed significant deterioration.

CONCLUSION

Cytoreductive prostate radiotherapy in metastatic prostate cancer patients significantly improved urinary functioning, preserved bowel functioning but was associated with worsening of sexual functioning.

TRIAL REGISTRATION

This trial was registered on (27/04/2023) with pactr.samrc.ac.za, PACTR202305854600529, URL: https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=25510 .

Stereotactic Body Radiation Therapy Salvage for Lymph Node Recurrent Prostate Cancer in the Era of PSMA PET Imaging

PURPOSE OF REVIEW

Our understanding of patterns of prostate cancer recurrence after primary treatment of localized disease has significantly evolved since the development of positron emission tomography (PET) agents targeting prostate cancer. Previously, most biochemical recurrences were not associated with imaging correlates when restaging with computed tomography (CT), magnetic resonance imaging (MRI), or bone scintigraphy and, hence, were typically assumed to represent occult metastases. A rising prostate specific antigen (PSA) after previous local therapy prompting a PET scan showing uptake limited to regional lymph nodes is an increasingly common clinical scenario as advanced prostate cancer imaging becomes more widely utilized. The optimal management strategy for patients who have lymph node recurrent prostate cancer is both unclear and evolving, particularly in terms of local and regionally directed therapies. Stereotactic body radiation therapy (SBRT) utilizes ablative radiation doses with steep gradients to achieve local tumor control while sparing nearby normal tissues. SBRT is an attractive therapeutic modality due to its efficacy, favorable toxicity profile, and flexibility to administer elective doses to areas of potential occult involvement. The purpose of this review is to briefly describe how SBRT is being implemented in the era of PSMA PET for the management of solely lymph node recurrent prostate cancer.

RECENT FINDINGS

SBRT has been shown to effectively control individual lymph node tumor deposits within the pelvis and retroperitoneum for prostate cancer and is well-tolerated with a favorable toxicity profile. However, a major limitation thus far has been the lack of prospective trials supporting the use of SBRT for oligometastatic nodal recurrent prostate cancer. As further trials are conducted, its exact role in the treatment paradigm of recurrent prostate cancer will be better established. Although PET-guided SBRT appears feasible and potentially beneficial, there is still considerable uncertainty about the use of elective nodal radiotherapy (ENRT) in patients with nodal recurrent oligometastatic prostate cancer. PSMA PET has undoubtedly advanced imaging of recurrent prostate cancer, revealing anatomic correlates for disease recurrence that previously went undetected. At the same time, SBRT continues to be explored in prostate cancer with feasibility, a favorable risk profile, and satisfactory oncologic outcomes. However, much of the existing literature comes from the pre-PSMA PET era and integration of this novel imaging approach has led to greater focus on new and ongoing clinical trials to rigorously evaluate this approach and compare to other established treatment modalities utilized for oligometastatic, nodal recurrence of prostate cancer.

Contemporary Review of Multimodality Imaging of the Prostate Gland

Tissue changes and the enlargement of the prostate, whether benign or malignant, are among the most common groups of diseases that affect men and can have significant impacts on length and quality of life. The prevalence of benign prostatic hyperplasia (BPH) increases significantly with age and affects nearly all men as they grow older. Other than skin cancers, prostate cancer is the most common cancer among men in the United States. Imaging is an essential component in the diagnosis and management of these conditions. Multiple modalities are available for prostate imaging, including several novel imaging modalities that have changed the landscape of prostate imaging in recent years. This review will cover the data relating to commonly used standard-of-care prostate imaging modalities, advances in newer technologies, and newer standards that impact prostate gland imaging.

Prostate-specific Membrane Antigen Positron Emission Tomography in the Staging of Newly Diagnosed Prostate Cancer: Is More Sensitivity Always Better?

Higher diagnostic accuracy, even if desirable, is not automatically associated with better outcomes. If used in settings validated with less sensitive imaging modalities, it is of paramount importance to prospectively ascertain that the higher sensitivity of prostate-specific antigen membrane-based imaging will benefit patients, and will probably not do harm.

Bone Scintigraphy versus PSMA-Targeted PET/CT or PET/MRI in Prostate Cancer: Lessons Learned from Recent Systematic Reviews and Meta-Analyses

Positron emission tomography (PET) combined with computed tomography (PET/CT) or magnetic resonance imaging (PET/MRI) using several radiopharmaceuticals [...]