Radiotherapy of oligometastatic prostate cancer: a systematic review

Abstract

Background Due to improved imaging sensitivity, the term “oligometastatic” prostate cancer disease is diagnosed more often, leading to an increasing interest in metastasis-directed therapy (MDT). There are two types of radiation based MDT applied when treating oligometastatic disease: (1) stereotactic body radiation therapy (SBRT) generally used for bone metastases; or (2) SBRT for isolated nodal oligometastases combined with prophylactic elective nodal radiotherapy. This review aims to summarize current evidence data, which may shed light on the optimal management of this heterogeneous group of patients. Methods A systematic review of the Medline database through PubMed was performed according to PRISMA guidelines. All relevant studies published up to November 2020 were identified and screened. Fifty-six titles were included. Besides outcome parameters, different prognostic and predictive factors were assessed, including site of metastases, time between primary treatment and MDT, use of systemic therapies, hormone sensitivity, as well as pattern of recurrence. Findings Evidence consists largely of retrospective case series and no consistent precise definition of oligometastasis exists, however, most investigators seem to acknowledge the need to distinguish between patients presenting with what is frequently called “synchronous” versus “metachronous” oligometastatic disease. Available data on radiotherapy as MDT demonstrate high local control rates and a small but relevant proportion of patients without progressive disease after 2 years. This holds true for both hormone sensitive and castration resistant prostate cancer diseases. The use of 68Ga-PSMA PET/CT for staging increased dramatically. Radiation doses and field sizes varied considerably among the studies. The search for relevant prognostic and predictive factors is ongoing. Conclusions To our best knowledge this review on oligometastatic prostate cancer included the largest number of original articles. It demonstrates the therapeutic potential and challenges of MDT for oligometastatic prostate cancer. Prospective studies are under way and will provide further high-level evidence.

Treatment Strategies for High-Risk Localized and Locally Advanced and Oligometastatic Prostate Cancer

“…In addition to conventional imaging methods using CT and bone scintigraphy, many reports have used positron emission tomography-CT (PET-CT) using 18 F-fluorodeoxyglucose and 11 C-choline, as well as whole-body MRI (WB-MRI) for diagnosis. Shen et al conducted a meta-analysis of the diagnostic performance of bone metastases and reported that choline PET-CT, MRI, and bone scintigraphy had sensitivities of 87%, 95%, and 79%, respectively, and specificities of 97%, 96%, and 82%, respectively [86].…”

“…The goals may be to control the cancer, slow down further metastasis, and avoid or delay systemic therapyrelated toxicity. A systematic review has given an overview of the current evidence for MDT in oligometastatic PC [11]. Local control rates at two years ranged between 76-100%.…”

“…In recent years, however, the significance of combined local treatment has been discussed, and the results of large-scale clinical trials have been reported with and without combined RT [6,10]. In addition, attempts to further enhance disease control by concomitant metastasis-directed therapy (MDT) have been made [11][12][13], and radical curing of oligometastatic PC may be expected in the future. The present article reviews the definition, diagnosis, and treatment (especially RT) of locally advanced (focusing on very high-risk PC) and oligometastatic PC, focusing on previous reports.…”

Recent Advances in the Management of Hormone-Sensitive Oligometastatic Prostate Cancer

“…16 The interest towards PSMA-targeted imaging has increased during the last years, as, thus far, it was proven to have the highest metastases detection rates over the other available imaging methods. 8 In particular, studies showed 68 Ga-PSMA PET/CT consistently outperforming choline PET/CT at low PSA values, 20 with reported detection rates of 15-58%, 25-73%, 69-100% for PSA ranges of 0.2-0.5 ng/mL, 0.5-1 ng/mL and 1-2 ng/mL, respectively. 8 Moreover, a high level of interobserver agreement was demonstrated for 68 Ga-PSMA PET/ CT, both for nodal and bony lesions.…”

“…8 In particular, studies showed 68 Ga-PSMA PET/CT consistently outperforming choline PET/CT at low PSA values, 20 with reported detection rates of 15-58%, 25-73%, 69-100% for PSA ranges of 0.2-0.5 ng/mL, 0.5-1 ng/mL and 1-2 ng/mL, respectively. 8 Moreover, a high level of interobserver agreement was demonstrated for 68 Ga-PSMA PET/ CT, both for nodal and bony lesions. 21,22 Admittedly, PSMA-based techniques may fail to detect clinical progression when PSMA is either absent or scarcely expressed.…”