Oligometastases in prostate cancer: restaging stage IV cancers and new radiotherapy options

Abstract

There are various subgroups of patients with metastatic prostate cancer: polymetastatic, oligometastatic, or oligo-recurrent cancers whose progression follows different courses and for whom there are different treatment options. Knowledge of tumor dissemination pathways and different genetic and epigenetic tumor profiles, as well as their evolution during disease progression, along with new diagnostic and therapeutic advances has allowed us to address these situations with local ablative treatments such as stereotactic body radiation therapy or stereotactic radiosurgery. These treatments provide high rates of local control with low toxicity in metastatic spread for primary cancers including those of pulmonary, digestive, and renal origin, while these types of treatments are still emerging for cancers of prostatic origin. There are several retrospective studies showing the effectiveness of such treatments in prostate cancer metastases, which has led to the emergence of prospective studies on the issue and even some phase II studies intended to prevent or delay systemic treatments such as chemotherapy. Here we collect together and review these past experiences and the studies currently underway. These types of radiotherapy treatments redefine how we approach extracranial metastatic disease and open up new possibilities for combination therapy with new systemic treatment agents.

Benefits of Using Stereotactic Body Radiotherapy in Patients With Metachronous Oligometastases of Hormone-Sensitive Prostate Cancer Detected by [18F]fluoromethylcholine PET/CT

“…Patients referred from other hospitals who underwent SBRT at VUmc, but had the imaging at their own centers were also screened for eligibility. Patients with hormone sensitive oligometastatic disease, defined as ≤4 [ 18 F]FCH PET/CT positive metastatic lesions, were identified for further analysis (9). Patients were included in the analysis if they had a histologically proven diagnosis of prostate cancer, were initially treated with curative intent, had biochemical PSA relapse, had metabolically active oligometastatic disease on [ 18 F]FCH PET/CT and received SBRT to all lesions as initial oligometastatic treatment.…”

“…For the subgroup of patients with oligometastatic disease, typically defined as less than fouror five metastases in bone and/or lymph nodes (8,9), local therapy might represent an attractive treatment paradigm. Stereotactic body radiation therapy (SBRT), defined as high-dose external beam radiotherapy typically delivered in only a few fractions using advanced techniques that allow for relative sparing of nearby normal tissues, is a non-invasive ambulatory local therapy (10).…”

“…Our results are broadly in line with other recently published studies (using both [ 18 F]FCH PET/CT and [ 18 F]FDG PET/CT to identify oligometastatic disease), despite some differences in study design and patient population. Although oligometastatic disease has generally been defined as ≤5 lesions(9,28), the majority of patients who receive local therapy, have only 1 or 2 lesions (95% in this study) and patients with fewer lesions may have a better prognosis(9). We therefore selected a more conservative definition of oligometastatic disease for this analysis, of ≤4 lesions.Pasqualetti et al treated 23 patients (≤3 lesions detected by [ 18 F]FCH PET/CT), with repeated SBRT until patients developed> 3 lesions.…”

PSMA-Based Detection of Prostate Cancer Bone Lesions With 18F-DCFPyL PET/CT: A Sensitive Alternative to 99mTc-MDP Bone Scan and Na18F PET/CT?

“…The sensitive detection of metastatic sites is of critical importance, as there is growing evidence that patients with a limited number of disease foci may benefit from directed treatment such as stereotactic ablative radiation. 2–4 …”

CyberKnife stereotactic radiosurgery and stereotactic ablative radiation therapy of patients with prostate cancer bone metastases.

“…According to current knowledge, the criteria for performing ablative treatment of patients with metastases are: oligorecurrence, good performance status, five or less metastases located preferably in bone (although the current guidelines do not include the possibility of ablative treatment for metastatic prostate cancer as standard treatment) [10]. In the majority of stereotactic radiosurgery (SRS)/ stereotactic ablative radiotherapy (SABR) studied schemes used for treating prostate cancer oligometastases average total dose varies from 8 to 50 Gy [10 -18].…”