In patients with metastatic prostate cancer (PCa) who receive androgen deprivation therapy (ADT), the sensitivity to castration will eventually disappear due to the selection of castration-refractory clones. This will lead to the stage of metastatic castration-refractory prostate can-cer (mCRPC), which is incurable and results in a median overall survival of 2-3 years.
Treatment options for patients with mCRPC include several systemic agents, such as andro-gen receptor-targeted agents (ARTA), chemotherapy (docetaxel, cabazitaxel) and bone-targeting agents (radium- 223). Clinical progression and, to a lesser extent, biochemical pro-gression traditionally imply a switch to the next line systemic treatment (NEST). Within patients with mCRPC, there is a subgroup showing oligo-progression, defined as the progression of up to 3 lesions, including both metastatic and/or local relapse. Oligoprogression reflects a heterogeneous treatment response, which, in turn, reflects the heterogeneity of the clonogenic cells that give rise to mCRPC. Retrospective studies suggest that metastasis-directed radiotherapy (MDRT) to these oligoprogressive lesions delayed the need for NEST. Recently, promising results were published on the use of MDRT in the oligopro-gressive mCRPC (omCRPC) setting, with a NEST-free survival (NEST-FS) of 21 months in well selected patients. Currently, in The Netherlands, patients with omCRPC are frequently referred and treated with MDRT, but a clear treatment protocol and inclusion/selection criteria are missing. Moreover, the exact benefit of MDRT in patients with omCRPC remains unclear, as prospective evi-dence for MDRT in omCRPC is lacking.
Adenocarcinoma of the prostate.
mCRPC setting, with testosterone level < 50 ng/dl or 1.7 nmol/l.
Oligoprogressive disease diagnosed on PSMAscan; defined as the progression of pre-existing metastatic disease, and/or the appearance of new metastases and/or the appearance of a local relapse with a maximum of 3 lesions in total.
Patients currently treated with ADT, whether combined with another systemic treatment such as ARTA, chemotherapy.
Serum testosterone level > 50 ng/ml or > 1.7 nmol/l.
Presence of more than 3 progressive/new metastatic lesions and/or local recurrence (which counts for 1 lesion).
Active malignancy other than prostate cancer that can potentially interfere with the interpretation of the trial, except non-melanoma skin cancer or non-invasive urothelial cell carcinoma.
Local recurrence in the prostate after previous radiotherapy