Stereotactic Body Radiotherapy (SBRT) for Oligometastatic Prostate Cancer

The aim of this study is to test the safety and feasibility of SBRT without ADT in oligometastatic prostate cancer in patients for whom the standard treatment is ADT, and to further explore how long only radiotherapy for oligometastases can prolong biochemical progression-free survival (bPFS). In this study, men with oligometastatic prostate cancer lesions will be randomized (1:1) to ADT versus SBRT. Within 6 weeks of the oligometastases diagnosis, ADT or SBRT (30-50Gy with 3-5 fractions) will be administered.

The oligometastatic disease state is an increasingly recognized phenomenon in prostate cancer. Ga-68 PSMA PET/CT has high accuracy in the diagnosis metastases from prostate cancer. In this protocol, pretreatment Ga-68 PSMA PET/ CT shall be performed in all patients.

ADT is considered standard of care treatment for advanced prostate cancer. But hormonal therapy can have side effects that greatly trouble men and lead to castration-resistant prostate cancer (CRPC). Any effort to delay the start of hormonal therapy would be an advantage to the patient. Stereotactic body radiation therapy (SBRT) is highly focused radiation, given in a very dose intensive fashion and delivered in usually less than one week. SBRT has been shown to be very effective on bone or lymph nodes metastases. Therefore, we are studying the safety and feasibility of SBRT on patients with five or fewer prostate cancer bone or lymph nodes metastases to determine if we can stall the use of hormonal therapy and/or prevent other site metastases from developing elsewhere in the body.

Eligibility Criteria:
Inclusion Criteria:

* 80 years old

  * Histologically confirmed adenocarcinoma of the prostate
  * Prostate cancer treated with curative intent (radical prostatectomy, primary radiotherapy, or a combination of both)
  * Ga-68 prostate-specific membrane antigen (PSMA) PET/CT evidence of one to three metastases (bone or lymph node) within 6 weeks of enrolment, if the position of oligometastases is judged by the doctor to be in the same radiotherapy area, the number of metastases can be appropriately increased to 5
  * Without ADT treatment
  * PSA\< 50ng/ml
  * ECOG performance status 0-2
  * Written informed consent according to ICH/GCP regulations before registration and prior to any trial specific procedures

Exclusion Criteria:

* Any previous or ongoing treatment of oligometastases including radiotherapy, ADT, chemotherapy, focal treatment, etc.
* Unstable lesions with spinal or long bone metastases
* A tumor located at less than 3 mm from the urethra or rectum when measured at the MRI

  * 4 metastases, or if the metastases are in the same radiotherapy area, ≥6 metastases
* Histologically confirmed neuroendocrine tumor or small cell carcinoma of the prostate
* Severe or active co-morbidity likely to impact on the advisability of SBRT like severe liver or kidney dysfunction, etc.
* Patients with other malignancies, or acute or other severe infections, with ulcerative colitis, inflammatory bowel disease, etc.
* Patients who have participated in other clinical trials for less than three months
* Unsuitable to participate in this clinical trial judged by the investigator