I. Diagnosis of prostate cancer (1) Symptoms of prostate cancer Early prostate cancer is usually asymptomatic, but when the tumor invades or blocks the urethra or bladder neck, symptoms similar to lower urinary tract obstruction or irritation will occur, and in severe cases, acute urinary retention, hematuria and urinary incontinence may occur. Bone metastasis will cause bone pain, pathological fracture, anemia, spinal cord compression leading to lower limb paralysis, etc. (2) Diagnosis of prostate cancer Clinically, most patients with prostate cancer can be diagnosed histopathologically by systematic puncture biopsy of the prostate. However, the initial suspicion of prostate cancer is usually determined by rectal examination of the prostate or serum prostate-specific antigen examination before prostate biopsy is performed. Rectal examination combined with PSA is currently recognized as the best primary screening method for early detection of prostate cancer. Other imaging examinations for prostate cancer (1) Computed tomography (CT) examination: CT is less sensitive than MRI for early prostate cancer diagnosis, and the purpose of CT examination for prostate cancer patients is to assist clinicians in clinical staging of the tumor. For the invasion of tumor adjacent tissues and organs and metastatic lymph node enlargement in the pelvis, the diagnostic sensitivity of CT is similar to that of MRI. (2) MRI scan: MRI examination can show the integrity of the prostate envelope, whether it invades the surrounding tissues and organs of the prostate, and MRI can also show the invasion of the pelvic lymph nodes and the foci of bone metastases. It has a more important role in clinical staging. MRI spectroscopy presents different spectral lines according to the differences in the metabolism of citrate, choline and creatinine in prostate cancer tissues and in prostate hyperplasia and normal tissues, which has some value in the diagnosis of prostate cancer. MRI examination is often unable to make a definitive diagnosis when differentiating prostate cancer from lesions such as prostatitis with calcification, larger benign prostatic hyperplasia, prostate scarring, and tuberculosis. Therefore, imaging examination has limitations in the diagnosis of prostate cancer, and the final diagnosis needs to be made by prostate puncture biopsy. The concept of recurrence after radiation therapy for prostate cancer includes biochemical recurrence, clinical local recurrence and distant metastasis. Biochemical recurrence is the precursor of clinical local recurrence and distant metastasis of tumor progression. (1) Definition of biochemical recurrence after radiotherapy: Biochemical recurrence refers to three consecutive PSA elevations after the PSA value drops to the lowest point after radiotherapy, and the exact time of recurrence is the midpoint between the lowest PSA value and the time of the first elevation. (2) The concept of clinical recurrence after radiotherapy: clinical recurrence after radiotherapy includes local recurrence and distant metastasis. Local recurrence refers to the recurrence of prostate cancer after radiotherapy confirmed by prostate puncture after lymph node or distant metastasis is excluded by CT, MRI, bone scan and other imaging examinations. Distant metastasis refers to the evidence of distant dissemination found by imaging examination. 2. Treatment of post-treatment recurrence: Patients with biochemical recurrence are selected for different patients through proper diagnostic evaluation and then watchful waiting treatment or other appropriate treatment methods. Patients with local recurrence can choose salvage therapy, endocrine therapy, etc. For patients with distant metastases, only endocrine therapy is available. (1) Watchful waiting treatment: It is suitable for patients with low-risk prostate cancer, who have early biochemical recurrence after radical radiotherapy, and whose PSA is rising slowly, can consider watchful waiting treatment. (2) Endocrine therapy ①Indications: biochemical recurrence after radiotherapy; clinical local recurrence after radiotherapy, but the patient is not suitable or unwilling to receive salvage therapy; distant metastasis after radiotherapy. ②Timing of endocrine therapy: for early or delayed endocrine therapy after biochemical recurrence. Relevant evidence suggests that early endocrine therapy is more effective than delayed endocrine therapy. (③) Endocrine treatment modalities: depot treatment; anti-androgen drug therapy; maximal androgen blockade therapy; intermittent endocrine therapy, etc. IV. Bone metastasis treatment for hormone-non-dependent prostate cancer For hormone-non-dependent prostate cancer with bone metastasis, the treatment aims are mainly to relieve bone pain, prevent and reduce the occurrence of bone-related events, improve quality of life and increase survival rate. 1.Biphosphonates: Zoledronic acid is the third generation of bisphosphonates, which has the effect of relieving bone pain continuously, reducing the incidence of bone-related events and delaying the time of bone complications. It is currently the first choice for the treatment and prevention of bone metastases from hormone-independent prostate cancer. 2.Radiation therapy: External radiation therapy can improve local and diffuse bone pain. Because of the high chance of multiple bone metastases in prostate cancer patients, the greater the scope and dose of external radiation therapy, the greater the side effects. Radionuclides are effective for multifocal bone pain due to bone metastases from prostate cancer. 89 strontium and 153 samarium are commonly used radionuclides, with 89 strontium emitting higher energy beta rays than 153 samarium, but with a shorter half-life. Phase III clinical studies have shown that strontium 89 or samarium 153 alone can significantly reduce new bone metastases, decrease bone pain symptoms, and reduce the amount of pain medication used. The most common side effect is bone marrow suppression. 3. Analgesic drug therapy: The World Health Organization has established guidelines for pain management, which also apply to patients with prostate cancer bone metastases. Analgesic treatment must be in accordance with this guideline, regular medication (for pain prevention), stepwise medication: from non-opioids to weak opioids and then to strong opioids, and also appropriate adjuvant therapy (including neuroleptics, radiotherapy, chemotherapy, surgery, etc.).