Immunotherapy is currently revolutionizing the field in oncology. However, prostate cancer is poorly responsive to immune checkpoint inhibition. The combination of immunotherapy and radiotherapy is an emerging clinical treatment aradigm. X-ray radiation treatment can activate both the adaptive and innate immune systems through directly killing tumor cells, causing mutations in tumor-derived peptides, and causing localized inflammation that increases immune cell trafficking to tumors. Recently, preclinical study reported that immune checkpoint inhibition combined with radiotherapy treats CPRC with significant increases in median survival compared to drug alone.

Permanent brachytherapy is one of those standard treatments for localized prostate cancer patients.

Biopsy confirms prostate cancer. Blood and urine of localized prostate cancer patients will be collected before and at different time points after permanent brachytherapy (1, 3, 6, and 12 months)

Inclusion Criteria:

- Biopsy confirms prostate cancer

Localized Prostate Cancer, ≤cT3

No chemotherapy or Hormonal therapy before Permanent Brachytherapy

Exclusion Criteria:

- Unacceptable operative risk

Poor anatomy which in the opinion of the radiation oncologist could lead to a suboptimal implant (e.g.,large or poorly healed transurethral resection of the prostate (TURP) defect, large median lobe, large gland size).

Pathologically positive lymph nodes

Significant obstructive uropathy

Distant metastases

Use steroids regularly

The diagnosis was accompanied by immune-related diseases

Allergic constitution

Abnormal white blood cell and lymphocyte counts

Ever underwent other treatments for prostate cancer, such as chemotherapy or Hormonal therapy

Accompanied by other malignancies

Splenectomy

HIV positive

Receive an anti-infective vaccine for the last 6 months

localized prostate cancer patients