Numerous studies have demonstrated that patients with rapidly rising PSA after biochemical recurrence are at high risk of developing metastases and dying from prostate cancer. If remedial radiotherapy is administered, it should be initiated before PSA levels exceed 0.5 ng/ml. Patients with biochemical recurrence occurring long after surgery, slow rise in PSA levels, low tumor grade, and no seminal vesicle invasion or lymph node metastases are most likely to respond well to radiotherapy. Patients with biochemical recurrence should be thoroughly evaluated to determine if clinical recurrence has occurred. As with combined adjuvant radiotherapy, the role of remedial radiotherapy is controversial. Some patients have an equally good prognosis without remedial radiotherapy, while some patients develop distant metastases even with remedial radiotherapy. If it is impossible to determine whether clinical recurrence has occurred, a comprehensive analysis of whether local recurrence or extensive metastasis may have occurred will be made based on the time of PSA rise after surgery, the rate of PSA rise, PSA multiplication time, Gleason score, pathological stage, etc. For patients with a high possibility of local recurrence, watchful waiting treatment or salvage treatment may be used, while for patients with a high possibility of extensive metastasis, endocrine therapy may be used.