Radioactive seed implants work as a form of radiation therapy for prostate cancer, according to WebMD. This procedure is also commonly known as brachytherapy or internal radiation therapy.
There are two types of prostate brachytherapy: permanent and temporary. With permanent therapy, anywhere from 40 to 100 radioactive seeds are implanted into the prostate gland using ultrasound for guidance, a technique that allows a high dose of radiation to be delivered to the prostate with limited harm to surrounding tissue. With temporary therapy, needles filled with radioactive material are placed in the prostate gland for five to 15 minutes, a procedure that is repeated two to three times over the course of several days, according to WebMD.
For many types of cancers, brachytherapy takes one to two days, as compared to five to seven weeks for external beam radiation therapy or EBRT. Brachytherapy is also combined with other treatments, depending on the stage and type of cancer, notes Cancer Treatment Centers of America.
Research shows successful outcomes with brachytherapy, external beam radiation therapy and open radical prostatectomy, although higher-dose radiation using EBRT with brachytherapy appears to have better relapse-free survival outcomes for high-risk and high-grade cancers, according to the Prostate Cancer Center of Seattle.