Not every prostate cancer patients are suitable for this treatment. The ideal case is tumor confined within one lobe of the gland, low cancer grading, low PSA level and the size of the gland that is not too small (such as the case after transurethral resection of the gland due to bladder tube obstruction), or too large the gland size. However, in the patients who are not ideal, the treatment would be considered, depending on many factors and judgments of the physicians. Those whose prostate glands are large could be treated by hormone first so that the gland size is decreased.
In the patients who have more advanced disease, the treatment needed is to cover the large area such as draining pelvis lymph nodes as well as the primary tumor in the prostate gland. However, the primary cancer which is larger in size, with more cancer cell burden will require higher dose of radiation to eradicate the disease. The Interstitial Brachytherapy can be used as supplement or boost to the prostate gland while sparing surrounding normal tissue of rectum and bladder. The boost dose by this technique is likewise higher than by standard external radiation and thus higher chance of tumor eradication.
Another indication for Interstitial Brachytherapy is the salvage treatment in case the cancer has locally recurred after radical prostatectomy but has not yet has spread outside the primary prostate bed area. The other salvage treatment is for local recurrence after external radiation therapy when the rectum and bladder could not be exposed more to radiation.