Patterns of Failure Following the Brachytherapy Management of Prostate Cancer
There are relatively few studies with long-term outcomes for men who have been treated with radioactive seed implant (brachytherapy) for prostate cancer. It is important to understand treatment failures after brachytherapy in order to decide which patients should be offered this treatment modality. This evaluation included 2,456 patients with T1-T3 disease, treated with brachytherapy at Mt. Sinai Medical Center with median follow up of 82 months.
One hundred and eighty-four patients developed a PSA failure, and of these 64% were considered to be “high risk” prior to treatment. PSA doubling time is the time it takes for the PSA value to double, and this is used as a measure for evaluating disease recurrence. Longer doubling times are related to local recurrence, whereas shorter doubling times generally indicate distant metastases. Gleason score was significantly related to freedom-from-developing distant metastases (89% without recurrence for Gleason <=6, 75% for Gleason 7, and 50% for Gleason 8-10). High- risk patients make up the majority of treatment failures.
Local failure occurred in one-third of patients, and was associated with lower radiation doses and longer doubling times. Distant metastasis occurred in one-fourth of patients, and was associated with shorter doubling times, early PSA failure, and higher Gleason scores. This data suggests that seed implant (brachytherapy) should probably be reserved for low risk patients and highly selected intermediate risk patients. The risk of relapse appears too high to justify seed implant in high-risk patients.
It would be nice to have an analysis of the toxicities related to these implants. It may be the case that external beam radiation can produce similar and/or superior outcomes with less acute and long-term toxicities than brachytherapy. However, it will be hard to compare them head-to-head, because the quality of an implant is very operator-dependent. Centers with a high volume of cases and experience with brachytherapy tend to have superior outcomes when compared to centers that perform them sporadically.