Medical Reading

Patterns Of Local Failure Following Prostate Brachytherapy

October 15, 2017

UroToday- An adequate radiation dose and administration of androgen-deprivation therapy (ADT) are the keys to local control in patients with prostate cancer (CaP) undergoing brachytherapy according to a report by Dr. Nelson Stone in the May 2007 issue of the Journal of Urology.

A total of 1,562 patients without lymph node metastasis were treated with brachytherapy for CaP at one institution. Patients were stratified into low, intermediate or high risk. Low risk men with prostate volumes >50cc were treated with 3-5 months of ADT, intermediate risk with 6 months ADT and high risk with 9 months ADT. Radiation consisted of 160Gy 125I for low risk disease, 124Gy 103Pd for intermediate risk, and 100Gy 103Pd for high risk followed by 45Gy external beam radiotherapy. Those with a positive seminal vesicle biopsy also received seed placement in the seminal vesicles.

Of the total number of patients, 508 had a prostate biopsy at 2 years following implantation and make up the reported study cohort. Median age was 66 years and patients were categorized as low, intermediate and high risk in 43%, 24%, and 33%. A total of 237 patients received ADT as described above. In those with a positive prostate biopsy at 2 years, a repeat biopsy was offered yearly until it became negative or there was evidence of PSA progression.

Median follow-up was 6.7 years and a total of 643 biopsies were performed in 508 men. In these 508 men, a positive biopsy was documented in 39 (7.7%) and 99 (19.5%) had PSA failure. Multivariable analysis demonstrated that radiation dose and use of ADT were significantly associated with a positive biopsy. Only radiation dose was significant in low risk men, while dose and ADT were significant in intermediate risk men and ADT and combination radiation therapy significant in high risk men. Among intermediate risk men, high dose radiation plus ADT decreased the risk of a positive biopsy from 10.8% to 2%. In men with high risk disease, high dose radiation plus ADT decreased the positive biopsy rate from 28.6% to 6.5%.

The 10-year freedom from biochemical failure was 84% for the entire cohort. If the final biopsy was negative, there was an 80% freedom from PSA failure at 10 years compared to 27.3% for a positive biopsy. There were 52 men with a positive biopsy at year 2 and 23 of these had a subsequent negative biopsy.

Stone NN, Stock RG, White I, Unger P

J Urol 2007; 177(5):1759-64
Reviewed by UroToday Contributing Editor Christopher P. Evans, MD

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