Dosimetry doesn't seem to predict the control of organ-confined prostate cancer after I-125 brachytherapy. Evaluation in 150 patients.
OBJECTIVE
To evaluate the dose-response relationship (D90 >144 Gy: probable absence of biochemical failure) in patients with prostate cancer treated by iodine-125 (I-125) brachytherapy.


METHODS
From May 1999 to December 2006, 150 patients were treated by I-125 brachytherapy. The median follow-up was 60 months. All patients had clinical stage T1-T2, PSA < or =10 ng/ml, Gleason Scores < or = 3+3=6, IPSS >14 ml/sec. and prostate weight <50 gr. Implantation was ultrasound-guided, using a real-time technique and loose seeds of I-125 (dose 160 Gy). After 30 days, a post-implantation assessment was performed by pelvic CT scan for a definitive evaluation of the D90. All patients were subjected to clinical evaluation, PSA dosage and compilation of IPSS and IEFF questionnaires. In the event of biochemical failure (ASTRO), a prostate biopsy was performed. A D90 >144 Gy was considered the cut-off in order to predict the absence of biochemical failure.


RESULTS
Biochemical failure was observed in 9 patients: 5 with positive and 4 with negative prostate biopsies. The D90 >144 Gy cut-off was not achieved in 18 patients at the post-implantation assessment, however only 2 of them (one of whom had a positive biopsy) had biochemical failure (11.1%). On the other hand, only 2 of the 9 patients with biochemical failure had a D90 < 144 Gy while 6 patients had D90 >150 Gy, 5 with positive prostate biopsies.


CONCLUSIONS
In our experience, the D90 >144 Gy cut-off does not seem to predict, in a reliable way, the control of prostate cancer following brachytherapy. Limitations of the analysis were the number of the patients, the learning curve, dosimetry processing and the relatively short follow-up.
Gastaldi
Emilio
E
Department of Surgery, Division of Urology, San Paolo Hospital, Savona, Italy. emilio.gastaldi@tiscali.it
Chiono
Luciano
L
Gallo
Fabrizio
F
Schenone
Maurizio
M
Ninotta
Gaetano
G
Chiarlone
Renato
R
Ghiso
Giovanni
G
Giberti
Claudio
C
D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D001706:Biopsy; D001918:Brachytherapy / Q000009:adverse effects; D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D018579:Patient Selection; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011859:Radiography; D011874:Radiometry; D012189:Retrospective Studies; D018570:Risk Assessment; D011795:Surveys and Questionnaires; D017211:Treatment Failure; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D007457:Iodine Radioisotopes; D017430:Prostate-Specific Antigen