Three-dimensional computed tomography-guided monotherapeutic pararectal brachytherapy of prostate cancer with seminal vesicle invasion.
OBJECTIVE
To treat patients with prostate cancer and seminal vesicle invasion with monotherapeutic three dimensional computed tomography (3-DCT)-guided posterior pararectal brachytherapy.


METHODS
Three hundred and sixty two patients with clinical stage T1 a,b or T2 a,b of prostate cancer were referred for 3-DCT-guided brachytherapy. Each underwent ftirther staging with 3-D CT-guided pararectal biopsy of the seminal vesicles under local anesthesia during the pre-treatment CT-planning. Forty-three patients (12%) were upstaged to T3 cNoMo disease. In the set of 43 patients, Eight had Gleason's score< or =6, 24 Gleason's score=7, and 11 patients > or =8. Initial PSA was <10 ng/ml in 14 patients, 10-20 ng/ml in 11 patients, and >20 in 18 patients. Of the 43 patients, 37 patients were treated monotherapeutically with 3-D CT-guided brachytherapy. No patients received hormone therapy after the implant. The prescribed dosage to the seminal vesicles and prostate is 120 Gy with Pd-103 seeds and 144 Gy with 1-125 seeds.


RESULTS
The prescribed dosage was achieved in all 37 patient's throughout the seminal vesicles whose range of target radiation extended 5-10 mm outside the target in the adjacent fat as calculated with post-implant CT-dosimetry with Varian Brachy Vision or MMS software. Prostate Specific Antigen (PSA) outcome data were available in 34 patients treated with monotherapy and follow up ranged from 12-56 months (median, 24 months). Decreased PSA levels were stratified into six groups based on the presenting Gleason's score and initial PSA. In the first group (with Gleason's score< or =6 and initial PSA <20 ng/ml), PSA levels decreased to less than 0.5 ng/ml in all seven patients (100%) after brachytherapy. In the second group (with Gleason's=7 and initial PSA<20 ng/ml), PSA levels decreased to less than 1 ng/ml in 11 of 13 patients (85%); additionally PSA levels decreased to less than 0.5 ng/ml in ten patients (77% in this group). In the third group (with Gleason's score=7 and initial PSA> 20 ng/ml), PSA decreased to less than 0.5 ng/ml in four out of eight patients (50%). All of the patients in the fourth group (with Gleason's score> or =8 and initial PSA<20 ng/ml) decreased their PSA levels to less than 0.5 ng/ml in three of three patients. PSA decreased less than 0.5 ng/ml in two out of three patients (67% in the last group with Gleason's score> or =8 and initial PSA> 20 ng/ml). There were no patients with Gleason's score of 1-6 and greater than 20 ng/ml initial PSA. Patients, irrespective of the Gleason's score and PSA, had an overall response of decreased PSA (less than 1 ng/ml) of 79%.


CONCLUSIONS
3-D CT-guided brachytherapy delivers adequate dosage to the seminal vesicles. Clinical and biochemical results are encouraging in patients with low initial PSA levels regardless of their Gleason's scores, but longer-term data in a greater number of patients is necessary.
Koutrouvelis
P
P
Uro-Radiology Prostate Institute, 8320 Old Courthouse Road #150, Vienna, Virginia 22182, USA.
Lailas
N
N
Hendricks
F
F
Gil-Montero
G
G
Sehn
J
J
Katz
S
S
D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D005500:Follow-Up Studies; D005834:Genital Neoplasms, Male / Q000000981:diagnostic imaging / Q000532:radiotherapy / Q000556:secondary*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011829:Radiation Dosage; D011881:Radiotherapy, Computer-Assisted; D012669:Seminal Vesicles / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed