Post-nerve-sparing prostatectomy, dose-escalated intensity-modulated radiotherapy: effect on erectile function.
OBJECTIVE
The advent of widespread prostate-specific antigen screening has resulted in more younger, potent men being diagnosed with early-stage, organ-confined prostate cancer amenable to definitive surgery. Nerve-sparing prostatectomy is a relatively new surgical advance in the treatment of prostate cancer. Very few data exist on the effect of postoperative radiotherapy (RT) on erectile function after nerve-sparing prostatectomy. They are based on conventional techniques using moderate doses of radiation, 45-54 Gy. Intensity-modulated RT (IMRT) is becoming more widespread because it allows dose escalation with increased sparing of the surrounding normal tissue. We investigated the effect of postprostatectomy, high-dose IMRT on patients' erectile function.


METHODS
A review of patient records found 51 patients treated between April 1998 and December 2000 with IMRT after unilateral or bilateral nerve-sparing prostatectomy. The pathologic disease stage in these patients was T2 in 47.4% and T3 in 52.6%. Postoperatively, 4 patients received hormonal ablation consisting of one injection of Lupron Depot (30 mg) 2 months before RT. The median age was 65 years (range 46-77) at the time of RT. The prescribed dose was 64 Gy (range 60-66). The mean dose was 69.6 Gy (range 64.0-72.3). Erectile function was assessed before and after RT by questionnaires. Sexual potency was defined as erectile rigidity adequate for vaginal penetration.


RESULTS
Of the 51 patients, 18 (35.3%) maintained their potency and 33 (64.7%) became impotent after nerve-sparing prostatectomy. Patients who underwent bilateral nerve-sparing prostatectomy had higher rates of postoperative potency than did those who underwent unilateral nerve-sparing surgery (72.2% vs. 27.8%; p = 0.025). The follow-up for the entire group was 19.5 months. All 18 patients (100%) who were potent postoperatively remained potent after RT. The median follow-up for the 18 potent patients was 27.2 months, significantly longer than that of the impotent group, 13.0 months (p <0.001).


CONCLUSIONS
This is the first report on the effects of dose-escalated IMRT on men who have undergone nerve-sparing prostatectomy. Despite the high dose (mean dose 69.6 Gy) to the prostate bed and nerves, postoperative IMRT had no negative effect on erectile function for the patients who remained potent after nerve-sparing prostatectomy. Longer term follow-up and a larger cohort of patients are warranted to confirm these findings.
Department of Radiology, Section of Radiation Oncology, Baylor College of Medicine and Methodist Hospital, 6565 Fannin, Houston, TX 77030, USA.
Michael D
MD
Bastasch
Bin S
BS
Teh
Wei-Yuan
WY
Mai
L Steven
LS
Carpenter
Hsin H
HH
Lu
J Kam
JK
Chiu
Shiao Y
SY
Woo
Walter H
WH
Grant
Brian J
BJ
Miles
Dov
D
Kadmon
E Brian
EB
Butler
D000368:Aged; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010410:Penile Erection / Q000528:radiation effects; D011468:Prostatectomy / Q000009:adverse effects / Q000379:methods*; D011471:Prostatic Neoplasms / Q000503:physiopathology / Q000532:radiotherapy* / Q000601:surgery; D011879:Radiotherapy Dosage