[Low-dose radiotherapy of localized prostate neoplasms: How low is high enough?].
BACKGROUND
According to the American Patterns of Care Studies, at least 70 Gy are required to achieve local control of large or undifferentiated carcinomas of the prostate. More recent data on repeated measurements of the prostate-specific antigen (PSA) cast doubt on the radiocurability of tumors with markedly elevated PSA.


METHODS
With a retrospective analysis, the treatment results of local radiotherapy to mid-sized pelvic volumes with a median dose of 66 Gy (1979 to 1988, n = 118) are compared to the outcome after radiotherapy to small prostatic volumes with a median dose of 70.2 Gy (1989 to 1992, n = 126).


RESULTS
Overall survival at 5 years was 65.9% and 82.3%, respectively. Patients treated at a later time had the same life expectancy as expected for the normal population. Distant disease-free survival was identical in both groups (70.4 and 74.3% at five years). Local control could not be assessed by digital rectal examination in a large part of the patients. However, in 50 patients without any pretreatment, the course of PSA was followed. Pretreatment values of > 30 ng/ml were highly predictive for "biochemical relapse" (rising values) within 2 years. Despite individual shielding of the rectum, the rate of symptomatic proctitis rose from 1.7% to 5.6% in patients treated 1989 to 1992.


CONCLUSIONS
We found no negative impact of decreasing the target volume on the overall and distant disease-free survival. The rate of symptomatic proctitis has increased with higher target doses despite better shielding of the rectum, but has remained within an acceptable range. Considering the high rate of biochemical relapse and therefore the poor prognosis associated with initial PSA values > 30 ng/ml, the application of a potentially toxic dose of > 70 Gy in these patients seems hardly justified.
Klinik und Poliklinik für Radioonkoligie, Universitätsspital Zürich.
P
P
Huguenin
C
C
Glanzmann
U M
UM
Lütolf
D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D008875:Middle Aged; D011349:Proctitis / Q000209:etiology; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000276:immunology / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
D017430:Prostate-Specific Antigen
Kleinvolumige Bestrahlung lokalisierter Prostata-karzinome: Wie klein ist gross genug?