Prospective study of HDR (192Ir) versus MDR (137Cs) intracavitary brachytherapy for carcinoma of the uterine cervix.
OBJECTIVE
The aim of this study was to compare the results of high-dose rate (HDR) and medium-dose rate (MDR) intracavitary brachytherapy for carcinoma of the uterine cervix on the basis of a prospective study and to determine the dose rate conversion factor (DRCF) from low-dose rate (LDR) to MDR via HDR, because a DRCF of 0.54 from LDR to HDR has been widely accepted.


METHODS
Between August 1991 and July 1999, 104 patients were entered into this trial to compare results between HDR (n=54) and MDR (n=50). Three patients were excluded from this study, leaving 54 HDR patients and 47 MDR patients eligible. Method and dose of external beam radiotherapy were the same for both groups. For HDR intracavitary brachytherapy, point A dose was adjusted to 32 Gy/4 fractions for stages I and II, to 30 Gy/4 fractions for stage III, and to 22.5 Gy/3 fractions for stage IV. The corresponding values for MDR were 35.6 Gy/4 fractions, 34 Gy/4 fractions, and 25.5 Gy/3 fractions. The average dose rate at point A was 30 Gy/hour (9.0-65.2) for HDR and 1.7 Gy/hour (1.3-2.2) for MDR. We assumed a DRCF of 0.9 from MDR to HDR.


RESULTS
The 3-year cause-specific survival rates for HDR were 85%, 83%, 75%, and 0% for stages I, II, III, and IV, respectively. The corresponding figures for MDR were 100%, 82%, 58%, and 40%. Six of the HDR patients (11%) and 2 of the MDR patients (4%) developed Kottmeier's grade 2 or 3 late complications. A DRCF of 0.6 from LDR to MDR could be derived from a DRCF of 0.9 from MDR to HDR and one of 0.54 from LDR to HDR.


CONCLUSIONS
There were no statistically significant differences in cause-specific survival and incidence of late complications between HDR and MDR. A DRCF of 0.6 from LDR to MDR could be determined. However, because the results of this trial were preliminary, a further study is needed.
Tanaka
Eiichi
E
Department of Radiology, Osaka University Graduate School of Medicine, Osaka, Japan. tanaka@radonc.med.osaka-u.ac.jp
Oh
Ryoong-Jin
RJ
Yamada
Yuji
Y
Shiomi
Hiroya
H
Nakamura
Satoaki
S
Shimamoto
Shigetoshi
S
Teshima
Teruki
T
Inoue
Takehiro
T
Inoue
Toshihiko
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D002588:Cesium Radioisotopes / Q000627:therapeutic use*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D009367:Neoplasm Staging; D018570:Risk Assessment / Q000379:methods; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome; D002583:Uterine Cervical Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy*; D014594:Uterine Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000532:radiotherapy
D002588:Cesium Radioisotopes; D007496:Iridium Radioisotopes