Dose equivalence for high-dose-rate to low-dose-rate intracavitary irradiation in the treatment of cancer of the uterine cervix.
By comparing the incidence of major radiation injury, we estimated doses clinically equivalent for high-dose-rate (HDR) to conventional low-dose-rate (LDR) intracavitary irradiation in patients with Stages IIb and IIIb cancer of the uterine cervix. We reviewed a total of 300 patients who were treated with external beam therapy to the pelvis (50 Gy in 5 weeks) followed either by low-dose-rate (253 patients) or high-dose-rate (47 patients) intracavitary treatment. The high-dose-rate intracavitary treatment was given 5 Gy per session to point A, 4 fractions in 2 weeks, with a total dose of 20 Gy. The low-dose-rate treatment was given with one or two application(s) delivering 11-52 Gy to the point A. The local control rates were similar in both groups. The incidence of major radiation injury requiring surgical intervention were 5.1% (13/253) and 4.3% (2/47) for low-dose-rate and high-dose-rate groups, respectively. The 4.3% incidence corresponded to 29.8 Gy with low-dose-rate irradiation, thus, it was concluded that the clinically equivalent dose for high-dose-rate irradiation was approximately 2/3 (20/29.8) of the dose used in low-dose-rate therapy.
Akine
Y
Y
Department of Radiation Therapy, National Cancer Center Hospital, Tokyo, Japan.
Tokita
N
N
Ogino
T
T
Kajiura
Y
Y
Tsukiyama
I
I
Egawa
S
S
D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects; D005260:Female; D006801:Humans; D008875:Middle Aged; D011832:Radiation Injuries / Q000209:etiology; D011879:Radiotherapy Dosage; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*