Comparison of tumor regression rate of uterine cervical squamous cell carcinoma during external beam and intracavitary radiotherapy.
OBJECTIVE
We compared the radioresponse of cervical carcinoma that was closely related to local disease control by the tumor regression rate (RR) during intracavitary radiotherapy (ICRT) and external beam radiotherapy (EBRT) on the presumption that ICRT has a stronger treatment impact than EBRT because of its specific dose distribution.


METHODS
A total of 37 patients were treated by EBRT at 45.0 Gy over 5 weeks, followed by high-dose-rate ICRT at 6.0 Gy per weekly insertion at point A three to five times and by boost EBRT. RR was defined as the slope (day(-1)) of the tumor-volume shrinkage curve fit to an exponential regression equation. Assuming that the tumors were ellipsoid, the tumor volume was estimated using magnetic resonance (MR) images obtained before treatment, after 45.0 Gy of EBRT, and after the third ICRT insertion. RRs were compared based on the radiotherapy method.


RESULTS
RR ranged between -0.008 to 0.093 day(-1) (median 0.021 day(-1)) during EBRT and -0.001 to 0.097 day(-1) (median 0.018 day(-1)) during ICRT, showing no significant difference or correlation between treatments.


CONCLUSIONS
Contrary to expectations, RR did not directly relate to the impact of physical treatment. RR could be related to biological factors, such as the amount of tumor clearance and changes in tumor consistency during treatment.
Ohara
Kiyoshi
K
Department of Radiation Oncology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan. ki-ohara@md.tsukuba.ac.jp
Tanaka
Yumiko Oishi
YO
Oki
Akinori
A
Okamoto
Yoshikazu
Y
Satoh
Toyomi
T
Matsumoto
Koji
K
Yoshikawa
Hiroyuki
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001918:Brachytherapy / Q000379:methods*; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D002583:Uterine Cervical Neoplasms / Q000473:pathology* / Q000532:radiotherapy*