Conventional conformal radiotherapy vs intracavitary brachytherapy for the adjuvant postoperative treatment of cervical cancer: a comparative dosimetric study.

OBJECTIVES The aim of this pilot study is to evaluate the feasibility of 3D-conformal radiotherapy (3D-CRT) in the adjuvant postoperative radiotherapy of the vaginal cuff and upper third of present vaginal tissue. METHODS The representative patient (FIGO IB; PH: squamous cell carcinoma) was referred for adjuvant post-hysterectomy radiotherapy. A whole pelvis irradiation with concomitant high-dose-rate intracavitary brachytherapy (HDR-ICBT) was applied. HDR-ICBT total dose of 24 Gy in four fractions/one fraction per week was delivered to the vaginal cuff using two Fletcher-Suit ovoids. The feasibility of change from HDR-ICBT to CRT was evaluated by generating of three different plans using 10 MV photon beams shaped by multileaf collimator. RESULTS AND DISCUSSION The referent volume received HDR-ICBT prescribed dose. The maximum ICBT percentage dose to the rectum and urinary bladder was 101% and 106% respectively. In all 3D-CRT plans almost 100% of planning target volume (PTV) was covered by 95% therapy isodose surface. From 12 - 13% of the rectum and 1-3% urinary bladder volume were covered by 100% isodose surface, with the highest maximum dose of 104% and 101%, respectively. Comparison of the PTV dose coverage and the maximum dose to the rectum and urinary bladder for HDR-ICBT and 3D-CRT plans showed no major difference. CONCLUSION; 3D-CRT could be considered as adequate replacement for ICBT in the adjuvant postoperative treatment of the vaginal cuff and upper thi-rd of present vaginal tissue. Time-dose-fractionation pattern for HDR-ICBT may be safely applied for 3D-CRT.