An analysis of simulation for adjuvant intracavitary high-dose-rate brachytherapy in early-stage endometrial cancer.

PURPOSE The utility of serial simulations in vaginal vault irradiation is controversial. Our primary endpoint was to assess the significance of simulation in women who received adjuvant intracavitary high-dose-rate brachytherapy (HDR-BT) for early-stage endometrial adenocarcinoma. Secondary endpoints included assessment of acute and late treatment toxicity, medication requirements, and charges related to the HDR-BT simulation and procedure. METHODS AND MATERIALS Twenty-four consecutive women with early-stage endometrial cancer treated with adjuvant HDR-BT were evaluated. Descriptive statistical analyses were performed on the ratio of calculated to prescription BT dose at predefined dosimetric points. Data on acute and late toxicities, medication usage, and simulation charges were evaluated and compared. RESULTS The intravaginal cylinder was placed three times over 10-14 days (median 6.5Gy prescribed to 5mm). No substantial deviation in the means of the calculated ratios was observed except at the bladder point (mean 0.77+/-0.23). Early toxicity was found to be no greater than Grade 1 (n=5). Serious late toxicities were uncommon; one woman developed a Grade 3 gastrointestinal toxicity. Half of the women required prescription medication incident to simulation. The average simulation charge was $1252.80. CONCLUSIONS Despite the broad range of doses calculated at the bladder point, genitourinary toxicity was minimal. Simulation proved useful in recording dose and represented a small, yet important portion of the total treatment charge but did not alter treatment in this series. The necessity of simulation for intracavitary high-dose-rate vaginal brachytherapy remains unclear.