Rectal and bladder radiation dose during curative radiotherapy for cervix cancer at Universitas Hospital Oncology.

[摘要] Introduction and aim. Cervical carcinoma is a huge burden on the South Africanpopulation and health care system. Treatment of this disease has improved dramaticallywith the advent of 3D imaging capabilities combined with brachytherapy to deliver dose tothe tumor and limit dose to organs at risk specifically the bladder and rectum. Recentguidelines give recommendations for dose limitations of these organs at risk, specific for avolume of 0.1cc, 1cc and 2cc. Our departmental dose prescription method forbrachytherapy is unique by dose limitation to the rectum for each brachytherapy. The aimof this study was to determine the total dose of combined external beamradiotherapy(EBRT) and brachytherapy to the rectum and bladder for 0.1cc,1cc and 2ccand compare the outcome to international findings.Methods. 57 patients that completed definitive radiotherapy for cervical cancer wereretrospectively reviewed. All patients received EBRT 50Gy in 2Gy daily fractions withbrachytherapy 4-5 doses. The dose normalised to the rectum point receiving the highestdose. The combined dose of EBRT and brachytherapy was converted to bio-equivalentdose in 2Gy fractions (EQD2) for each of the volumes of the rectum and bladder.Results. Mean EQD2 dose to the rectum 0.1cc: 63.8(3.3); 1cc: 60.4(2.2); 2cc: 58.9(1.8).Mean doses to the rectum was lower than described in the literature with no patientreceiving more than the dose cutoff for 2cc(70Gy). Mean doses to the bladder 0.1cc:87.4(18.5); 1cc:75,5(11.9) and 2cc: 71,6(10.0). These doses are also lower as describedin the literature however two patients received dose higher that the advised cutoff to 2cc of90Gy. This could have been avoided for one of the patients if the correct method of dosedetermination was followed.Conclusion. As expected the current dose prescription method yields safe doses to therectum. The bladder dose is a concern even though only two patients exceeded thetolerance and it could have been avoided. High variation in the bladder dose amongpatients suggests an opportunity for dose optimisation techniques. These findings shouldbe correlated with clinical outcomes of toxicity.

[发布机构] University of the Free State