Local control and toxicity results in cervical cancer patients treated with 3d conformal brachytherapy

BRT is an essential option in the treatment of locally advanced cervical cancer. In order to assess the doses of the tumor and OAR, ICRU reference points are used. Studies have shown that this indirect evaluation fails to be true more often than not; tumor doses are overestimated while OAR doses are underestimated. With conformal BRT, it is possible to see the dose distribution in tumor and OAR. Evaluating the effect of DVH parameters regarding tumor and OAR on local control and late toxicities due to RT was aimed in this study. Of the patients referred to Başkent University Deparment of Radiation Oncology with stage IB-IVA cervical cancer between January 2008 – May 2011, 55 patient treated with 3 dimensional conformal brachytherapy were included for assessment. After a mean follow-up of 20.7 months, 2 year actuarial overall survival(OS) and LC were 62.4% and 84.8%, respectively. GTV and CTV are significantly larger in patients with recurrence (p=0.04). DVH parameters for GTV, D100 (the minimum dose received by 100% of the target volume) and D90 were higher in the patients who achieved local control (p<0.001). CTVD100, D98, D90 and D50 doses were not found to be significant for local control. Late gastrointestinal system (GIS) and genitourinary system (GUS) toxicity was seen in 23 (41.8%) patients. 11 (20%) patients had grade 3-4 GIS toxicity and 2 patients (3.6%) had grade 3 GUS toxicity. In patients with late GIS toxicity, rectum D0.1cc ( the minimum dose received by 0.1cc), D1cc and D2cc doses were significantly higher than the patients without toxicity(p=0.04, p=0.02, p=0.01, respectively). GTV, CTV and OAR DVH parameters have clinical significance in prediction of LC and treatment related toxicity. With experience in dose optimisation, maintaining high CTV doses while decreasing OAR doses will result in high LC rates with low toxicity in brachytherapy planning.