Aim: To analyze the influence of computed tomography (CT)-guided 3D conformal interstitial brachytherapy (3D-IBT) boost for better coverage of target volumes and study the diametric impact to organ at risk in patients with post-surgery recurrent and residual cervical cancer.
Material and Methods: Fourteen consecutive patients with recurrent or residual cervical cancer who were treated with interstitial brachytherapy as a boost were included in the study. All patients received 50.4 Gy external radiation (EBRT) to whole pelvis with conformal technique to reduce the dose to bowel. The clinical target volume (CTV) and organs at risk were contoured on CT scan with gold seeds being a surrogate marker of initial tumor extent implanted before commencing treatment. The median dose of prescription was 10.5–12 Gy in 3 fractions. Dose volume histogram was calculated to evaluate the dose that covers 100% and 90% of the target volume and dose to the bladder, rectum and bowel (2 mL, 1 mL volume).
Results: The median follow-up was 12 months (range 6–18). The doses to CTV (D90, D100) ranged from 1141 to 2014 cGy, and 585 to 969 cGy, respectively. The mean cumulative 2-mL rectal, bladder and bowel doses were 66.70, 73.15 and 61.01 Gy, respectively. Rectal toxicity of grade 2 or more had a strong correlation with the dose delivered (Spearman's correlation, 0.950). The local control rate at one year was 92% with failure seen in one patient only.
Conclusion: Conformal EBRT supplemented with 3D-IBT seems to be a practical and appropriate approach to give the most optimal therapeutic benefit with the least side-effects in postoperative recurrent and residual cervical cancer patients.