High-dose-rate interstitial computed tomography–based brachytherapy for the treatment of cervical cancer: Early results

Abstract Purpose There is limited published data on high-dose-rate interstitial brachytherapy (HDRBT) for cervical cancer resulting in no consensus on a fractionation schedule. This study reports our experience of CT-based HDRBT for treating locally advanced cervical cancer. Methods and Materials Forty-seven patients diagnosed with Stage IIB–IVA cervical cancer not suitable for intracavitary brachytherapy were treated with HDRBT from March 2005 to November 2010. All patients received external beam radiation therapy with a median dose of 45 Gy and all had one interstitial implantation followed by 3.75–5 Gy × 5 fractions in a twice daily (BID) schedule. Total doses for clinical target volume and organs at risk, including rectum, bladder, and sigmoid, were summated and normalized to a biologically equivalent dose of 2 Gy per fraction. At 3 months posttherapy, early response was assessed with clinical examination and positron emission tomography (PET/CT) imaging. Results Median clinical target volume D 90 (dose delivered to 90% of the clinical target volume) was 76.3 (59.0–86.9) Gy and the 2 cc dose to the bladder, rectum, and sigmoid colon organs were 70.2 (55.9–77.7), 65.8 (54.9–80.6), and 56.5 (45.0–71.2) Gy, respectively. Posttreatment, 12 patients had evidence of persistent disease on PET/CT. Eleven of the 35 patients who had complete response developed recurrences. Two patients developed late Radiation Therapy Oncology Group ≥3 rectal toxicities. Two-year actuarial local control, disease-free survival, overall survival, and Grade ≥3 toxicities were 61%, 43%, 59%, and 10%, respectively. Conclusion Our approach of a single implantation procedure followed by five fractions of HDRBT was well tolerated with early results demonstrating a moderate response and local control rate with acceptable toxicities.