High-dose-rate interstitial computed tomography-based brachytherapy for the treatment of cervical cancer: early...

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.

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 45Gy and all had one interstitial implantation followed by 3.75-5Gy×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 2Gy per fraction. At 3 months posttherapy, early response was assessed with clinical examination and positron emission tomography (PET/CT) imaging.

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 2cc 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.

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.