Clinical outcomes using image-guided interstitial brachytherapy for definitive cervical cancer patients with high-risk clinical target volumes greater than 30 cc

PurposeGiven the limited data using an interstitial approach with 3D-based planning for definitive cervical cancer utilizing the GEC-ESTRO defined high-risk clinical target volume (HR-CTV), we reviewed our institutional experience of cervical cancer patients with HR-CTVs ≥ 30 cc to determine whether our clinical and toxicity outcomes are acceptable.MethodsA retrospective review of 37 cervical cancer patients with high-risk clinical target volumes (HR-CTVs) ≥30 cc treated with interstitial image-guided brachytherapy (IS IGBT) was performed. All patients received external beam radiotherapy to a median dose of 45 Gy, followed by IS IGBT delivered in a single implant to a median dose of 6 Gy × 5 fractions. Median HR-CTV was 59 cc. A median HR-CTV D₉₀ of 87.44 Gy was achieved. Kaplan–Meier method was used to evaluate local control (LC), distant control, and overall survival (OS), with stratification by overall treatment time (OTT) ≤ 7 or >7 weeks.ResultsMedian followup was 17 months. The estimated 2-year LC, distant control, and OS were 77.6% (confidence interval [CI]: 63.8–94.5%), 56.8% (CI: 41.3–78.1%), and 54.4% (CI: 39.4–75%), respectively. The 2-year LC for OTT ≤7 weeks and >7 weeks were 100% and 58.3%, respectively (p = 0.026). The 2-year OS for OTT ≤7 weeks and >7 weeks were 77.8% and 38%, respectively (p = 0.021).DiscussionsIS IGBT can achieve a high D₉₀ to the HR-CTV even in the setting of large-volume disease and results in a favorable LC and toxicity profile. OTT > 7 weeks is associated with significant decrease in LC and OS.ConclusionsEfforts should be made to complete whole treatment within 7 weeks as this is associated with improved clinical outcomes.