Magnetic Resonance Image Guided Adaptive Brachytherapy in Locally Advanced Cervical Cancer: An Experience From a Tertiary Cancer Center in a Low and Middle Income Countries Setting.

Abstract

To determine the clinical impact of magnetic resonance image guided adaptive brachytherapy (IGABT) for locally advanced cervical cancer (LACC) (stages II and III) in a tertiary care cancer hospital in a low and middle income countries setting. Ninety-four LACC patients enrolled in a prospective EMBRACE (An International Study on MRI-Guided Brachytherapy in Locally Advanced Cervical Cancer) protocol treated with external radiation therapy (45 Gy in 25 fractions) with or without weekly cisplatin, followed by magnetic resonance IGABT (4 fractions of 7 Gy), were analyzed in detail for dosimetric and clinical outcomes including late toxicities. The mean (± standard deviation) high-risk clinical target volume (HR-CTV) at the first session of brachytherapy and at the second session of brachytherapy for the current study cohort was 46.94 ± 24.6 cm³ and 42.7 ± 22.5 cm³, respectively, with mean minimum dose received by 90% volume (D₉₀) of 88.3 ± 4.4 equivalent 2-Gy fractionation (Gy_EQD2). At median follow-up (39 months), the local control rate (LCR) and overall progression-free survival rate were 90.1% ± 3.4% and 72.1% ± 4.8%, respectively, with grade 3 bladder toxicity in 3% of patients and rectum toxicity in 9%. The LCR at 39 months was significantly better in patients with stage IIB and IVA disease versus stage IIIB disease (100% vs 85%, P=.013). Local failures were limited to stage IIIB only and were associated with significantly larger HR-CTVs at brachytherapy (70 ± 25.7 cm³ vs 44.3 ± 21.9 cm³, P=.01) but not with HR-CTV D₉₀ doses (which were similar for patients who had local failures vs those who did not: 86.3 ± 3.9 α/β equal to 10 Gy (Gy₁₀) vs 88.5 ± 5 α/β equal to 10 Gy, P=.987). IGABT leads to a significant improvement in LCR and overall progression-free survival in LACC and should be considered for wider implementation in developing countries to improve outcomes.