Background: The standard treatment for locally advanced cervical cancer (LACC) is concurrent chemoradiation (CRT) followed by brachytherapy (BRT). The addition of chemotherapy (ChT) to radiotherapy (RT) is associated with a 7.5% improvement in overall survival but with more grade 3-4 acute toxicities (16.4% vs 4.9%, CRT vs RT alone). The risk-benefit ratio could be less favorable in advanced disease with renal dysfunction secondary to tumor-related hydronephrosis; borderline cardiac function; and frail patients. RT alone followed by BRT achieves long-term locoregional control <62%. Hypofractionated RT (HF-RT) using older techniques result in comparable disease control and low late toxicity rates (4-8%). Dose-adapted HF-RT using intensity-modulated RT with nodal simultaneous integrated boost (nSIB) could improve tumor control and toxicity, when ChT is contraindicated.
Methods: The HYACINCT study is a two-phase study to determine the effectiveness and safety of HF-RT with nSIB in LACC when ChT is contraindicated. Phase 1 is a dose-escalation study using standard 3 + 3 design, to determine the maximum tolerated dose (MTD) for nSIB in combination with pelvic HF-RT (2.67 Gy x 15 fractions). Phase 2 is a single-arm clinical trial using Simon's two-stage design, to assess the efficacy of HF-RT with nSIB in terms of tumor response. Adult women with biopsy-proven, untreated LACC, with contraindication to ChT will be included in this trial.
Discussion: For the phase 1, the primary endpoint is dose-limiting toxicity (DLT), or any grade ?3 acute or sub-acute toxicity. The dose level at which incidence of DLT is ?33% is defined as the maximum tolerance dose (MTD). For the phase 2, the primary endpoint is complete response at 3 months post-treatment. Secondary outcomes are progression-free and overall survival, acute and late toxicity, and patient-reported outcomes (EPIC, EORTCQLQ C30 + CX24, PGIC, PCIS). Trial registration: NCT05210270.
Keywords: Cervical cancer; hypofractionation; intensity-modulated radiotherapy; nodal boost; simultaneous integrated boost.