HYpofractionated Pelvic Radiotherapy for Advanced Cervical Cancers INeligible for ChemoTherapy

BACKGROUND: For patients with locally advanced cervical cancer (LACC) ineligible for concurrent chemotherapy, radiotherapy (RT) alone achieves complete response rate (CRR) \<70% and long-term locoregional control (LRC) \<62%. Hypofractionated (HF-)RT using older techniques results in comparable CRR and disease control, and low late toxicity rates (4-8%). Dose-adapted HF-RT using intensity-modulated radiotherapy (IMRT) with nodal simultaneous integrated boost (nSIB) could improve tumor control and toxicity.

GENERAL OBJECTIVE: To determine the effectiveness and safety of HF-RT with (or without) nSIB in LACC among patients who are chemo-ineligible.

PRIMARY OBJECTIVES:

Phase 1: To determine the maximum tolerated dose (MTD) for nSIB used in combination with pelvic HF-RT (2.67 Gray (Gy) x 15 fractions), using IMRT Phase 2: To assess the efficacy of HF-RT ± nSIB in terms of complete response rates at 3 months

SECONDARY OBJECTIVES:

To assess the efficacy of HF-RT ± nSIB in terms of progression free survival (PFS), locoregional PFS, distant metastasis free survival (DMFS), cervical cancer specific survival (CCSS), overall survival (OS)

To assess the acute and late toxicity of HF-RT ± nSIB, and patient-reported quality of life outcomes

EXPLORATORY OBJECTIVES:

To evaluate the predictive utility of clinical and dosimetric variables for tumor response/control and toxicity. Variables: age, performance status, T- and N-stage, T-score, histology, baseline hemoglobin, clinical target volume and organs-at-risk doses, overall treatment time

STUDY DESIGN:

Phase 1: Dose-escalation study (standard 3+3 design) Phase 2: Single-arm clinical trial (Simon's two-stage design)

STUDY TREATMENTS:

Pelvic HF-RT ± nSIB to 40 Gy in 15 fractions using IMRT, followed by brachytherapy (BRT) 6.5-7.5 Gy x 4 fractions using 2D or image-guided techniques

SAMPLE SIZE:

One-sided hypothesis testing. H0: CRR p0 ≤64%; H1: CRR p1 ≥84%. Simon 2 stage: First stage, n1=28 will be enrolled. If response (r1) ≤18, the study will be stopped for futility. Otherwise, second stage: n2=22, for a total of 50.

H0 will be rejected if r1+r2 ≥38, in 50 patients. This yields a type I error rate of 5% and power of 95% when the true response rate is ≥84%.

Accrual: Accounting for 10% attrition, a n=55 will be targeted. At a rate of 4-5 patients quarterly, accrual may take 33-42 months. The trial may be opened to other centers to accelerate accrual.