Integration of Multi-modality Imaging Protocols With emphAsis on CT in Image Guided Adaptive Brachytherapy (IGABT) for Cervical Cancer - EMBRACE III-IMPACT STUDY

Title: Integration of Multi-modality Imaging Protocols with Emphasis on CT in Image-Guided Adaptive Brachytherapy (IGABT) for Cervical Cancer - EMBRACE III-TRIPLET : IMPACT Study Locally advanced cervical cancer (LACC) remains a major health challenge, particularly in low- and middle-income countries (LMICs), which account for the majority of global cases. The standard curative treatment involves a combination of external beam radiotherapy (EBRT) with concurrent chemotherapy, followed by brachytherapy (BT). Brachytherapy plays a crucial role in achieving high local control by delivering radiation directly to the tumour through internally placed radioactive sources.

Historically, BT dose prescription was based on two-dimensional (2D) X-ray images and defined anatomical "points," achieving 5-year local control rates of 60-70%. Over the last decade, magnetic resonance imaging (MRI)-based image-guided adaptive brachytherapy (MR-IGABT) has transformed practice by enabling three-dimensional (3D) target-based dose prescription and adaptation to tumour regression. The landmark EMBRACE I study, involving over 1300 patients, demonstrated over 90% 5-year local control rates with MR-IGABT, establishing it as the international gold standard endorsed by NCG, ICRU, NCCN, and ESGO-ESTRO guidelines.

However, MRI-based planning for IGABT remains logistically and financially challenging for many centres, especially in LMICs. CT and transrectal ultrasound (TRUS) have emerged as feasible alternatives, offering broader accessibility. Despite encouraging outcomes from smaller institutional studies, the lack of standardized and validated target delineation concepts for CT-IGABT has led to significant variability in clinical implementation. Recognizing this, the Indian Brachytherapy Society (IBS), American Brachytherapy Society (ABS), and GEC-ESTRO jointly published consensus recommendations in 2020 to standardize CT-IGABT practices across diverse clinical environments.

At Homi Bhabha Cancer Hospital and Research Centre, Visakhapatnam, our prior work (RetroLACER Study) demonstrated that CT-based IGABT can achieve outcomes comparable to MR-IGABT, highlighting its feasibility and potential for wider adoption. Building on this foundation, the EMBRACE III-IMPACT Study seeks to evaluate whether CT-IGABT can be systematically and uniformly implemented in a multi-centre setting and to benchmark clinical outcomes against the standards set by MR-IGABT.

Study Design:

This is a multicentre, prospective, observational study planned to include approximately 1200 participants with locally advanced cervical cancer. All participants will receive standard-of-care treatment, including EBRT, concurrent weekly cisplatin chemotherapy, and brachytherapy with image-guided planning.

Objectives:

To assess the feasibility of implementing standardized CT-IGABT protocols across diverse clinical environments.

To evaluate local control, disease-free survival, and treatment-related toxicity outcomes for CT-IGABT.

To compare and benchmark CT-IGABT outcomes with established MR-IGABT benchmarks from prior international studies.

Participant Involvement:

Participants will undergo standard diagnostic imaging, EBRT with weekly cisplatin, and brachytherapy using CT-based planning. Imaging and treatment data will be collected, anonymized, and submitted to a central database for review. Regular follow-up visits will monitor tumour control and treatment-related side effects.

Benefits:

Participants receive internationally standardized, quality-assured treatment protocols. Centres gain access to expert review and QA support from international collaborators, potentially improving treatment quality and outcomes.

The study supports global efforts to establish CT-IGABT as a cost-effective, accessible alternative to MRI-based IGABT, expanding equitable cancer care access.

Risks:

The study is observational and involves standard treatment; therefore, risks and costs are comparable to routine cervical cancer care.

Confidentiality and Ethics:

All data will be anonymized and handled in compliance with ethical and regulatory standards. Participant confidentiality will be strictly maintained. Written informed consent will be obtained before study participation.

Significance:

By validating standardised CT-based protocols and establishing outcome benchmarks, the study aims to facilitate widespread adoption of IGABT in resource-limited settings, ultimately improving treatment accessibility and survival outcomes.