Fluorescence imaging using indocyanine green to identify sentinel lymph nodes during surgery for breast cancer (INFINITE): protocol for a hybrid effectiveness-implementation trial using a stepped-wedge cluster design

Introduction Sentinel lymph node biopsy (SLNB) is the standard procedure for axillary staging in clinically node-negative breast cancer. Traditionally, SLNB is performed using technetium-labelled ( 99m Tc) nanocolloid, with or without blue dye.

However, both tracers have important limitations. Blue dye poses safety risks, while 99m Tc-nanocolloid introduces additional hospital visits, radiation exposure, logistical complexity and high costs.

Indocyanine green (ICG) fluorescence is a non-radioactive alternative, offering real-time visualisation while addressing many limitations of traditional tracers. Yet, adoption of ICG-guided SLNB remains limited.

This trial aims to guide the implementation of ICG-guided SLNB via axillary incision, evaluate its real-world effectiveness and inform conditions for nationwide scale-up. Methods and analysis The INFINITE trial is a multicentre, hybrid effectiveness-implementation study employing a stepped-wedge cluster design across seven Dutch hospitals.

Clusters sequentially transition from SLNB using 99m Tc-nanocolloid alone (Phase I) to ICG as the primary tracer and 99m Tc-nanocolloid as a within-patient control (Phase II), and finally to ICG alone (Phase III).