See Better During Surgery: How a Special Dye Can Highlight Hidden Cancer
"A new technique uses a fluorescent dye to help surgeons find and remove hard-to-detect metastatic lesions, potentially improving outcomes and reducing the need for extensive surgery."
Surgical oncology constantly seeks methods to improve the precision and effectiveness of tumor removal, aiming to increase patient survival rates and reduce recurrence. A significant challenge lies in locating and removing metastatic lesions, particularly small ones, which can be difficult to detect using standard imaging techniques such as PET, MRI, or CT scans. This is especially crucial in recurrent cancers where previous treatments may have altered the anatomical landscape, making lesion identification even more complex.
To address this challenge, a novel approach has been developed using indocyanine green (ICG), a fluorescent dye, in conjunction with computer tomography (CT) guidance. This technique involves injecting ICG directly into suspected metastatic lesions, allowing surgeons to visualize them more clearly during laparoscopic surgery using near-infrared (NIR) imaging. The dye effectively highlights the lesions, distinguishing them from surrounding healthy tissue and enabling more precise removal.
This article explores the innovative application of ICG in mapping metastatic lesions, detailing how it enhances surgical accuracy, potentially minimizes the extent of surgery required, and improves patient outcomes. By providing a clear, real-time visual guide, this technique promises to transform the surgical management of metastatic cancers, offering a more targeted and less invasive approach.
Current Surgical Approaches
Conventional cancer surgery may be used alongside systemic therapy, but the benefit of primary-site surgery in metastatic cancer varies by cancer type and remains uncertain in some settings. A Cochrane meta-analysis of two randomized trials in metastatic breast cancer found the overall-survival benefit of surgery unclear because of low-quality evidence. In contrast, an October 14, 2025 systematic review reported that ICG-guided surgery for gastric cancer was associated with improved short- and mid-term overall survival, enhanced lymph-node retrieval, and reduced intraoperative blood loss without increasing postoperative complications, operative time, or hospital stay.
The ICG Technique: A Step-by-Step Guide
The method involves a coordinated effort between radiologists and surgeons, utilizing CT imaging to precisely guide the injection of ICG into suspected metastatic sites. Here’s a detailed breakdown of the process:
- Initial Imaging: Patients undergo a conventional CT scan with contrast to identify and delineate suspected metastatic lesions. This step is crucial for planning the subsequent ICG injection.
- ICG Preparation: A vial of 25 mg ICG powder is mixed with 5 ml of sterile water to achieve maximum concentration. The goal is to use the smallest amount of ICG necessary to effectively mark the lesion.
- CT-Guided Injection: Using a 20-Gauge needle, radiologists inject 0.2-0.3 ml of the ICG solution directly into the targeted lesion under CT guidance. Real-time imaging ensures accurate placement of the dye.
- Surgical Procedure: The patient is then transferred to the operating room, where a laparoscopic procedure is performed using a near-infrared (NIR) camera. The NIR camera detects the fluorescence emitted by the ICG, causing the marked lesion to appear as a distinct blue spot, clearly differentiated from the surrounding tissue.
- Lesion Resection: Guided by the NIR visualization, surgeons precisely remove the marked lesion. This targeted approach helps to spare healthy tissue, reducing the morbidity associated with more extensive resections.
- Pathological Confirmation: The resected tissue is sent for pathological analysis to confirm the presence of metastatic cells and ensure accurate diagnosis.
Expanding Fluorescence Uses
Recent work has examined fluorescence and dye-based methods beyond a single surgical application. A review of indocyanine green in gynecologic oncology describes uses including lymphography, angiography, nerve visualization, ICG-driven resections, and theranostics. In one report cited by that review, all lesions were successfully identified and resected, while a separate study of methylene blue mixed with autologous blood for preoperative localization of pulmonary nodules and masses reported an overall complication rate of 2.65%, with no special treatment required.
Limits and Complications
The evidence also includes technical limitations and procedure-related risks. A case series on computed tomography-guided percutaneous ICG injection for intraoperative mapping of suspected metastatic lesions acknowledged limitations in its design and described its findings as a possible basis for establishing a new procedure rather than definitive evidence. In another report, a metastatic lymph node had infiltrated the external iliac vein, causing high blood loss and requiring vascular interposition, while studies of near-infrared fluorescence continue to evaluate how accurately ICG can demarcate tumors and predict resection-margin status.
ICG Versus Conventional Surgery
Comparative studies have evaluated whether ICG improves lymph-node harvesting during laparoscopic gastric-cancer surgery. A March 5, 2025 prospective non-randomized study used 1:1 propensity-score matching to compare ICG lymphography with a non-ICG approach during laparoscopic radical distal gastrectomy. A separate October 14, 2025 systematic review reported that ICG-guided gastric-cancer surgery was associated with enhanced lymph-node retrieval, lower intraoperative blood loss, and improved short- and mid-term overall survival without higher postoperative complications, operative time, or hospital stay.
The Future of Precision Surgery
The use of ICG in conjunction with CT-guided injection represents a significant advancement in the surgical management of metastatic cancers. This technique offers improved visualization, enhanced precision, and the potential for less invasive procedures, ultimately leading to better outcomes for patients. As hybrid operating theaters become more prevalent, the integration of such technologies will likely become standard practice, transforming the landscape of surgical oncology. While the initial case series demonstrates promising results, further research and broader clinical application will solidify its role in optimizing cancer surgery.
Where Fluorescence May Go Next
Future research is examining how fluorescence-guided surgery could be applied across more cancers and procedures. A 2026 review synthesizes evidence on how surgery may affect cancer metastasis through perioperative inflammation, immune alterations, circulating tumor cells, epithelial–mesenchymal transition, tumor dormancy, and mechanisms involving neutrophil extracellular traps. The American College of Surgeons reports that expanding laparoscopic and robotic-assisted surgery is creating opportunities to use fluorescence-guided surgery beyond oncology, while clinical studies of pafolacianine and ICG have reported improved detection of metastatic lesions during ovarian, hepatic, and thoracic oncologic surgery.
From Imaging to Surgical Practice
Real-world studies are evaluating whether ICG fluorescence can help surgeons sort or identify lymph nodes during cancer operations. A case series examined real-time ICG imaging for lymph-node sorting during radical esophagectomy for esophageal cancer and included specimens from 66 patients who underwent esophageal-cancer resection with lymph-node dissection between August 2022 and June 2023. Another report described ICG accumulation in hepatocellular-carcinoma cells and its use in detecting metastatic lesions, including metachronous lymph nodes that can be difficult to identify during salvage surgery after previous operations.