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Researchers reviewed evidence on various tracers for sentinel lymph node biopsy in endometrial cancer and identified the most effective combination.
A new study evaluating various tracer combinations for sentinel lymph node (SLN) biopsy in endometrial cancer (EC) highlighted the superior performance of a dual-tracer approach using 99mTc and indocyanine green (ICG). The authors published results from their network meta-analysis in the International Journal of Surgery.
“According to the International Federation of Gynecology and Obstetrics staging system, pathological information regarding the primary tumor and lymph node status guides the choice of adjuvant therapy and prognosis for patients with endometrial cancer,” Chuanli Feng and colleagues wrote. “Through comparisons of the total detection rate, bilateral detection rate, and para-aortic detection rate across multiple tracer combinations, we aimed to identify an optimal tracer combination that could enhance the detection rate of SLN in EC and facilitate the early identification of metastatic disease.”
Despite its ability to provide detailed lymph node information, systematic lymphadenectomy is associated with increased risks of surgical complications. It has not been shown to improve survival outcomes, particularly in patients with low-risk EC.
In contrast, SLN biopsy has emerged as a safer alternative, offering a less invasive method while reducing the collateral damage associated with more extensive lymphadenectomy procedures. Accurate identification of the SLN is crucial for determining metastatic spread, and the choice of tracer used in the biopsy can significantly influence detection rates and surgical outcomes.
Types of Tracers
SLN biopsy methods typically involve two main approaches: dye-based staining and radioisotope tracking.
Dye-based tracers, such as indocyanine green (ICG), are widely used because they can provide real-time visual feedback during surgery, particularly through fluorescence under near-infrared light.
ICG is a popular choice because of its high sensitivity and specificity. Other dyes, including patent blue and carbon nanoparticles (CNPs), offer distinct advantages in terms of rapid visualization and deeper tissue penetration. However, they have certain risks, such as allergic reactions or potential lymphatic edema.
On the other hand, radioisotope tracers, particularly technetium-99m (99mTc), provide preoperative lymphatic mapping through nuclear imaging, which aids in more precise surgical planning but adds complexity and cost. Combining different tracers, such as ICG with 99mTc, has shown promise in improving detection rates.
Tracer Combination Shows Efficacy in EC
The study authors employed a comprehensive search strategy, encompassing databases like Cochrane, PubMed, Web of Science, Embase, and Clinicaltrials.gov, including literature from inception to January 2024. Two independent authors conducted the data extraction and a third resolved discrepancies. Statistical analysis, including Bayesian network meta-analysis, was performed using Stata17 and R software, ensuring consistency and ranking the efficacy of different interventions based on SUCRA scores.
The researchers analyzed 11 studies involving 2,699 participants. They compared seven tracer combinations, including ICG, 99mTc+ICG, blue dye, and CNPs.
The total detection rate analysis showed that ICG significantly outperformed blue dye, with low statistical heterogeneity across most comparisons, except for the 99mTc+ICG vs ICG group. In terms of bilateral detection rates, ICG was more effective than 99mTc, blue dye, and 99mTc+blue, while the combination of 99mTc+ICG showed better detection rates than other tracers. Statistical heterogeneity remained small for most comparisons, except for 99mTc+ICG vs ICG.
The network meta-analysis confirmed that ICG, 99mTc+ICG, and 99mTc+blue had the highest detection rates for SLN biopsy, with 99mTc+ICG ranking highest according to the SUCRA score. ICG also showed significant efficacy in bilateral detection rates, especially when compared to blue dye and 99mTc+blue, with 99mTc+ICG performing best.
“Our results indicate that all interventions in this network meta-analysis have positive impacts on SLN detection, with the 99mTc and ICG combination showing particular efficacy,” the authors concluded. “The tissue penetration capability of ICG, coupled with the stabilizing effect of 99mTc on ICG, indeed enhances the accuracy of SLN biopsy… It is their complementary characteristics that make their combination clinically practical and provide the basis for our research findings.”
The review authors recommended further research to confirm the tracer combination’s effectiveness across all clinical scenarios.
