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Indocyanine green technique detects sentinel nodes in breast cancers

Key clinical point: The fluorescent dye indocyanine green tracer showed promise in detecting sentinel lymph nodes in early-stage breast cancer.

Major finding: The dye caused no major side effects and was almost 99% concordant with radioisotope technetium.

Data source: Prospective validation trial evaluating 589 lymph nodes from 301 patients with clinically node-negative, invasive early breast cancer.

Disclosures: The investigators reported no funding sources and no conflicts of interest.


 

FROM THE EUROPEAN JOURNAL OF SURGICAL ONCOLOGY

References

Indocyanine green dye caused no major side effects and was almost 99% concordant with radioisotope technetium for sentinel lymph node detection in early-stage breast cancer, according to researchers.

The results extend promising findings from an earlier meta-analysis of the tracer in a variety of tumor types, said Dr. Domenico Samorani of Santarcangelo di Romagna Hospital, Rimini, Italy.

“The method seems reproducible, safe, eliminates exposure to ionizing radiation, and is potentially cost-saving, despite requiring specialist training. [Also,] it could be an option for breast cancer centers with no nuclear medicine supply,” wrote Dr. Samorani and colleagues.

Sentinel lymph node biopsy has largely replaced axillary lymph node dissection for staging breast cancer, as it causes much less morbidity and is associated with similar rates of survival and locoregional recurrence. Vital blue dyes and radioisotope technetium (99mTc) are the most commonly used enhancers, but the blue dyes can cause allergic reactions and skin necrosis, and 99mTc is costly and requires special logistics and handling because of its radioactivity, the investigators noted. For these reasons, there has been renewed interest in indocyanine green dye (ICG) as an alternative, they said (Eur. J. Surg. Oncol. 2015;41:64-70).

For the study, the investigators evaluated 589 lymph nodes from 301 patients with clinically node-negative, invasive or microinvasive early breast cancer confirmed by core biopsy. All patients underwent 99mTc-guided sentinel node detection, which served as the gold standard for comparison. To perform ICG-guided detection, the researchers diluted 25 mg of ICG PULSION with 5 mL distilled water and then injected empirical doses of 0.4 to 1.2 mL of the solution subcutaneously above the tumor site for unicentric cancers, or around the areola for multicentric disease. Then the researchers used an infrared-emitting camera (Photodynamic Eye, Hamamatsu Photonics, Hamamatsu, Japan) to visualize the lymphatic drainage pathway and localize sentinel nodes for removal.

Overall, 98.7% of sentinel nodes that were 99mTc positive also were ICG positive (95% confidence interval, 97.1%-99.5%), a high degree of concordance that reflected past study results, the investigators said. Notably, the ICG-guided technique identified at least one sentinel node for 297 patients (98.7%), compared with 287 patients (95.4%) for the 99mTc method (P < .05). Thus, the use of ICG prevented removal of the entire axilla for 10 patients, the researchers wrote.

For six patients, the ICG method identified a metastatic node that 99mTc failed to identify. Therefore, ICG provided an advantage for 16 cases (5.3%). No patients experienced allergic reactions, 3.2% developed seromas, and 2.5% developed paresthesia, the researchers added.

Use of ICG instead of 99mTc for sentinel lymph node detection has several advantages: It does not require involving a nuclear medicine department, uses less radioactive material, minimizes issues around waste disposal, and can be performed in the operating room immediately after the induction of general anesthesia, said the researchers. And if combined with radio-guided occult lesion localization (ROLL), it avoids placing two radioactive tracings at the injection site, thereby facilitating tumor detection, the researchers noted.

Clinicians who are implementing ICG-guided sentinel node detection should consider combining it with 99mTc to avoid missing nodes during the learning process, the researchers emphasized.

They reported no funding sources and no conflicts of interest.

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