Prospective evaluation of factors influencing success rates of sentinel node biopsy in 814 breast cancer patients

The combination of blue dye and radioisotope versus radioisotope alone during sentinel lymph node biopsy for breast cancer: a systematic review

Background

The combination of blue dye and radioisotope is most widely used to identify sentinel lymph nodes (SLNs) in patients with breast cancer. However, some individual studies suggested that dual tracers did not have an advantage over radioisotope alone in detecting SLNs. We performed a systematic review to investigate the added value of blue dye in addition to radioisotope.

Methods

We searched Pubmed and Embase. Prospective studies that compared the combination of radioisotope and blue dye with radioisotope alone were selected. The identification rate of SLNs and the false-negative rate were the main outcomes of interest. The odds ratios (ORs) and 95 % confidential intervals (CIs) were calculated by using random-effects model.

Results

Twenty-four studies were included. The combination of radioisotope and blue dye showed higher identification rate than radioisotope alone (OR = 2.03, 95 % CI 1.53–2.69, P < 0.05). However, no statistically significant difference was revealed for patients after neoadjuvant chemotherapy (OR = 1.64, 95 % CI 0.82–3.27, P > 0.05), or for studies with high proportion of patients with positive lymphoscintigraphy (OR = 1.41, 95 % CI 0.83–2.39, P > 0.05). Dual tracers did not significantly lower the false-negative rate compared with radioisotope alone (OR = 0.76, 95 % CI 0.44–1.29, P > 0.05).

Conclusions

Although the combination of blue dye and radioisotope outperformed radioisotope alone in SLN detection, the superiority for dual tracers may be limited for patients with positive lymphoscintigraphy or for those after neoadjuvant chemotherapy. Besides, the combined modality did not help lower the false-negative rate.

Blue dye is sufficient for sentinel lymph node biopsy in breast cancer

BACKGROUND

Most previous studies have reported superior results when blue dye and radiocolloids were used together for sentinel lymph node (SLN) biopsy in early breast cancer. Blue dye was reported to perform poorly when used alone, although more recent studies have found otherwise. This study reviewed the authors' practice of performing SLN biopsy with blue dye alone.

METHODS

This was a retrospective review of patients who underwent SLN biopsy using blue dye alone from 2001 to 2005, when SLN biopsy was performed selectively and always followed by axillary lymph node dissection (ALND), and from 2006 to 2010, when SLN biopsy was offered to all suitable patients and ALND done only when the SLN was not identified or positive for metastasis.

RESULTS

Between 2001 and 2005, 170 patients underwent SLN biopsy with blue dye alone. The overall SLN non-identification rate was 8·4 per cent. The overall false-negative rate was 34 per cent, but decreased with each subsequent year to 13 per cent in 2005. From 2006 to 2010, 610 patients underwent SLN biopsy with blue dye alone. The SLN was not identified in 12 patients (2·0 per cent) and no significant contributing factor was identified. A median of 2 (range 1-11) SLNs were identified. A non-SLN was found to be positive for metastasis in two patients with negative SLNs. Axillary nodal recurrence developed in one patient; none developed internal mammary nodal recurrence. Anaphylaxis occurred in one patient.

CONCLUSION

Blue dye performed well as a single modality for SLN biopsy. Non-identification, axillary nodal recurrence and serious allergic reactions were uncommon.

Imaging tumor-induced sentinel lymph node lymphangiogenesis with LyP-1 peptide

Lymphangiogenesis in tumor-draining lymph nodes (LNs) starts before the onset of metastasis and is associated with metastasis to distant LNs and organs. In this study, we aimed to visualize tumor-induced lymphangiogenesis with a tumor lymphatics-specific peptide LyP-1. The LyP-1 peptide was labeled with a near-infrared fluorophore (Cy5.5) for optical imaging. At days 3, 7, 14 and 21 after subcutaneous 4T1 tumor inoculation, Cy5.5-LyP-1 was administered through the middle phalanges of the upper extremities of the tumor-bearing mice. At 45 min and 24 h postinjection, brachial LN fluorescence imaging was performed. Ex vivo fluorescence images were acquired for quantitative analysis of the fluorescence intensity. Tumor-induced lymphangiogenesis was confirmed by LYVE-1 immunostaining and increased size of tumor side brachial LNs. Cy5.5-LyP-1 staining in LNs co-localized with LYVE-1, suggesting lymphatics-specific binding of LyP-1 peptide. The brachial LNs were clearly visualized by optical imaging at both time points. The tumor side LNs showed significantly higher fluorescence intensities than the contralateral brachial LNs at days 7, 14, and 21, but not day 3 after tumor inoculation. At day 21 after tumor inoculation, the average signal of tumor-draining LNs was 78.0±2.44, 24.3±5.43, 25.6±0.25 (×10(3) photon/cm2/s) using Cy5.5-LyP-1, Cy5.5-LyP-1 with blocking, and Cy5.5 only, respectively. Tumor-draining brachial LNs showed extensive growth of lymphatic sinuses throughout the cortex and medulla. Use of LyP-1 based imaging probes with optical imaging offers a useful tool for the study of tumor-induced lymphangiogenesis. LyP-1 may serve as a marker of lymphangiogenesis useful in detecting "high risk" LNs before tumor metastasis and after micro-metastasis, as well as for screening potential anti-lymphatic therapies.

Factors influencing the time of sentinel node visualization in breast cancer patients using intradermal injection of the radiotracer

BACKGROUND

The objective of our study was to determine the important factors that have influence on the time of sentinel node visualization using intradermal injection of (99m)Tc-antimony sulfide colloid.

METHODS

Two hundred fifty consecutive patients with the diagnosis of early-stage breast cancer were evaluated. Anterior and lateral views were acquired in various intervals after intradermal injection of the tracer until 180 minutes or visualization of the sentinel node. The effect of several variables on the time of sentinel node visualization was evaluated by univariate and multivariate analyses.

RESULTS

The time of sentinel node visualization was significantly correlated with age, body mass index (BMI), and interval between biopsy and sentinel node mapping. Standardized beta values for these variables were .1, .3, -.55 respectively.

CONCLUSIONS

Older age and higher BMI can result in slow sentinel node visualization. Longer interval between biopsy and sentinel node mapping can be associated with rapid sentinel node detection.

Current status of sentinel lymph-node biopsy in patients with breast cancer

Axillary node status is the most important prognostic indicator for patients with invasive breast cancer. Sentinel lymph-node biopsy (SLNB) is widely accepted and the preferred procedure for identifying lymph-node metastasis. SLNB allows focused excision and pathological examination of the most likely axillary lymph nodes to receive tumor metastases while avoiding morbidities associated with complete axillary nodal dissection. Since its introduction in the early 1990s, the process of SLNB has undergone continual modification and refinement; however, the procedure varies between institutions and controversies remain. In this review, we examine the technical issues that influence the success of lymph node mapping, discuss the controversies, and summarize the indications and contraindications for axillary node mapping and biopsy in clinical practice.

First demonstration of 3-D lymphatic mapping in breast cancer using freehand SPECT

PURPOSE

Freehand SPECT is a 3-D tomographic imaging modality based on data acquisition with a hand-held detector that is moved freely, in contrast to conventional, fixed gamma camera systems. In this pilot study, the feasibility of freehand SPECT for 3-D lymphatic mapping in breast cancer was evaluated.

METHODS

A total of 85 patients (age: 29-88 years) with an initial diagnosis of invasive breast cancer and no clinical evidence of nodal involvement prospectively underwent sentinel lymph node (SLN) biopsy. Preoperative lymphatic mapping (35-87 MBq (99m)Tc-Nanocoll) included tomographic imaging with a SPECT/CT device (Siemens Symbia T6) serving as reference. Initially, the freehand SPECT approach was assessed in a pilot study consisting of 50 patients. The quality of each freehand SPECT acquisition was assessed and ranked as good, intermediate or poor. In another series comprising a further 35 patients (validation study), a guidance system for the acquisition was implemented based on the results of the pilot study, ensuring acquisitions with good quality. For 3-D tomographic image reconstruction, ad hoc models and iterative reconstruction algorithms were used in all 85 patients. To allow for adequate comparison, SPECT/CT data and freehand SPECT data were registered within the same coordinate system.

RESULTS

In the pilot study, freehand SPECT enabled mapping of 24 of 83 SLNs in 20 of 44 patients (3 dropouts, 3 patients without SLN either in SPECT/CT or in freehand SPECT). Using SPECT/CT as reference, the accuracy of freehand SPECT was 77.8% (7/9 nodes) in scans with good quality, while for intermediate and poor quality scans, the accuracy was reduced to 34.3 and 12.8%, respectively. In the validation study, quality feedback improved the results significantly and freehand SPECT enabled the mapping of at least one SLN in 87.5% of the patients (28/32 - 3 dropouts). Compared to the reference method, freehand SPECT showed a sensitivity of 83.3% (35/42 nodes). False-negative findings were related to insufficient scanning time, insufficient coverage of the axillary region, close proximity of the SLN to the injection site and low tracer uptake in the SLNs.

CONCLUSION

In this preliminary study, we could demonstrate that 3-D localization of SLNs is feasible using freehand SPECT technology. Prerequisites for acquisition of a good scan quality, most likely allowing precise SLN mapping, have been defined. This approach has high potential to allow image-guided biopsy and further standardization of SLN dissection, thus bringing 3-D nuclear imaging into the operating room.

The use of fluorescent dyes and probes in surgical oncology

AIMS AND BACKGROUND

Improved visualization of surgical targets inside of the patient helps to improve radical resection of the tumor while sparing healthy surrounding tissue. In order to achieve an image, optical contrast must be generated by properties intrinsic to the tissue, or require the attachment of special visualization labels to the tumor. In this overview the current status of the clinical use of fluorescent dyes and probes are reviewed.

METHODS

In this review, all experimental and clinical studies concerning fluorescent imaging were included. In addition, in the search for the optimal fluorescent imaging modality, all characteristics of a fluorescent dye were described.

FINDINGS AND CONCLUSIONS

Although the technique of imaging through fluorescence sounds promising and several animal models show efficacy, official approval of these agents for further clinical evaluation, is eagerly awaited.

High-speed dynamic 3D photoacoustic imaging of sentinel lymph node in a murine model using an ultrasound array

Noninvasive photoacoustic sentinel lymph node (SLN) mapping with high spatial resolution has the potential to improve the false negative rate and eliminate the use of radioactive tracers in SLN identification. In addition, the demonstrated high spatial resolution may enable physicians to replace SLN biopsy with fine needle aspiration biopsy, and thus reduce the risk of associated morbidity. The primary goal of this study is to demonstrate the feasibility of high-speed 3D photoacoustic imaging of the uptake and clearance dynamics of Evans blue dye in SLNs. The photoacoustic imaging system was developed with a 30 MHz ultrasound array and a kHz repetition rate laser system. It acquires one 3D photoacoustic image of 166 B-scan frames in 1 s, with axial, lateral, and elevational resolutions of 25, 70, and 200 microm, respectively. With optic-fiber based light delivery, the entire system is compact and is convenient to use. Upon injection of Evans blue, a blue dye currently used in clinical SLN biopsy, SLNs in mice and rats were accurately and noninvasively mapped in vivo using our imaging system. In our experiments, the SLNs were found to be located at approximately 0.65 mm below the skin surface in mice and approximately 1.2 mm in rats. In some cases, lymph vessels and lymphatic valves were also imaged. The dye dynamics--accumulation and clearance--in SLNs were quantitatively monitored by sequential 3D imaging with temporal resolution of as high as approximately 6 s. The demonstrated capability suggests that high-speed 3D photoacoustic imaging should facilitate the understanding of the dynamics of various dyes in SLNs and potentially help identify SLNs with high accuracy.

The location of small tumor deposits in the SLN predicts Non-SLN macrometastases in breast cancer patients

AIMS

The extent to which the location of micrometastases (MIC) or isolated tumor cells (ITC) in sentinel lymph nodes (SLNs) is correlated with the risk of downstream metastases is still unknown. This study examined this issue and compared the impact of MIC/ITC location with other established risk factors.

METHODS

Paraffin slides of SLNs with MIC/ITC-involvement obtained from 68 breast cancer patients were evaluated for MIC/ITC location, lesion size, and various SLN morphologic features. These parameters, together with demographic data and primary tumor characteristics, were analyzed using univariate and multivariate analysis to determine their association with the presence of downstream macrometastases in Non-SLN.

RESULTS

Eighteen of 68 patients with MIC (n=37) or ITC (n=31) had Non-SLN metastases. After multivariate analysis, the location of MIC/ITC in the SLN (parenchyma vs. sinus/vessel) had the strongest association with the presence of Non-SLN macrometastases (p<0.0001), followed by the pT-category (p=0.008). Sixteen of 18 patients with parenchymal involvement but only 2 of 31 without parenchymal involvement had Non-SLN macrometastases. The metric size of the primary tumor and the estrogen receptor status were significantly associated only on univariate analysis (p=0.041, 0.034), whereas the correlation to the size classification for tumor cell deposits (MIC vs. ITC) was not significant (p=0.077).

CONCLUSIONS

The results indicate that lesion location is an important predictor of Non-SLN-macrometastases. This finding may simplify the decision for axillary treatment in patients with small tumor deposits in the SLN.

Sentinel lymph node mapping with type-II quantum dots

Sentinel lymph node (SLN) mapping is an important cancer surgery during which the first lymph node draining the site of a tumor is identified, resected, and analyzed for the presence or absence of malignant cells. Fluorescent semiconductor nanocrystals (quantum dots [QDs]) of the appropriate size, charge, and emission wavelength permit this surgery to be performed rapidly, with high sensitivity and under complete image guidance. We describe the materials and methods necessary for the production and characterization of type-II near-infrared fluorescent QDs, which have been optimized for SLN mapping. They contain a CdTe core, CdSe shell, and a highly anionic, oligomeric phosphine organic coating. We also describe how to utilize such QDs in animal model systems of SLN mapping.

[Sentinel node detection applied to breast cancer: 2007 update]

The technique of detection and resection of the sentinel lymph node applied to early breast cancer management aims to spare the patient with a low risk of lymph node involvement an unnecessary axillary lymphadenectomy. This innovating technique lies on the double hypothesis of an accuracy to predict non sentinel lymph node status and to induce a lower morbidity when compared with axillary lymphadenectomy. This multidisciplinary technique depends on surgeons, nuclear physicians and pathologists. In practice sentinel lymph nodes are detected thanks to two types of tracers, the Blue and the colloids marked with technetium, harvested by the surgeon guided by the blue lymphatic channel and the use of a gamma probe detection, analyzed by the pathologist according to a particular procedure with the concept of serial slices, and possibly immuno histo chemistry. The objectives of this review are to specify the state of knowledge concerning the different steps: detection, surgical resection and the pathological analysis of the sentinels lymph nodes and to focus on validated and controversial indications, and on the main ongoing trials.

Sentinel lymph node biopsy as the new standard of care in the surgical treatment for breast cancer

During the recent years, based on the results of validation studies, the sentinel lymph node biopsy has replaced routine axillary dissection as the new standard of care in early breast cancer. The technique represents a minimally invasive, highly accurate method for axillary staging, which could spare approximately 65-70% of patients unnecessary axillary dissection and its related morbidity. Several technical and clinical controversies have been raised during the development of this new technique; the authors review the most important issues, some questions have already been answered and others are still under debate. As far as the technical aspects are concerned, mapping techniques, appropriate surgical training, options for pathological examination of sentinel lymph nodes and the issue of nonaxillary sentinel lymph nodes are discussed. An update on clinical controversies demonstrates that factors such as large tumor size, palpable axillary nodes, multifocality and multicentricity, previous breast and axillary surgery, and pregnancy are no longer regarded as absolute contraindications for sentinel lymph node biopsy. Feasibility, accuracy and timing of sentinel lymph node biopsy in patients undergoing neoadjuvant chemotherapy remain unsolved issues, as well as the indication of the technique for some subgroups of in situ lesions. Finally, one of the most attractive open forums for debate will be discussed: whether or not completion of axillary dissection in the case of positive SLN is always required.

Impact of Patient- and Disease-Specific Factors on SLNB in Breast Cancer Patients. Are Current Guidelines Justified?

BACKGROUND

The evidence on which to base guidelines for sentinel lymph node biopsy (SLNB) in breast cancer is still limited. In order to facilitate the further implementation of renewed guidelines, we evaluated patient- and disease-specific factors for their impact on the results of SLNB.

MATERIALS AND METHODS

Prospective data acquisition from patients undergoing surgery for primary invasive breast cancer was performed. All patients underwent SLNB using the radiocolloid or the combined technique. The association of patient- and disease-specific factors to detection rate and false-negative rate was calculated using univariate and multivariate analyses (P < 0.05 considered as significant). Calculation of the false-negative rate was based on patients who underwent a backup axillary dissection.

RESULTS

Among 455 consecutively enrolled patients, a significant inverse association to the detection rate was found for extracapsular extension of non-SLN metastases, body mass index (BMI), number of involved lymph nodes, pT category, tumor size, and age. A significant association to the false-negative rate to identify macrometastases was found for pT category, tumor size, and grading. Other factors, such as prior surgery, multicentric tumor growth, or vascular invasion, showed no influence. A cut-point analysis revealed that a tumor size of 2 cm separated the collective of patients with the highest significance in regard to the false-negative rate (9% vs. 25%).

CONCLUSION

Our results indicate that SLNB can be safely used in elderly and obese patients with multicentric tumors and those having undergone prior surgery for benign breast disease. However, the method should be applied with caution in patients with tumors larger than 2 cm.

Image-guided oncologic surgery using invisible light: completed pre-clinical development for sentinel lymph node mapping

BACKGROUND

Invisible near-infrared (NIR) fluorescent light permits high sensitivity, real-time image-guidance during oncologic surgery without changing the look of the surgical field. In this study, we complete pre-clinical development of the technology for sentinel lymph node (SLN) mapping using a large animal model of spontaneous melanoma.

METHODS

Sinclair swine with spontaneous melanoma metastatic to regional lymph nodes were used because of their similarity to human melanoma. Organic lymphatic tracers tested included FDA-approved indocyanine green adsorbed non-covalently to human serum albumin (HSA), and NIR fluorophore CW800 conjugated covalently to HSA (HSA800). The inorganic/organic hybrid tracer tested was type II NIR quantum dots with an anionic coating. Primary tumors received four peri-tumoral injections of each tracer, with a fluorophore dose of 100 pmol to 1 nmol per injection. SLN mapping and image-guided resection were performed in real-time.

RESULTS

Each of the 3 lymphatic tracers was injected into n = 4 separate primary melanomas in a total of 6 animals. All 12 injections resulted in identification of the SLN(s) and their associated lymphatic channels within 1 minute in 100% of cases, despite highly pigmented skin and black fur. Hydrodynamic diameter had a profound impact on tracer behavior in vivo.

CONCLUSIONS

This study completes the pre-clinical development of NIR fluorescence-guided SLN mapping and provides insight into imaging system optimization and tracer choice for future human clinical trials. The technology is likely to eliminate the need for radioactive and colored tracers, permits real-time image guidance throughout the procedure, and assists the pathologist in tissue analysis.

Organic Alternatives to Quantum Dots for Intraoperative Near-Infrared Fluorescent Sentinel Lymph Node Mapping

Intraoperative near-infrared (NIR) fluorescence imaging provides the surgeon with real-time image guidance during cancer and other surgeries. We have previously reported the use of NIR fluorescent quantum dots (QDs) for sentinel lymph node (SLN) mapping. However, because of concerns over potential toxicity, organic alternatives to QDs will be required for initial clinical studies. We describe a family of 800 nm organic heptamethine indocyanine-based contrast agents for SLN mapping spanning a spectrum from 775 Da small molecules to 7 MDa nanocolloids. We provide a detailed characterization of the optical and physical properties of these contrast agents and discuss the advantages and disadvantages of each. We present robust methods for the covalent conjugation, purification, and characterization of proteins with tetra-sulfonated heptamethine indocyanines, including mass spectroscopic site mapping of highly substituted molecules. One contrast agent, NIR fluorescent human serum albumin (HSA800), emerged as the molecule with the best overall performance with respect to entry to lymphatics, flow to the SLN, retention in the SLN, fluorescence yield and reproducibility. This preclinical study, performed on large animals approaching the size of humans, should serve as a foundation for future clinical studies.