Triple-site radiotracer application in breast lymphoscintigraphy and sentinel node discordance

Discordance between peritumoral and subareolar injections for mapping sentinel lymph nodes in the breast

PURPOSE

Sentinel node biopsy (SNB) is a common staging tool for breast cancer. Initially, peritumoral (PT) injections were used, however subareolar (SA) injections were later introduced to simplify the technique. Controversy remains regarding whether PT and SA injections map the same sentinel lymph nodes (SLNs). This study aimed to determine whether the regional location of breast SLNs differs when using PT versus SA injections using a large dataset from a single institution.

METHODS

A total of 1035 patients who underwent breast SNB (PT injections: n = 858 and SA injections: n = 177) with lymphoscintigraphy and SPECT/CT were included. The identified SLN locations using SA injections were compared with those using PT injections. Differences in drainage proportions and odds ratios (ORs) for each clockface breast region and the whole breast were calculated using a two-proportion z-test and Fisher's Exact Test.

RESULTS

A higher proportion of internal mammary SLNs were identified using PT injections for the whole breast (0.30 versus 0.09) and for all breast regions, with all regions showing statistical significance except the upper outer quadrant. Similarly, ORs showed identification of internal mammary SLNs was significantly higher when using PT injections (4.35, 95% CI 2.53 to 7.95). There were no significant differences in identifying axillary SLNs between injection sites.

CONCLUSION

This is the largest cohort study to compare the regional location of breast SLNs identified using PT injections versus SA injections. Discordance was shown in the SLNs identified between injection techniques, with PT injections more frequently identifying internal mammary SLNs.

Update on Sentinel Lymph Node Methods and Pathology in Breast Cancer

Breast cancer stands out as the most commonly diagnosed cancer among women globally. Precise lymph node staging holds critical significance for both predicting outcomes in early-stage disease and formulating effective treatment strategies to control regional disease progression in breast cancer patients. No imaging technique possesses sufficient accuracy to identify lymph node metastases in the early stages (I or II) of primary breast cancer. However, the sentinel node procedure emerges as a valuable approach for identifying metastatic axillary nodes. The sentinel lymph node is the hypothetical first lymph node or group of nodes draining a cancer. In case of established cancerous dissemination, it is postulated that the sentinel lymph nodes are the target organs primarily reached by metastasizing cancer cells from the tumor. The utilization of the sentinel node technique has brought about changes in the assessment of lymph nodes. It involves evaluating the sentinel node during surgery, enabling prompt lymph node dissection when the sentinel node procedure is positive. Additionally, histological ultra-stratification is employed to uncover occult metastases. This review aims to provide an update of this valuable technique, with focus on the practical aspects of the procedure and the different histological protocols of sentinel node evaluation in breast cancer.

Detection of Sentinel Lymph Nodes During Breast Cancer Surgery: A Literature Overview

Introduction. Detecting metastases is an important part of successful breast cancer treatment. Usually, the tumor tissue first spreads to the sentinel lymph nodes. Removal of the latter during surgery and histological examination allows to assess the patient’s di­sease stage, prognosis and treatment. The literature provides more than one approach or a combination of them, allowing us to accurately identify the breast’s sentinel lymph nodes and avoid removing all axillary lymph nodes. Purpose. To review the methods of intraoperative detection of breast sentinel lymph nodes presented in the literature. Research material and methods. Publications were searched using the specialized information search system Google Scholar. Keywords used in the search: breast sentinel lymph nodes, intraoperative detection. After evaluating the exclusion criteria, the review was based on 25 scientific publications. Results. 4 individual measures and 2 combinations of them can be used to detect sentinel breast lymph nodes during surgery. The materials used can be injected in 6 different ways. Conclusions. The combination of technetium-99m radiocolloid and methylene blue can be evaluated as the best method for intraoperative detection of sentinel lymph nodes in breast cancer patients. On the other hand, due to radiation and operating costs, more attention is being paid to the use of indocyanine green, superparamagnetic iron oxide, methylene blue dye, and the detection of metastases without surgery. Superficial methods of injecting the substance should be combined with deep ones due to the possibility of detecting extra-axillary sentinel lymph nodes of the breast. Ultimately, all decisions must be made on a case-by-case basis.

Sentinel Lymph Node Methods in Breast Cancer

Breast cancer is the most frequent cancer diagnosed in women worldwide. Accurate lymph node staging is essential for both prognosis (of early-stage disease) and treatment (for regional control of disease) in patients with breast cancer. The sentinel lymph nodes are the regional nodes that directly drain lymph from the primary tumor. No imaging modality is accurate enough to detect lymph node metastases when a primary breast cancer is at an early stage (I or II), but sentinel lymph node biopsy is a highly reliable method for screening axillary nodes and for identifying metastatic (including micro-metastatic) disease in regional lymph nodes. Despite the widespread use of sentinel lymph node biopsy for early-stage breast cancer, relevant variations have been described regarding practical aspects of the procedure, and some variability has initially been reported regarding the rates of intraoperative sentinel lymph node identification and of false-negative findings, most likely because of differences in the size of the populations being investigated and in lymphatic mapping techniques. Nevertheless, using adequate learning curves and once a multidisciplinary team is experienced with the procedure, improved levels of accuracy are achieved.

Techniques for sentinel node biopsy in breast cancer

INTRODUCTION

Sentinel node biopsy (SNB) is the standard of care in women with breast cancer (BC) and clinically non suspicious axillary lymph nodes (LNs), due to its high negative predictive value (NPV) in the assessment of nodal status. SNB has significantly reduced complications related to the axillary lymph node dissection, such as lymphedema and upper limb dysfunction.

EVIDENCE ACQUISITION

The gold standard technique for SNB is the blue dye (BD) and technetium labelled nanocolloid (Tc-99m) double technique. However, nuclear medicine is not available in all Institutions and several new tracers and devices have been proposed, such as indocyanine green (ICG) and superparamagnetic iron oxides (SPIO). All these techniques show an accuracy and detection rate not inferior to that of the standard technique, with different specific pros and cons. The choice of how to perform a SNB primarily depends on the surgeon's confidence with the procedure, the availability of nuclear medicine and the economic resources of the Institutions. In this setting, new tracers, hybrid tracers and imaging techniques are being evaluated in order to improve the detection rate of sentinel lymph nodes (SNs) and minimize the number of unnecessary axillary surgeries through an accurate preoperative assessment of nodal status and to guide new minimally invasive diagnostic procedures of SNs. In particular, the contrast-enhanced ultrasound (CEUS) is an active field of research but cannot be recommended for clinical use at this time.

EVIDENCE SYNTHESIS

The ICG fluorescence technique was superior in terms of DR, as well as having the lowest FNR. The DR descending order was SPIO, Tc, dual modality (Tc/BD), CEUS and BD.

CONCLUSIONS

This paper is a narrative review of the most common SNB techniques in BC with a focus on recent innovations.

Risk factors for nonvisualization of the sentinel lymph node on lymphoscintigraphy in breast cancer patients

Background

Accurate sentinel lymph node (SLN) staging is essential for both prognosis and treatment in patients with breast cancer. However, the preoperative lymphoscintigraphy may fail to visualize the SLN in some patients. The purpose of this retrospective study was to identify risk factors associated with SLN nonvisualization on lymphoscintigraphy. For this single-center retrospective study, all data of lymphoscintigraphy of SLN procedures from March 2011 to April 2021 were collected and reviewed from the Amsterdam UMC database.

Results

A total of 1886 SLN procedures were included in this study. The SLN nonvisualization rate was 25.1% on lymphoscintigraphy at 4 h post-injection. The SLN nonvisualization rate decreased to 9.4% after reinjection. Multivariable analysis showed that age ≥ 70 years (P < 0.001; OR: 2.27; 95% CI: 1.46–3.53), BMI ≥ 30 kg/m² (P = 0.031; OR: 1.48; 95% CI: 1.04–2.12) and nonpalpable tumors (P = 0.004; OR: 1.54; 95% CI: 1.15–2.07) were independent predictors of SLN nonvisualization. Tumor location, brand of radiopharmaceutical, injected dose and volume, experience of preparer and administrator were not associated with SLN nonvisualization. None of the patient, tumor or tracer characteristics were associated with SLN nonvisualization after radiotracer reinjection.

Conclusions

This study shows that risk factors for SLN nonvisualization in breast cancer patients during preoperative lymphoscintigraphy are age ≥ 70 years, BMI ≥ 30 kg/m² and nonpalpable tumors. Our results support the notion that SLN lymphoscintigraphy is a very robust technique that does not depend on the experience of the preparer or administrator of the radiotracer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00793-8.