Sentinel lymph node biopsy in breast cancer: an overview of the Japanese experience

Moving a neodymium magnet promotes the migration of a magnetic tracer and increases the monitoring counts on the skin surface of sentinel lymph nodes in breast cancer

Background

We suspected that moving a small neodymium magnet would promote migration of the magnetic tracer to the sentinel lymph node (SLN). Higher monitoring counts on the skin surface before making an incision help us detect SLNs easily and successfully. The present study evaluated the enhancement of the monitoring count on the skin surface in SLN detection based on the magnet movement in a sentinel lymph node biopsy (SNB) using superparamagnetic iron oxide (SPIO) nanoparticles.

Methods

After induction of general anesthesia, superparamagnetic iron oxide nanoparticles were injected sub-dermally into the subareolar area or peritumorally. The neodymium magnet was moved over the skin from the injection site to the axilla to promote migration of the magnetic tracer without massage. A total of 62 patients were enrolled from February 2018 to November 2018: 13 cases were subjected to magnet movement 20 times (Group A), 8 were subjected to 1-min magnet movement (Group B), 26 were given a short (about 5 min) interval from injection to 1-min magnet movement (Group C), and 15 were given a long (about 25 min) interval before 1-min magnet movement using the magnetometer’s head (Group D). In all cases, an SNB was conducted using both the radioisotope (RI) and SPIO methods. The monitoring counts on the skin surface were measured by a handheld magnetometer and compared among the four groups. Changes in the monitoring count by the interval and magnet movement were evaluated.

Results

The identification rates of the SPIO and RI methods were 100 and 95.2%, respectively. The mean monitoring counts of Group A, B, C, and D were 2.39 μT, 2.73 μT, 3.15 μT, and 3.92 μT, respectively (p < 0.0001; Kruskal-Wallis test). The monitoring counts were higher with longer magnet movement and with the insertion of an interval. Although there were no relationships between the monitoring count on the skin surface and clinicopathologic factors, magnet movement strongly influenced the monitoring count on the skin surface.

Conclusion

Moving a small neodymium magnet is effective for promoting migration of a magnetic tracer and increasing monitoring counts on the skin surface.

Trial registration

UMIN, UMIN000029475. Registered 9 October 2017

Successful Internal Mammary Visualization With Periareolar Injections of Tc-99m Antimony Sulfur Colloid in Sentinel Node Breast Lymphoscintigraphy

PURPOSE

The subareolar and periareolar injection techniques result in higher detection rates and do not require tumor localization in impalpable lesions when compared with the peritumoral technique. One of the main criticisms, however, is the widely reported inability to detect internal mammary nodes. This contrasts with our clinical experience using Tc-99m antimony sulfur colloid, in which internal mammary nodes are commonly seen.

METHODS

A retrospective analysis of 241 patients over 38 months was performed to investigate the ability of our periareolar injection technique to detect internal mammary lymph node drainage in breast cancer sentinel node lymphoscintigraphy. Four injections of 5 to 10 MBq (0.14-0.27 mCi) Tc-99m antimony sulfur colloid were administered on the day of surgery followed by massage and imaging. The radioisotope was suspended in 0.1 mL with a 0.5-mL air lock. Each injection was performed over 2 seconds with a 25-gauge needle at a depth of 1.1 to 1.3 cm. Patients whose records could not be retrieved or who underwent an injection technique apart from periareolar or peritumoral were removed from the analysis.

RESULTS

One hundred thirty-three patients underwent the periareolar technique, 72 patients underwent the peritumoral technique, and 36 patients were excluded from the analysis. Internal mammary drainage was seen in 24 of 133 (18.0%) patients, of which 12 (9%) were seen only in the internal mammary chain. This is much higher than previous studies quoting 0.0% to 4.3% and is similar to previously reported rates using the peritumoral technique.

CONCLUSIONS

Our periareolar injection technique using Tc-99m antimony sulfur colloid is able to detect internal mammary lymph nodes in at least 18.0% of patients.

Added value of the presence of blue nodes or hot nodes in sentinel lymph node biopsy of breast cancer

BACKGROUND

Combined use of blue dye and radiocolloid is considered to be useful for sentinel lymph node (SLN) biopsy of breast cancer. Whether both techniques together is superior to either alone was analyzed.

PATIENTS AND METHODS

A consecutive series of 308 cases of breast cancer who underwent SLN biopsy using the combination technique was used. The frequency of a blue node or hot node was analyzed in all cases and only node-positive cases. Furthermore, the frequency of a blue node and hot node together, or either alone, and the highest radiocount of the SLNs in each case were examined for correlation with 8 clinicopathologic features. Three types of SLN containing both blue dye and radioactivity (blue-hot node), blue dye alone (blue-only node) and radioactivity alone (hot-only node), and the SLN radiocounts were analyzed for correlation with metastatic tumor.

RESULTS

Of 308 cases, a blue node was present in 298 (97%), a hot node in 295 (96%), and either a blue or hot node in 306 (99%). The presence of a blue node or hot node was similarly affected by previous surgical biopsy and body mass index (BMI), and the presence of a hot node was also affected by age and tumor location. However, the presence of either a blue node or hot node was not affected by any of these characteristics. Of 77 node-positive cases, 8 (10%), 15 (19%) and 6 (8%) were considered to be node-negative based on blue node, hot node and either blue node or hot node positivity, respectively. The frequency of positivity for SLN metastasis decreased in order from blue-hot, blue-only to hot-only nodes. Of 62 cases with metastatic hot nodes, six (10%) were negative when the hottest node was examined, but the second-hottest node was positive.

CONCLUSIONS

The added value of the presence of blue node or hot node was confirmed in the SLN biopsy using the combination technique, which suggests that all blue nodes and hot nodes need to be harvested.

99mTc-phytate is better than 99mTc-human serum albumin as a radioactive tracer for sentinel lymph node biopsy in breast cancer

PURPOSE

Several radioactive agents are used for sentinel lymph node biopsy (SLNB) in breast cancer, but we are still unsure which of these is best. We retrospectively compared the effectiveness of two radioactive agents, 99mTc-phytate and 99mTc-human serum albumin (HSA), when used in combination with blue dye.

METHODS

A consecutive series of 533 clinically node-negative patients with a collective 539 breast carcinomas were divided into two groups for treatment with SLNB. The HSA-group consisted of 264 patients (with a collective 266 breast cancers) and the P-group consisted of 269 patients (with a collective 273 breast cancers) treated with 99mTc-HSA and 99mTc-phytate, respectively, in combination with blue dye. We analyzed the identification and radioactivity of SLNs in the two groups.

RESULTS

The identification rate of SLN was significantly higher in the P-group than in the HSA-group. The same results were produced by analysis using the radioactive agent alone, but not by using the blue dye alone. Most importantly, the highest radioactivity of SLNs per case was more than five times higher in the P-group than in the HSA-group, and this difference was significant.

CONCLUSION

Our historical analysis of the two radioactive agents used in different periods could not exclude the influence of the improved skill of the surgeons. However, because the specific accumulation of phytate in SLNs was greater than that of HSA, phytate might result in a higher SLN identification rate. Thus, 99mTc-phytate is better than 99mTc-HSA as a radioactive agent for SLNB in breast cancer.

Fluorescence navigation with indocyanine green for detecting sentinel lymph nodes in breast cancer

BACKGROUND

Sentinel lymph node biopsy using a vital dye is a convenient and safe method to assess lymph node status in breast cancer. However, intensive training is necessary to obtain a satisfactory detection rate and to avoid false-negative results. This paper presents a novel method using indocyanine green fluorescence imaging to detect sentinel lymph nodes.

METHODS

Fluorescence images were obtained using a charge coupled device camera with a cut filter as the detector, and light emitting diodes at 760 nm as the light source. When indocyanine green was injected around the areola, subcutaneous lymphatic channels draining from the areola to the axilla were visible by fluorescence within a few minutes. The sentinel lymph node was then dissected by fluorescence navigation.

RESULTS

Sentinel lymph node biopsy using the present method was performed on eighteen patients. Subcutaneous lymphatics were detectable by fluorescence in all patients, and sentinel nodes were successfully identified in 17 of 18 cases (detection rate:94%). It was possible to detect the lymphatic channels and nodes receiving indocyanine green with higher sensitivity by the fluorescence signal than by the green color.

CONCLUSION

Sentinel node biopsy guided by indocyanine green fluorescence imaging is a promising technique for further clinical exploration.

Surgical pathological staging of breast cancer by sentinel lymph node biopsy with special emphasis on the histological work-up of axillary sentinel lymph nodes

Axillary nodal status assessed by traditional histological methods is a proven independent prognostic factor in breast cancer. Sentinel lymph node biopsy is a surgical pathologic staging procedure that not only allows the selective removal of the most likely sites of lymphogenic metastases, but also enables upstaging of breast carcinoma by detecting nodal involvement undetected by standard methods of nodal staging. This review highlights the upstaging potential of sentinel node biopsy. It also suggests that incomplete reporting of the pathological methods may make the comparisons of results from different studies difficult. The article also describes a few methods that have been claimed optimal but are probably not, and it formulates basic considerations for building up a histological protocol that can identify all metastases larger than 2 mm, which are of unquestionable prognostic relevance. These considerations are also useful for the detection of micrometastases. Issues of pathological reporting of sentinel nodal findings are also highlighted, with emphasis on the lack of standardization and on the differentiation of isolated tumor cells from micrometastases. Finally the stepwise building up of our current histology protocol and our experience gained since the introduction of sentinel node biopsy in 1997 is also briefly summarized.

Sentinel Lymph Node Biopsy or Detection of Micrometastasis in Bone Marrow: Which Might Be an Alternative to Axillary Lymph Node Dissection in Breast Cancer Patients?

Axillary lymph node status has limited prognostic significance in breast cancer patients and much improvement can be made. Sentinel lymph node biopsy is emerging as an alternative to axillary lymph node dissection for staging, but its prognostic relevance is still uncertain. Detection of micrometastases in sentinel nodes and bone marrow may provide more information, but the clinical significance still needs to be confirmed by ongoing large trials. In this review, we focus on the possibility of sentinel lymph node biopsy or detection of bone marrow micrometastasis replacing traditional axillary lymph node dissection.

Optimal particle size of radiocolloid for sentinel node identification in breast cancer — Electron microscopic study and clinical comparison

BACKGROUND

Sentinel node (SN) biopsy using a radiotracer is easy to learn, reproducible, and performed by the majority of breast cancer surgeons. However, this technique raises the question: what is the optimal particle size of colloid?

METHODS

Patients were injected with conventional tin colloid (median particle diameter: 700 nm) and the predominant particle size of radiocolloid retained in the SN was measured using electron microscopy. This showed a narrow distribution of colloidal size (100-150 nm). Patients were then injected with modified tin colloid having a median particle size of 100 nm. A clinical comparison was performed between conventional particle size or reduced particle size tin colloid and the SN biopsy success rate, the number of SNs, and the colloidal uptake in SNs.

RESULTS

A total of 118 patients were injected with the conventional tin colloid (group I) and 124 patients with the smaller particle colloid (group II). The identification rate and the number of SN in both groups were almost equal, and the patients with low-uptake SNs were not significantly less in group I(p = 0.55). However, in the subgroup of patients 60 years of age or more, group II had significantly more SNs than group I(1.4 vs 1.9; p = 0.03) and low-uptake SNs were significantly less common than in group I(p = 0.02).

CONCLUSIONS

The improvement of colloidal uptake in SNs using the smaller particle size tin colloid was confirmed, and this impact was statistically significant in the older population.

Current Controversies Concerning Sentinel Lymph Node Biopsy for Breast Cancer

BACKGROUND AND METHODS

The objectives of this article are to review existing controversies regarding sentinel lymph node (SLN) biopsy and to identify potential areas of consensus in order to eliminate routine axillary lymph node dissection (ALND).

RESULTS

A combination of peritumoral injection with radioisotopes and subdermal or subareolar injection with blue dye may result in enhanced success rates of SLN identification. Preoperative lymphoscintigraphy is most useful for detecting an internal mammary SLN, but the practicability of internal mammary SLN biopsy is still in the investigative stage. Intraoperative diagnosis of SLN is useful because patients with SLN metastases may be treated immediately with ALND, but it is unreasonable to expect that either examination of frozen sections or imprint cytology will detect every metastatic disease. SLN micrometastases may be of prognostic importance and these can be identified with H and E staining on permanent sections of 200 micro m intervals. While ALND is preferable for patients even with a small tumor (T1) and SLN micrometastases, radiation therapy is an acceptable alternative. SLN biopsy may be indicated for patients with DCIS detected as a palpable mass or those with large calcification areas in the breast. The accuracy of SLN biopsy after neoadjuvant chemotherapy is considered to be unproven.

CONCLUSION

Since SLN biopsy has been adopted by surgeons around the world, consistency of technique and case selection has attained great significance.

Is it necessary to perform prospective randomized studies before sentinel node biopsy can replace routine axillary dissection?

BACKGROUND AND METHODS

Sentinel lymph node (SLN) biopsy is a useful way of assessing axillary nodal status in breast cancer patients. Recently, several surgeons have begun to abandon routine axillary dissection on the basis of negative SLN biopsy results. However, there is no long-term data comparing outcomes of SLN biopsy alone with those of axillary dissection. This paper reviews and discusses the significance of ongoing prospective randomized clinical trials aiming at the elimination of axillary dissection.

RESULTS

SLN biopsy is known to have a false-negative rate. It can thus be assumed that SLN biopsy alone may fail to remove the disease completely from the axilla in some patients. As a result, it is not known whether SLN biopsy alone will increase the axillary recurrence rate, particularly in patients with a high risk of axillary lymph node metastasis. Recently, moreover, locoregional control appears to be important for enhancing survival in conjunction with adjuvant systemic therapy. It is therefore still unclear to what extent the benefits of SLN biopsy outweigh the risks and, if so, for which patient groups.

CONCLUSION

Before SLN biopsy can replace routine axillary dissection, research using long-term regional controls and investigation of survival in a prospective randomized trial are essential. Except for clinical research studies, routine axillary dissection should not be abandoned until and unless there is documentation of extensive experience and a low false negative rate. Even with such evidence, however, patients undergoing SLN biopsy without concomitant axillary dissection should be informed of the risk of a false-negative result.

Sentinel lymph node biopsy without axillary dissection after an intraoperative negative histological investigation in 358 invasive breast cancer cases

BACKGROUND

Sentinel lymph node biopsy (SLNB) is an important treatment option for breast cancer patients, as it can accurately predict axillary status. Our previous study using dye with or without radioisotope showed the accuracy and sensitivity of SLNB to be 97% and 94%, respectively. Based on these results, axillary lymph node dissection (ALND) was eliminated starting in January, 1999 in patients with intraoperatively negative SLNB at our institution. The present study shows the results and outcomes of SLNB as a sole procedure for patients with invasive breast cancer.

PATIENTS AND METHODS

Three-hundred-fifty-four patients and 358 cases of invasive breast cancer (4 bilateral breast carcinoma) treated with SLNB alone after an intraoperative negative SLNB were studied prospectively from January 1999 to December 2001.

RESULTS

The number of the identified SLNs per case ranged from 1 to 8 (mean, 2.5). Of a total of 358 cases, 297 (83%) were treated with hormone therapy and/or chemotherapy, and 281 (78%) were treated with radiotherapy to the conserved breast (50 Gy+/-10 Gy boost), the axilla (50 Gy), or the both sites. After a median follow-up of 21 (range 6-42) months, no patient developed an axillary relapse. Four cases initially recurred in distant organs and one case in the conserved breast.

CONCLUSIONS

Our results indicate that an intraoperative negative SLNB without further ALND may be a safe procedure when strict SLNB is performed. To better assess the safety, however, may require longer follow-up.

Relevance and practicability of internal mammary sentinel node biopsy for breast cancer

OBJECTIVES AND METHOD

Recent observations in breast cancer patients undergoing sentinel lymph node (SLN) mapping, in which drainage can be traced to the internal mammary node (IMN) chain, have renewed interest in the staging and treatment of the disease. This paper discusses the relevance of internal mammary SLN biopsy and suggests an optimal procedure for the identification of the SLN in the IMN chain.

RESULTS

Axillary lymph node (AX) and IMN status have similar predictive relevance for survival, while the involvement of IMNs has prognostic value for AX-negative as well as AX-positive patients. Although parasternal recurrence is fortunately rare after modified radical mastectomy or breast conserving surgery, if left untreated it not infrequently develops as clinically evident disease in patients with histologic involvement of IMNs. "Hot" internal mammary SLNs can be identified by means of lymphoscintigraphy and gamma-detection probe after peritumoral injection of radioisotopes. A positive internal mammary SLN biopsy would be an indication for internal mammary radiotherapy as well as adjuvant systemic treatment. However, the reported incidence of positive internal mammary SLNs is still lower than expected because the spread of radioactivity does not necessarily coincide with nodal involvement.

CONCLUSION

Internal mammary SLN biopsy has proven to be relevant but not yet fully practical because more data are needed on the collection of a "Hot" internal mammary SLN and on pathologic involvement. This means that internal mammary SLN biopsy should be regarded as still investigative.

Therapeutic relevance of breast cancer micrometastases in sentinel lymph nodes

BACKGROUND AND METHODS

This review examines the various methods of detecting occult breast cancer metastasis in the sentinel lymph node (SLN). The prognostic relevance of such micrometastases and isolated tumour cells, and their impact on stage migration and decision making with respect to axillary dissection and adjuvant systemic therapy, are discussed.

RESULTS

Examination of SLNs by serial section with haematoxylin and eosin and/or immuno histochemical staining significantly increases the detection rate of micrometastases, even in patients with very small (T1) tumours. However, the prognostic relevance of isolated tumour cells and small micrometastases is uncertain. Moreover, deciding which patients might benefit from axillary dissection is complicated by the fact that adjuvant radiotherapy and systemic chemotherapy alone may eradicate most micrometastases.

CONCLUSION

Ongoing randomized trials comparing the results of SLN biopsy alone with those of axillary dissection should answer the question of whether isolated tumour cells and small micrometastases are clinically relevant. This should also indicate which patients with SLN micrometastasis are likely to benefit from axillary dissection. In this sense, SLN biopsy must be considered still to be at an investigative stage; outwith clinical trials complete axillary dissection should be performed on all patients with SLN micrometastasis.

Predictive and prognostic markers for invasive breast cancer

Breast cancer is one of the most serious carcinomas among women worldwide, yet there are now encouraging signs that improvements in the mortality rate may be possible. The use of hormone therapy and chemotherapy has been widely accepted as treatment for breast cancer. Predictive factors can be used to predict response or lack of response to a particular therapy, and prognostic factors can be useful in making decisions about which patients should receive adjuvant therapy. Histopathology remains the universal basis of diagnosis, with the identification of new surrogate markers for potential new treatments. These are aimed at blocking tumor cell proliferation, neutralizing growth factors, stimulating apoptosis and blocking metastasis, and represent an integral part of new approaches for improving clinical management of patients with breast cancer. We review the standard predictive and prognostic factors that are routinely available today, and also describe some of the new, potential markers that are currently under investigation.