The Reproducibility in Routine Clinical Practice of Sentinel Lymph Node Identification by Pre-operative Lymphoscintigraphy in Patients with Cutaneous Melanoma

Next generation of radiotracers for sentinel lymph node biopsy: What is still necessary to establish new imaging paradigms?

Sentinel lymph node (SLN) biopsy is now the standard of care for regional staging in several solid tumors. The interstitial administration of a radiotracer around the primary tumor provide the possibility to sequentially obtain images with a gamma camera and visualize lymphatic mapping and the SLN. There is, however, a large geographical variability in those radiotracers and nanocolloids ranging from 15-100nm which are most widely employed in Europe, while filtered and unfiltered ^99mTc-sulfur colloid (range 20-1000nm) is usually used in the USA with different drawbacks in its use. The new radiotracer ^99mTc-Tilmanocept, designed specifically for the identification of SLNs and recently becoming commercially available in USA and Europe, appears to have the potency to overcome the shortcomings described for the conventional radiotracers used until now for SLN biopsy and at the same time to transform current imaging paradigms. After delineating the challenges for the next generation of radiotracers, this paper discusses the properties of ^99mTc-Tilmanocept, its validation process for SLN biopsy and its emerging clinical applications in various malignancies.

Reproducibility of lymphoscintigraphic evaluation of the upper limb

BACKGROUND

Although reproducibility studies are missing, a lymphoscintigraphic evaluation of the upper limb is often used in routine practice to diagnose lymphedema and in clinical research, for example, to investigate the effect of a physical treatment. Therefore, the aim of the present study was to investigate the reproducibility of the lymphoscintigraphic evaluation of the upper limb.

METHODS AND RESULTS

In breast cancer patients, 20 lymphoscintigraphic evaluations of the upper limb were performed on two test occasions with an interval of 1 week. (99m)Tc nanocol was injected subcutaneously in the hand. A standardized protocol was applied. In the early phase, two static images of the injection places were taken and in between dynamic images of both axilla during 40 min (15 min rest, 15 min squeezing a ball, and 15 min rest). After a break of 70 min, a static image of the injection places and of the axilla was made. At the end, a partial whole body image was acquired. A strong reproducibility was found for the following quantitative variables (ICC 0.75 to 0.85): change of uptake in axilla during the break; change of extraction from hands during the break; and extraction and uptake in the late phase. The other quantitative variables (i.e., extraction form the hands in the early phase, time of arrival, accumulation rate, and uptake in axilla in the early phase) had weak to moderatie reproducibility (ICC 0.07 to 0.70). All qualitative variables (i.e., number of lymph nodes in the axilla, upper arm and elbow/lower arm, gradation of lymph collectors in upper or lower arm and of dermal backflow, and presence of lymph collaterals) had strong to very strong reproducibility (ICC 0.76 to 1.00).

CONCLUSION

A lymphoscintigraphy of the upper limb is a reproducible imaging tool to assess lymph transport quantitatively and qualitatively.

Sentinel lymph node mapping in melanoma: the issue of false-negative findings

Management of cutaneous melanoma has changed after introduction in the clinical routine of sentinel lymph node biopsy (SLNB) for nodal staging. By defining the nodal basin status, SLNB provides a powerful prognostic information. Nevertheless, some debate still surrounds the accuracy of this procedure in terms of false-negative rate. Several large-scale studies have reported a relatively high false-negative rate (5.6%-21%), correctly defined as the proportion of false-negative results with respect to the total number of "actual" positive lymph nodes. In this review, we identified all the technical aspects that the nuclear medicine physician, the surgeon, and the pathologist should take into account to improve accuracy of the procedure and minimize the false-negative rate. In particular, SPECT/CT imaging detects more SLNs than those found by planar lymphoscintigraphy. Furthermore, the nuclear medicine community should reach a consensus on the radioactive counting rate threshold to better guide the surgeon in identifying the lymph nodes with the highest likelihood of housing metastases ("true biologic SLNs"). Analysis of the harvested SLNs by conventional techniques is also a further potential source for error. More accurate SLN analysis (eg, molecular analysis by reverse transcriptase-polymerase chain reaction) and more extensive SLN sampling identify more positive nodes, thus reducing the false-negative rate.The clinical factors identifying patients at higher-risk local recurrence after a negative SLNB include older age at diagnosis, deeper lesions, histological ulceration, and head-neck anatomic location of the primary lesion.The clinical impact of a false-negative SLNB on the prognosis of melanoma patients remains controversial, because the majority of studies have failed to demonstrate overall statistically significant disadvantage in melanoma-specific survival for false-negative SLNB patients compared with true-positive SLNB patients.When new more effective drugs will be available in the adjuvant setting for stage III melanoma patients, the implication of an accurate staging procedure for the sentinel lymph nodes will be crucial for both patients and clinicians. Standardization and accuracy of SLN identification, removal, and analysis are required.

Lymphoscintigraphy in clinical routine practice: reproducibility and accuracy in melanoma patients with a long-term follow-up

INTRODUCTION

The sentinel node status is the most important single factor determining overall survival for patients with localized melanoma. Preoperative lymphoscintigraphy (LS) is essential in locating the correct sentinel lymph node (SN) and the reproducibility of the method determines the accuracy of the sentinel node biopsy (SNB). This study aims at determining the reproducibility and accuracy of LS in routine clinical practice after long-term follow-up.

PATIENTS AND METHODS

One hundred and eight melanoma patients with clinically unpredictable lymphatic drainage were prospectively enrolled to undergo two LS. The first LS was performed to determine the site and number of the lymphatic basins to plan SNB anesthesia and the second preoperative LS was to allow SN localization intra-operatively.

RESULTS

Lymphatic drainage was demonstrated in all patients. In 84 of 108 cases, both LSs were concordant in terms of site and number of nodal basins visualized. After a median follow-up of 80 months, no nodal recurrence was observed in the five patients with a decreased number of lymph node basins. In the group with increased number of lymph node basins, one patient developed nodal metastases in the same regional lymph node basin visualized by both LS studies.

CONCLUSION

LS is an accurate and reproducible method to determine the localization of the sentinel node in the day-to-day routine to clinical practice when primary melanoma is also located in body sites with variable lymphatic drainage.

Evaluation of incomplete sentinel node biopsy procedures and sentinel node positivity rates as surgical quality-assurance parameters in melanoma patients

BACKGROUND

There is little literature describing quality assurance (QA) validation of an individual surgeon's ability to perform sentinel node biopsy (SNB) in melanoma patients. This study aims to evaluate incomplete SNB rates and SNB positivity rates as potential QA parameters.

METHODS

An institutional database identified 2,874 patients with primary melanoma who had SNB performed when there was lymphoscintigraphy drainage to a single lymphatic field. Lymphoscintigraphy data were obtained from another database. Lymphoscintigraphy utilized small-particle colloid, allowing visualization of channels entering sentinel nodes on early dynamic scanning. Incomplete SNB was defined as retrieval of fewer sentinel nodes than identified on lymphoscintigraphy.

RESULTS

The overall rate of incomplete SNB was 17.7 % (including axilla 7.8 %, neck 23.3 %, and groin 28.8 %). Individual surgeons varied significantly in their proportion of SNBs performed in each region (p < 0.001). The surgeons' overall incomplete SNB rate varied significantly (p < 0.001). The surgeons' incomplete SNB rate in the axilla ranged 3-16 % (p < 0.001), median 6 %; groin 21-41 % (p = 0.002), median 26 %; and neck 19-43 % (p = 0.374), median 22 %. The respective axillary, groin, and neck SNB positivity rate for incomplete SNB patients were 10, 23, and 18 % compared to "complete" SNB patients 14, 19, and 14 %. There were no significant differences between surgeons' SNB positivity rates.

CONCLUSIONS

Incomplete SNB rates vary between surgeons in each region. SNB positivity rates do not vary commensurate with the incomplete SNB rates. The ranges described could be used as QA parameters, however because none of these experienced surgeons are outliers, the robustness of these parameters remains unproven.

Incomplete sentinel node biopsy is not clearly related to survival or regional recurrence in cutaneous melanoma patients

BACKGROUND

In melanoma patients, we define incomplete sentinel node biopsy (I-SNB) as when fewer lymph nodes are removed during sentinel node biopsy (SNB) than identified on preoperative lymphoscintigraphy (LS). This study quantifies the frequency of I-SNB and evaluates any correlation with patient outcomes.

METHODS

Evaluation of a prospective database of consecutive patients having LS and negative SNB from 1996 to 2006. Additional LS information was obtained from a nuclear medicine database. All statistical analyses were performed using the IBM SPSS Statistic 19.0 software package.

RESULTS

I-SNB occurred in 20% of the cohort (n = 2007). For axillary (n = 895), groin (n = 569), and neck/axial patients (n = 334) I-SNB occurred in 12%, 26%, and 28% of cases, respectively (P < .001). On univariate analysis, there was a significant association between I-SNB and worse disease-free survival (DFS), P = .007 and trend toward worse melanoma-specific survival (MSS), P = .056. I-SNB was not associated with worse regional recurrence-free survival (RRFS), P = .144. There was no relationship between I-SNB and worse DFS, RRFS, or MSS on multivariate analysis. Sentinel node region (axilla better than groin and neck/axial) had a significant association with RRFS (P = .039) on univariate analysis and DFS on univariate (P = .009) and multivariate analysis. Significantly worse outcomes for MSS, DFS, and RRFS were seen with male gender, increasing age, high mitotic count, ulceration, and increasing Breslow thickness.

CONCLUSION

This study demonstrates no statistically significant relationship between I-SNB and patient outcomes when adjusting for known prognostic factors. These data do not exclude the possibility that I-SNB may have a weak association with worse outcomes.

Sentinel lymph node biopsy in melanoma patients

Appropriate surgical management of regional lymph nodes is critical in patients with cutaneous melanoma. The use of intraoperative lymphatic mapping and sentinel lymph node biopsy (SLNB) has increased significantly in the past decade. SLNB is performed as minimally invasive procedure that provides accurate staging of melanoma patients with no clinically detectable nodal disease. In many melanoma units across the world, it became the standard for detection of occult regional node metastasis in patients with intermediate-thickness primary melanoma. Use of SLNB in patients with thin melanomas is still under evaluation. Although SLNB has been established as staging procedure in melanoma patients, its therapeutic role is still not clear. Large-scale ongoing randomized trials should elucidate whether SLNB with complete lymphadenectomy has a survival benefit in melanoma patients with early lymph node metastases compared to 'watch-and-wait' policy (observation).

Breast cancer during pregnancy

Breast cancer in pregnancy is an uncommon situation but poses dilemmas for patients and their physicians. There is a paucity of prospective studies regarding diagnosis and treatment of breast cancer during pregnancy. Women diagnosed with breast cancer during pregnancy have similar disease characteristics to age-matched controls. Current evidence suggests that diagnosis may be carried out with limitations regarding staging. Surgical treatment may be performed as for non-pregnant women. Radiotherapy and endocrine or antibody treatment should be postponed until after delivery. Chemotherapy is allowed after the first trimester. Physicians should be aggressive in the workup of breast symptoms in the pregnant population to expedite diagnosis and allow multidisciplinary treatment without delay.

Lymphatic drainage pathways of the breast and the upper limb

OBJECTIVE

To determine how often the sentinel lymph node (SLN) draining the breast is the same node as the SLN draining the upper limb. A common SLN might increase the risk of upper limb breast cancer-related lymphoedema after SLN biopsy.

METHODS

Patients with invasive breast cancer, identified as being suitable for axillary lymph node dissection, were injected preoperatively with 40 MBq of technetium-99m (Tc)-human polyclonal immunoglobulin G intradermally into the ipsilateral breast and 3 MBq of indium-111 (In)-human polyclonal immunoglobulin G intradermally into the ipsilateral hand, or vice versa. Axillary lymph nodes were removed, separated and assayed in a well counter for Tc and In.

RESULTS

Fifteen patients entered the study. In 13 of 15 patients, the 'hottest' lymph node for Tc was separate from the 'hottest' lymph node for In. In two of 15 patients the 'hottest' lymph node for Tc was also the 'hottest' lymph node for In, suggesting a common drainage pathway from the ipsilateral breast and upper limb.

CONCLUSION

Although the majority of patients has different pathways of lymphatic drainage from the ipsilateral breast and upper limb, in a small minority of patients the drainage pathway is through a common SLN. Such patients may be at increased risk of developing upper limb breast cancer-related lymphoedema after SLN biopsy.

Three-dimensional visualisation of lymphatic drainage patterns in patients with cutaneous melanoma

BACKGROUND

Lymphoscintigraphy accurately maps lymphatic drainage from sites of cutaneous melanoma to the draining sentinel lymph nodes. The Sydney Melanoma Unit has accumulated lymphoscintigraphy data from over 5000 patients with cutaneous melanoma over more than 15 years, collectively revealing patterns of skin lymphatic drainage. We aimed to map these data onto a three-dimensional computer model to provide improved visualisation and analysis of lymphatic drainage from sites of cutaneous melanoma.

METHODS

Lymphoscintigraphy data from 5239 patients with cutaneous melanoma were collected between July 27, 1987 and Dec 16, 2005. 4302 of these patients had primary melanoma sites below the neck, and were included in this analysis. From these patients, two-dimensional lymphoscintigraphy data were mapped onto an anatomically based three-dimensional computer model of the skin and lymph nodes. Spatial analysis was done to visualise the relation between primary melanoma sites and the locations of sentinel lymph nodes.

FINDINGS

We created three-dimensional, colour-coded heat maps that showed the drainage patterns from melanoma sites below the neck to individual lymph-node fields and to many lymph-node fields. These maps highlight the inter-patient variability in skin lymphatic drainage, and show the skin regions in which highly variable drainage can occur. To enable interactive and dynamic analysis of these data, we also developed software to predict lymphatic drainage patterns from melanoma skin sites to sentinel lymph-node fields.

INTERPRETATION

The heat maps confirmed that the commonly used Sappey's lines are not effective in predicting lymphatic drainage. The heat maps and the interactive software could be a new resource for clinicians to use in preoperative discussions with patients with melanoma and other skin cancers that can metastasise to the lymph nodes, and could be used in the identification of sentinel lymph-node fields during follow-up of such patients.