Sentinel lymph node assessment in melanoma: current state and future directions

Assessment of sentinel lymph node status is an important step in the evaluation of patients with melanoma for both prognosis and therapeutic management. Pathologists have an important role in this evaluation. The methodologies have varied over time, from the evaluation of dimensions of metastatic burden to determination of the location of the tumour deposits within the lymph node to precise cell counting. However, no single method of sentinel lymph node tumour burden measurement can currently be used as a sole independent predictor of prognosis. The management approach to sentinel lymph node-positive patients has also evolved over time, with a more conservative approach recently recognised for selected cases. This review gives an overview of past and current status in the field with a glimpse into future directions based on prior experiences and clinical trials.

Deep learning detection of melanoma metastases in lymph nodes

BACKGROUND

In melanoma patients, surgical excision of the first draining lymph node, the sentinel lymph node (SLN), is a routine procedure to evaluate lymphogenic metastases. Metastasis detection by histopathological analysis assesses multiple tissue levels with hematoxylin and eosin and immunohistochemically stained glass slides. Considering the amount of tissue to analyze, the detection of metastasis can be highly time-consuming for pathologists. The application of artificial intelligence in the clinical routine has constantly increased over the past few years.

METHODS

In this multi-center study, a deep learning method was established on histological tissue sections of sentinel lymph nodes collected from the clinical routine. The algorithm was trained to highlight potential melanoma metastases for further review by pathologists, without relying on supplementary immunohistochemical stainings (e.g. anti-S100, anti-MelanA).

RESULTS

The established method was able to detect the existence of metastasis on individual tissue cuts with an area under the curve of 0.9630 and 0.9856 respectively on two test cohorts from different laboratories. The method was able to accurately identify tumour deposits>0.1 mm and, by automatic tumour diameter measurement, classify these into 0.1 mm to -1.0 mm and>1.0 mm groups, thus identifying and classifying metastasis currently relevant for assessing prognosis and stratifying treatment.

CONCLUSIONS

Our results demonstrate that AI-based SLN melanoma metastasis detection has great potential and could become a routinely applied aid for pathologists. Our current study focused on assessing established parameters; however, larger future AI-based studies could identify novel biomarkers potentially further improving SLN-based prognostic and therapeutic predictions for affected patients.

The sentinel node invasion level (SNIL) as a prognostic parameter in melanoma

Sentinel lymph node (SN) tumor burden is becoming increasingly important and is likely to be included in future N classifications in melanoma. Our aim was to investigate the prognostic significance of melanoma infiltration of various anatomically defined lymph node substructures. This retrospective cohort study included 1250 consecutive patients with SN biopsy. The pathology protocol required description of metastatic infiltration of each of the following lymph node substructures: intracapsular lymph vessels, subcapsular and transverse sinuses, cortex, paracortex, medulla, and capsule. Within the SN with the highest tumor burden, the SN invasion level (SNIL) was defined as follows: SNIL 1 = melanoma cells confined to intracapsular lymph vessels, subcapsular or transverse sinuses; SNIL 2 = melanoma infiltrating the cortex or paracortex; SNIL 3 = melanoma infiltrating the medulla or capsule. We classified 338 SN-positive patients according to the non-metric SNIL. Using Kaplan-Meier estimates and Cox models, recurrence-free survival (RFS), melanoma-specific survival (MSS) and nodal basin recurrence rates were analyzed. The median follow-up time was 75 months. The SNIL divided the SN-positive population into three groups with significantly different RFS, MSS, and nodal basin recurrence probabilities. The MSS of patients with SNIL 1 was virtually identical to that of SN-negative patients, whereas outgrowth of the metastasis from the parenchyma into the fibrous capsule or the medulla of the lymph node indicated a very poor prognosis. Thus, the SNIL may help to better assess the benefit-risk ratio of adjuvant therapies in patients with different SN metastasis patterns.

Predictors of Nonsentinel Lymph Node Metastasis in Cutaneous Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Although completion lymph node dissection (CLND) is not routinely performed for a positive sentinel lymph node (SLN) anymore, adjuvant therapy depends on the risk factors available from SLN biopsy, including the risk of nonsentinel node metastases (NSNM). A systematic review and meta-analysis was performed in an attempt to identify risk factors that could be used to predict the risk of NSNM.

MATERIALS AND METHODS

Medline, Web of Science, Embase, and Cochrane were searched for articles discussing predictive factors for NSNM. PRISMA guidelines were followed, and RevMan software was used to calculate pooled odds ratios (OR) using the Mantel-Haenszel test.

RESULTS

Fifty publications were suitable for additional analysis. The clinical and primary tumor factors that were consistently identified as risk factors for NSNMs were: age >50, T stage 3 or 4, Clark level IV/V, ulceration, microsatellitosis, lymphovascular invasion, nodular histology, and extremity versus trunk primary tumor location. SLN factors that predicted NSNMs were >1 positive SLN, SLN micrometastatic tumor burden, diameter >2 mm, extracapsular extension, nonsubcapsular location (Dewar), and Rotterdam > 1 mm or ≥ 0.1 mm.

CONCLUSIONS

The findings in this study support that many clinical and pathologic risk factors that can be assessed with SLN biopsy alone can be used to predict the risk of NSNMs. The factors identified in this review should be evaluated in clinical prediction models to predict the risk of NSNMS, a prediction that may be used to select patients for adjuvant therapy in high-risk melanoma.

Photoacoustic tomography for assessment and quantification of cutaneous and metastatic malignant melanoma - A systematic review

BACKGROUND

Photoacoustic tomography (PAT) is an emerging noninvasive imaging technique combining high sensitivity optical absorption contrast, such as melanin, with high-resolution ultrasound for deep tissue imaging. The ability of PAT to provide real-time images of skin structures at depth has been studied for diagnosis of primary and metastatic malignant melanoma (MM).

OBJECTIVE

To provide an overview of the rapidly expanding clinical use of PAT for determination of melanoma thickness and architecture, visualization of metastases in lymph nodes and detection of circulating melanoma cells.

METHODS

Medline, PubMed, EMBASE, Web of Science, Google Scholar, and Cochrane Library were searched for papers using PAT to assess cutaneous malignant melanoma and melanoma metastases in humans or human specimens.

RESULTS

The research resulted in 14 articles which met the search criteria.

CONCLUSIONS

Results from current studies suggest that PAT is a promising tool for assessing both primary and metastatic malignant melanoma in the clinic. The potential of PAT to noninvasively visualize tumour boundaries, as well as assist in the evaluation of metastatic status, could facilitate more effective treatment, resulting in better clearance and reducing the need for additional biopsies. However, larger and methodologically sound studies are warranted.

Sentinel lymph node excision with or without preoperative hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) in melanoma: study protocol for a multicentric randomized controlled trial

Background

Melanoma has become a growing interdisciplinary problem in public health worldwide. According to the World Health Organization, the incidence of melanoma is increasing faster than any other cancer in the world. Because melanoma metastasizes early into the regional lymph nodes, sentinel lymph node excision (SLNE) is included in the current American Joint Committee of Cancer guidelines. However SLNE of melanoma has a high false-negative rate of up to 44%.

Methods

The gold standard for detection and extirpation of the sentinel lymph node is preoperative lymphoscintigraphy. SPECT/CT provides complementary information: the advantages include accurate anatomical localization, identification of false positives, reduction in the number of false negatives, and alteration of the surgical approach. Therefore, sentinel lymph node-SPECT/CT provides valuable information before sentinel lymph node excision and advocates its use in melanoma. We present a multicenter, unblinded superiority randomized controlled trial to compare SPECT/CT-aided SLNE versus standard SLNE in melanoma patients.

Discussion

The primary efficacy endpoint is distant metastasis-free survival. Secondary endpoints comprise overall survival, disease-free survival, rate of local relapses within the follow-up period (false-negative rate of sentinel lymph node), number of positive sentinel lymph nodes (sensitivity, false-positive rate), complication rate, quality of life, quality-adjusted life years, inpatient days, and overall costs during hospital stays.

Trial registration

ClinicalTrials.gov, NCT03683550. Registered on 20 September 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3197-7) contains supplementary material, which is available to authorized users.

Current management of regional lymph nodes in patients with melanoma

The publication of recent randomized trials has prompted a significant shift in both our understanding and the management of patients with melanoma. Here, the current management of the regional lymph nodes in patients with melanoma is discussed. This review focuses on selection for sentinel lymph node biopsy, management of the positive sentinel node, management of the clinically positive node, and the controversy over the therapeutic value of early nodal intervention.

Completion Lymph Node Dissection Based on Risk of Nonsentinel Metastasis in Cutaneous Melanoma of the Head and Neck

Objective

Theoretically, completion lymph node dissection (CNLD) should have the lowest benefit in the absence of nonsentinel lymph node (NSLN) metastases. For this reason, substantial research efforts have attempted to define specific criteria that are associated with a low-enough risk of NSLN positivity so that CLND can be deferred. Our objectives were (1) to identify features associated with low risk of NSLN positivity in sentinel lymph node–positive cutaneous melanoma of the head and neck (CMHN) and (2) to analyze the effect of CLND on 5-year disease-specific survival (DSS) among subgroups stratified by risk of NSLN metastasis.

Study Design

Retrospective analysis of population-based data.

Setting

SEER database.

Subjects and Methods

Patients with sentinel lymph node–positive CMHN were categorized according to lymph node treatment following sentinel lymph node biopsy (SLNB): 210 underwent CLND and 140 deferred. Clinicopathologic characteristics and survival were compared between SLNB+CLND and SLNB-only groups. Survival analyses were stratified by age and characteristics associated with NSLN positivity.

Results

Minimal tumor thickness and nonulceration were associated with lowest risk of positive NSLN ( P < .025). In the subgroup with the lowest risk of metastasis, patients aged <60 years who underwent CLND+SLNB had markedly better DSS than those receiving SLNB only (>90% vs <25%; P < .0025). Paradoxically, in subgroups with a higher risk of NSLN metastasis, DSS was similar whether CLND was performed or not ( P > .25).

Conclusions

Selecting patients for CLND according to risk of NSLN metastasis may be a suboptimal strategy for improving DSS. We believe that CLND should not be withheld on the basis of “low risk” features in CMHN.

[Malignant head and neck melanoma: Part 2: Therapy]

Resection margins of melanomas in the head and neck region often have to be adapted according anatomical circumstances. In the case of thicker primary tumors or after complete resection of locoregional lymph node metastases, adjuvant therapy with interferon-α can be performed; in some cases, adjuvant radiotherapy may also be indicated. In the case of inoperable lymph node or distant metastases, systemic treatment is required. Beside well-established mono- or polychemotherapy regimens, newer targeted therapies with BRAF inhibitors (vemurafenib, dabrafenib), mitogenic-activated protein kinase (MEK) inhibitors (trametinib, binimetinib, and cobimetinib), and kinase inhibitors (imatinib, sunitinib, nilotinib, dasatinib) are also available.

Rare presentations of primary melanoma and special populations: a systematic review

A subset of patients with melanoma present in rare and unique clinical circumstances requiring specific considerations with respect to diagnostic and therapeutic interventions. Herein, we present our review of patients with: (1) primary mucosal melanoma of the head and neck, gastrointestinal, and genitourinary tracts; (2) primary melanoma of the eye; (3) desmoplastic melanoma; (4) subungual melanoma; (5) melanoma in special populations: children, nonwhites, as well as a discussion of familial melanoma.

Update and Review on the Surgical Management of Primary Cutaneous Melanoma

The surgical management of malignant melanoma historically called for wide excision of skin and subcutaneous tissue for any given lesion, but has evolved to be rationally-based on pathological staging. Breslow and Clark independently described level and thickness as determinant in prognosis and margin of excision. The American Joint Committee of Cancer (AJCC) in 1988 combined features from each of these histologic classifications, generating a new system, which is continuously updated and improved. The National Comprehensive Cancer Network (NCCN) has also combined several large randomized prospective trials to generate current guidelines for melanoma excision as well. In this article, we reviewed: (1) Breslow and Clark classifications, AJCC and NCCN guidelines, the World Health Organization's 1988 study, and the Intergroup Melanoma Surgical Trial; (2) Experimental use of Mohs surgery for in situ melanoma; and (3) Surgical margins and utility and indications for sentinel lymph node biopsy (SLNB) and lymphadenectomy. Current guidelines for the surgical management of a primary melanoma of the skin is based on Breslow microstaging and call for cutaneous margins of resection of 0.5 cm for MIS, 1.0 cm for melanomas ≤1.0 mm thick, 1-2 cm for melanoma thickness of 1.01-2 mm, 2 cm margins for melanoma thickness of 2.01-4 mm, and 2 cm margins for melanomas >4 mm thick. Although the role of SLNB, CLND, and TLND continue to be studied, current recommendations include SLNB for Stage IB (includes T1b lesions ≤1.0 with the adverse features of ulceration or ≥1 mitoses/mm²) and Stage II melanomas. CLND is recommended when sentinel nodes contain metastatic deposits.

Comparison of sentinel lymph node micrometastatic tumor burden measurements in melanoma

BACKGROUND

Multiple methods have been proposed to classify the micrometastatic tumor burden in sentinel lymph nodes (SLN) for melanoma. The purpose of this study was to determine the classification scheme that best predicts nonsentinel node (NSN) metastasis, disease-free survival (DFS), and overall survival (OS).

STUDY DESIGN

A single reviewer reanalyzed tumor-positive SLN from a multicenter, prospective clinical trial of patients with melanoma ≥ 1.0 mm Breslow thickness who underwent SLN biopsy. The following micrometastatic disease burden measurements were recorded: Starz classification, Dewar classification (microanatomic location), maximum diameter of the largest focus of metastasis, maximum tumor area, and sum of all diameters. Univariate and multivariate models and Kaplan-Meier analysis were used to evaluate each classification system.

RESULTS

We reviewed 204 tumor-positive SLNs from 157 patients. On univariate analysis, all criteria except Starz classification were statistically significant risk factors for NSN metastasis. On multivariate analysis, including Breslow thickness, ulceration, age, sex, and NSN status, maximum diameter (using a cut-off of 3 mm) was the only classification system that was an independent risk factor predicting DFS (hazard ratio 2.31, p = 0.0181) and OS (hazard ratio 3.53, p = 0.0005). By Kaplan-Meier analysis, DFS and OS were significantly different among groups using maximum diameter cut-offs of 1 and 3 mm.

CONCLUSIONS

Maximum tumor diameter outperformed other measurements of metastatic tumor burden, including microanatomic tumor location (Dewar classification), Starz classification, maximum tumor area, and sum of all diameters for prediction of survival. Maximum tumor diameter is a simple method of assessing micrometastatic tumor burden that should be reported routinely.

Incidence and location of positive nonsentinel lymph nodes in head and neck melanoma

BACKGROUND

The complex lymphatic drainage in the head and neck makes sentinel lymph node biopsy (SLNB) for melanomas in this region challenging. This study describes the incidence, and location of additional positive nonsentinel lymph nodes (NSLN) in patients with cutaneous head and neck melanoma following a positive SLNB.

METHODS

A retrospective review was performed using a single institution prospective database. Patients with a primary melanoma in the head or neck with a positive cervical SLNB were identified. The lymphadenectomy specimen was divided intraoperatively into lymph node levels I-V, and NSLN status determined for each level.

RESULTS

Of 387 patients with melanoma of the head and neck who underwent cervical SLNB, 54 had a positive SLN identified (14%). Thirty six patients (67%) underwent immediate completion lymph node dissection (CLND) of whom eight patients (22%) had a positive NSLN. The remaining 18 patients (33%) did not undergo CLND and were observed. Half of positive NSLNs (50%) were in the same lymph node level as the SLN and 33% were in an immediately adjacent level; only two patients were found to have NSLNs in non-adjacent levels. The only factor predictive of NSLN involvement was the size of the tumor deposit in the SLN>0.2 mm (p = 0.05). Superficial parotidectomy at CLND revealed metastatic melanoma only in patients with a positive parotid SLN.

CONCLUSIONS

A positive NLSN was identified in 22% of patients undergoing CLND after a positive SLNB. The majority of positive NSLNs are found within or immediately adjacent to the nodal level containing the SLN.

The prognostic significance of sentinel node tumour burden in melanoma patients: an international, multicenter study of 1539 sentinel node-positive melanoma patients

INTRODUCTION

Sentinel node (SN) biopsy (SNB) and completion lymph node dissection (CLND) when SN-positive have become standard of care in most cancer centres for melanoma. Various SN tumour burden parameters are assessed to determine the heterogeneity of SN-positivity. The aim of the present study was to validate the prognostic significance of various SN tumour burden micromorphometric features and classification schemes in a large cohort of SN-positive melanoma patients.

METHODS

In 1539 SN-positive patients treated between 1993 and 2008 at 11 melanoma treatment centres in Europe and Australia, indices of SN tumour burden (intranodal location, tumour penetrative depth (TPD) and maximum size of SN tumour deposits) were evaluated.

RESULTS

Non-subcapsular location, increasing TPD and increasing maximum size were all predictive factors for non-SN (NSN) status and were independently associated with poorer melanoma-specific survival (MSS). Patients with subcapsular micrometastases <0.1mm in maximum dimension had the lowest frequency of NSN metastasis (5.5%). Despite differences in SN biopsy protocols and clinicopathologic features of the patient cohorts (between centres), most SN parameters remained predictive in individual centre populations. Maximum SN tumour size>1mm was the most reliable and consistent parameter independently associated with higher non-SN-positivity, poorer disease-free survival (DFS) and poorer MSS.

CONCLUSIONS

In this large retrospective, multicenter cohort study, several parameters of SN tumour burden including intranodal location, TPD and maximum size provided prognostic information, but their prognostic significance varied considerably between the different centres. This could be due to sample size limitations or to differences in SN detection, removal and examination techniques.

Completion lymph node dissection after a positive sentinel node: no longer a must?

PURPOSE OF REVIEW

Sentinel node biopsy (SNB) for primary melanoma is accepted worldwide as a diagnostic procedure. When sentinel node positive, the invasive completion lymph node dissection (CLND) is usually performed. Approximately 20% of CLND patients have nonsentinel node (NSN) metastases. The therapeutic benefit is unknown. This review analyzed the necessity of CLND in sentinel node positive patients.

RECENT FINDINGS

Prognosis of sentinel node positive patients is highly heterogeneous. The Rotterdam and Dewar criteria and S-classification are important sentinel node tumor burden criteria to stratify melanoma patients for prognosis and risk of NSN metastases. Patients with less than 0.1 mm metastases seem to have similar prognosis as sentinel node negative patients, especially when located in the subcapsular area. This depends on the use of an extensive sentinel node pathology protocol identifying possibly clinically irrelevant micrometastases.

SUMMARY

Consensus on the sentinel node pathology work-up and analysis protocols are crucial for correct risk stratification and for clinical decision-making. Primary and sentinel node tumor burden parameters and patient comorbidities should be taken into consideration when offering CLND to an individual patient. In the future, prospective studies such as the MSLT-II and the EORTC 1208 (Minitub) will provide answers to whether CLND has a therapeutic benefit and to which patients might safely be spared CLND.

Is complete lymph node dissection after a positive sentinel lymph node biopsy for cutaneous melanoma always necessary? A meta-analysis

BACKGROUND

The current recommendation for patients with cutaneous melanoma and a positive sentinel lymph node (SLN) biopsy is a complete lymph node dissection (CLND). However, metastatic melanoma is not present in approximately 80% of CLND specimens. A meta-analysis was performed to identify the clinicopathological variables most predictive of non-sentinel node (NSN) metastases when the sentinel node is positive in patients with melanoma.

METHODS

A systematic search was conducted using MEDLINE, PubMed, EMBASE, Current Contents Connect, Cochrane library, Google scholar, Science Direct, and Web of Science. The search identified 54 relevant articles reporting the frequency of NSN metastases in melanoma. Original data was abstracted from each study and used to calculate a pooled odds ratio (OR) and 95% confidence interval (95% CI).

FINDINGS

The pooled estimates that were found to be significantly associated with the high likelihood of NSN metastases were: ulceration (OR: 1.88, 95% CI: 1.53-2.31), satellitosis (OR: 3.25, 95% CI: 1.86-5.66), neurotropism (OR: 2.51, 95% CI: 1.39-4.53), >1 positive SLN (OR: 1.77, 95% CI: 1.2-2.62), Starz 3 (old) (OR: 1.83, 95% CI: 0.89-3.76), Angiolymphatic invasion (OR: 2.46, 95% CI: 1.34-4.54), extensive location (OR: 2.22, 95% CI: 1.74-2.81), macrometastases >2 mm (OR: 1.95, 95% CI: 1.61-2.35), extranodal extension (OR: 3.38, 95% CI: 1.79-6.40) and capsular involvement (OR: 3.16, 95% CI: 1.37-7.27). There were 3 characteristics not associated with NSN metastases: subcapsular location (OR: 0.51, 95% CI: 0.38-0.67), Rotterdam Criteria <0.1 mm (OR: 0.29, 95% CI: 0.17-0.50) and Starz I (new) (OR: 0.44, 95% CI: 0.22-0.91). Other variables including gender, Breslow thickness 2-4 mm and extremity as primary site were found to be equivocal.

INTERPRETATION

This meta-analysis provides evidence that patients with low SLN tumor burden could probably be spared the morbidity associated with CLND. We identified 9 factors predictive of non-SLN metastases that should be recorded and evaluated routinely in SLN databases. However, further studies are needed to confirm the standard criteria for not performing CLND.

Assessment of a new scoring system for predicting non-sentinel node positivity in sentinel node-positive melanoma patients

BACKGROUND

When completion lymph node dissection (CLND) is performed in sentinel node (SN)-positive melanoma patients, a positive non-sentinel node (NSN) is found in approximately 20% of them. Recently, Murali et al. proposed a new scoring system (non-sentinel node risk score, N-SNORE) to predict the risk of NSN positivity in SN-positive patients. The objectives of the current study were to identify factors predicting NSN positivity and to assess the validity of the N-SNORE in an independent patient cohort.

METHODS

All SN-positive patients who underwent CLND at a single institution between 1995 and 2010 were analyzed. Characteristics of the patient, primary melanoma, and SN(s) were tested for association with NSN positivity. Missing values were reconstructed using multiple imputation to enable multivariable analysis.

RESULTS

CLND revealed positive NSNs in 30 (23%) of 130 SN-positive patients. Primary melanoma regression (p = 0.03) was independently associated with NSN positivity. After adjustment because of missing data on perinodal lymphatic invasion, N-SNORE proved to be a significant stratification model in our patient cohort (p = 0.003): 5.9% NSN positivity in the very low risk category and 75.0% NSN positivity in the very high risk category.

CONCLUSIONS

Presence of regression in the primary melanoma was independently associated with a higher risk of NSN positivity. The slightly modified N-SNORE scoring system provided useful stratification of the risk for NSN positivity. However, lack of perinodal lymphatic invasion data may have reduced its predictive value.

Sentinel lymph node biopsy in patients with thin primary cutaneous melanoma

OBJECTIVES

To determine the rate and clinicopathologic factors predictive of sentinel lymph node (SLN) positivity, regional lymph node recurrence, and survival in a large series of patients with thin primary cutaneous melanoma who underwent SLN biopsy (SLNB).

METHODS

Patients with thin (≤1 mm) melanomas who underwent SLNB between 1992 and 2009 at Melanoma Institute Australia were identified from the Melanoma Institute Australia database. The association of clinicopathologic features with SLN status, lymph node recurrence, and survival was analyzed.

RESULTS

In 432 patients [226 men, 206 women; median age 49.5 years (range: 14.4-85.0 years)], SLNB was positive for metastatic melanoma in 29 (6.7%) patients. No SLN positivity was detected in 37 patients with primary tumor thickness 0.50 mm or less. Breslow thickness (P = 0.012) and presence of lymphovascular invasion (P = 0.018) were the only factors significantly associated with SLN positivity. Regional lymph node recurrence was significantly more common in tumors located in the head/neck region (4/33, 12%) than in extremities (3/245, 1.2%) and trunk (2/154, 1.3%) (P < 0.001). Primary tumor mitotic rate was a significant predictor of melanoma-specific survival (Hazard Ratio [HR] = 1.2, 95% confidence interval: 1.09-1.35, P < 0.001).

CONCLUSIONS

There is a low but significant rate of SLN positivity in patients with primary melanomas 0.51 to 1.0 mm in thickness. Given its prognostic importance, SLNB should be considered in such patients, particularly if there is lymphatic permeation by melanoma at the primary tumor site. More frequent regional node field recurrences in patients with head/neck primary tumors may be a consequence of complex lymphatic drainage patterns in this region.

Sentinel lymph nodes containing very small (<0.1 mm) deposits of metastatic melanoma cannot be safely regarded as tumor-negative

BACKGROUND

Some authors have suggested that patients with very small (<0.1 mm) deposits of metastatic melanoma in sentinel lymph nodes (SLNs) should be considered SLN-negative, whereas others have reported that such patients can have adverse long-term outcomes. The aims of the present study were to determine whether extensive sectioning of SLNs resulted in more accurate categorization of histologic features of tumor deposits and to assess prognostic associations of histologic parameters obtained using more intensive sectioning protocols.

METHODS

From patients with a single primary cutaneous melanoma who underwent SLN biopsy between 1991 and 2008, those in which the maximum size of the largest tumor deposit (MaxSize) in SLNs was <0.1 mm in the original sections were identified. Five batches of additional sections were cut from the SLN tissue blocks at intervals of 250 μm. The 1st batch was cut from the blocks without any trimming; these sections were therefore immediately adjacent to the original sections. Each batch included 5 sequential sections, the 1st and 5th stained with hematoxylin-eosin, and the 2nd, 3rd, and 4th stained immunohistochemically with S-100, HMB-45, and Melan-A, respectively. In each batch of sections, the following histologic features of tumor deposit(s) in the SLNs were evaluated: MaxSize; tumor penetrative depth (TPD) (defined as the maximum depth of tumor deposit(s) from the inner margin of the lymph node capsule), and intranodal location (classified as subcapsular if the tumor deposit(s) were confined to the subcapsular zone or parenchymal if there was any involvement of the nodal parenchyma beyond the subcapsular zone). The measured histologic parameters were compared in each batch of sections. The association of histologic parameters with overall survival was assessed for the parameters measured in each batch of sections.

RESULTS

There were 20 eligible patients (15 females, 5 males, median age 60 years). After a median follow-up duration of 40 months, 4 patients had died from melanoma and 2 patients of unknown causes. Completion lymph node dissection (CLND) was performed in 13 cases (65%) and was negative in all cases. Relative to the measured values on the original sections, all 3 parameters were upstaged in subsequent batches of sections, but no further upstaging of MaxSize, TPD, or location was seen beyond batch 3, batch 4, and batch 2, respectively. Increasing MaxSize was associated with significantly poorer overall survival in batches 1, 2, and 3. Parenchymal involvement was significantly associated with poorer survival in batches 2-5. TPD was not significantly associated with overall survival.

CONCLUSIONS

The results of this study indicate that very small (<0.1 mm) deposits of melanoma in SLNs may be associated with adverse clinical outcomes and that this is due, at least in part, to the underestimation of SLN tumor burden in the initial sections. Our evidence does not support clinical decision-making on the assumption that patients with very small melanoma deposits in SLNs have the same outcome as those who are SLN-negative.

Prognosis in patients with sentinel node-positive melanoma is accurately defined by the combined Rotterdam tumor load and Dewar topography criteria

PURPOSE

Prognosis in patients with sentinel node (SN)-positive melanoma correlates with several characteristics of the metastases in the SN such as size and site. These factors reflect biologic behavior and may separate out patients who may or may not need additional locoregional and/or systemic therapy.

PATIENTS AND METHODS

Between 1993 and 2008, 1,080 patients (509 women and 571 men) were diagnosed with tumor burden in the SN in nine European Organisation for Research and Treatment of Cancer (EORTC) melanoma group centers. In total, 1,009 patients (93%) underwent completion lymph node dissection (CLND). Median Breslow thickness was 3.00 mm. The median follow-up time was 37 months. Tumor load and tumor site were reclassified in all nodes by the Rotterdam criteria for size and in 88% by the Dewar criteria for topography.

RESULTS

Patients with submicrometastases (< 0.1 mm in diameter) were shown to have an estimated 5-year overall survival rate of 91% and a low nonsentinel node (NSN) positivity rate of 9%. This is comparable to the rate in SN-negative patients. The strongest predictive parameter for NSN positivity and prognostic parameter for survival was the Rotterdam-Dewar Combined (RDC) criteria. Patients with submicrometastases that were present in the subcapsular area only, had an NSN positivity rate of 2% and an estimated 5- and 10-year melanoma-specific survival (MSS) of 95%.

CONCLUSION

Patients with metastases < 0.1 mm, especially when present in the subcapsular area only, may be overtreated by a routine CLND and have an MSS that is indistinguishable from that of SN-negative patients. Thus the RDC criteria provide a rational basis for decision making in the absence of conclusions provided by randomized controlled trials.

Non-Sentinel Node Risk Score (N-SNORE): a scoring system for accurately stratifying risk of non-sentinel node positivity in patients with cutaneous melanoma with positive sentinel lymph nodes

PURPOSE

Sentinel node (SN) biopsy allows identification of patients with melanoma at risk of further metastatic disease in regional non-sentinel nodes (NSN). We investigated clinicopathologic factors that predict NSN positivity in an attempt to identify patients who may be safely spared completion lymph node dissection (CLND).

PATIENTS AND METHODS

Clinicopathologic factors previously shown to be predictive of NSN positivity were analyzed in 409 patients with SN-positive disease (309 of whom underwent CLND) managed at a single melanoma center. A weighted score Non-Sentinel Node Risk Score [N-SNORE] incorporating predictive factors was derived, and the efficacy of N-SNORE at stratifying risk of NSN involvement was studied.

RESULTS

Factors independently predictive of NSN positivity included primary tumor regression, proportion of harvested SNs involved by melanoma (%PosSN), sex (trend), and SN tumor burden indices (maximum size of largest deposit [MaxSize], % cross-sectional area of SN occupied by tumor, tumor penetrative depth, intranodal location of tumor) and perinodal lymphatic invasion (PLI). Of SN tumor burden criteria, MaxSize was the strongest predictor. N-SNORE was the sum of scores for five parameters: sex (female = 0, male = 1), regression (absent = 0, present = 2), %PosSN (absent = 0, present = 2), MaxSize (≤ 0.5 mm = 0, 0.51 to 2.00 mm = 1, 2.01 to 10.00 mm = 2, > 10.00 mm = 3), and PLI (absent = 0, present = 3). N-SNOREs of 0, 1 to 3, 4 to 5, 6 to 7, and ≥ 8 were associated with very low (0%), low (5% to 10%), intermediate (15% to 20%), high (40% to 50%), and very high (70% to 80%) risks of NSN involvement.

CONCLUSION

A weighted score (N-SNORE) based on clinicopathologic characteristics accurately stratifies risk of NSN involvement in patients with melanoma. If validated in future studies, N-SNORE will better predict prognosis, aid in management decisions, and stratify patient groups for entry into clinical trials.

The prognostic significance of nonsentinel lymph node metastasis in melanoma

BACKGROUND

We hypothesized that metastasis beyond the sentinel lymph nodes (SLN) to the nonsentinel nodes (NSN) is an important predictor of survival.

MATERIALS AND METHODS

Analysis was performed of a prospective multi-institutional study that included patients with melanoma ≥ 1.0 mm in Breslow thickness. All patients underwent SLN biopsy; completion lymphadenectomy was performed for all SLN metastases. Disease-free survival (DFS) and overall survival (OS) were computed by Kaplan-Meier analysis; univariate and multivariate analyses were performed to identify factors associated with differences in survival among groups.

RESULTS

A total of 2335 patients were analyzed over a median follow-up of 68 months. We compared 3 groups: SLN negative (n = 1988), SLN-only positive (n = 296), and both SLN and NSN positive (n = 51). The 5-year DFS rates were 85.5, 64.8, and 42.6% for groups 1, 2, and 3, respectively (P < 0.001). The 5-year OS rates were 85.5, 64.9, and 49.4%, respectively (P < 0.001). On univariate analysis, predictors of decreased OS included: SLN metastasis, NSN metastasis, increased total number of positive LN, increased ratio of positive LN to total LN, increased age, male gender, increased Breslow thickness, presence of ulceration, Clark level ≥ IV, and axial primary site (in all cases, P < 0.01). When the total number of positive LN and NSN status were evaluated using multivariate analysis, NSN status remained statistically significant (P < 0.01), while the total number of positive LN and LN ratio did not.

CONCLUSIONS

NSN melanoma metastasis is an independent prognostic factor for DFS and OS, which is distinct from the number of positive lymph nodes or the lymph node ratio.

Sentinel node positive melanoma patients: prediction and prognostic significance of nonsentinel node metastases and development of a survival tree model

BACKGROUND

Completion lymph node dissection (CLND) following positive sentinel node biopsy (SNB) for melanoma detects additional nonsentinel node (NSN) metastases in approximately 20% of cases. This study aimed to establish whether NSN status can be predicted, to determine its effect on survival, and to develop survival tree models for the sentinel node (SN) positive population.

MATERIALS AND METHODS

Sydney Melanoma Unit (SMU) patients with at least 1 positive SN, meeting inclusion criteria and treated between October 1992 and June 2005, were identified from the Unit database. Survival characteristics, potential predictors of survival, and NSN status were assessed using the Kaplan-Meier method, Cox regression model, and logistic regression analyses, respectively. Classification tree analysis was performed to identify groups with distinctly different survival characteristics.

RESULTS

A total of 323 SN-positive melanoma patients met the inclusion criteria. On multivariate analysis, age, gender, primary tumor thickness, mitotic rate, number of positive NSNs, or total number of positive nodes were statistically significant predictors of survival. NSN metastasis, found at CLND in 19% of patients, was only predicted to a statistically significant degree by ulceration. Multivariate analyses demonstrated that survival was more closely related to number of positive NSNs than total number of positive nodes. Classification tree analysis revealed 4 prognostically distinct survival groups.

CONCLUSIONS

Patients with NSN metastases could not be reliably identified prior to CLND. Prognosis following CLND was more closely related to number of positive NSNs than total number of positive nodes. Classification tree analysis defined distinctly different survival groups more accurately than use of single-factor analysis.

Sentinel lymph node biopsy and melanoma: 2010 update Part II

This article will discuss the evidence for and against the therapeutic efficacy of early removal of potentially affected lymph nodes, morbidity associated with sentinel lymph node biopsy and completion lymphadenectomy, current guidelines regarding patient selection for sentinel lymph node biopsy, and the remaining questions that ongoing clinical trials are attempting to answer. The Sunbelt Melanoma Trial and the Multicenter Selective Lymphadenectomy Trials I and II will be discussed in detail.

LEARNING OBJECTIVES

At the completion of this learning activity, participants should be able to discuss the data regarding early surgical removal of lymph nodes and its effect on the overall survival of melanoma patients, be able to discuss the potential benefits and morbidity associated with complete lymph node dissection, and to summarize the ongoing trials aimed at addressing the question of therapeutic value of early surgical treatment of regional lymph nodes that may contain micrometastases.

Interobserver reproducibility of histologic parameters of melanoma deposits in sentinel lymph nodes: implications for management of patients with melanoma

BACKGROUND

: Histologic parameters of melanoma deposits in sentinel lymph nodes (SLNs) have been shown to be predictive of clinical outcome and the presence or absence of tumor in non-SLNs, but assessment of these parameters is prone to interobserver variation.

METHODS

: Histologic sections of 44 SLNs containing metastatic melanoma were examined by 7 pathologists. Parameters assessed included cross-sectional area of tumor deposits, cross-sectional area of SLNs, percentage of SLN area involved by tumor calculated from the 2 previous parameters, estimated percentage of SLN area involved by tumor, tumor penetrative depth, location of tumor within the SLN, and presence of extracapsular spread. Levels of interobserver agreement were measured by using intraclass correlation coefficients (ICC).

RESULTS

: There was good to excellent interobserver agreement on measurement of quantitative parameters: maximal size of largest tumor deposits, calculated area of 3 largest tumor deposits, percentage of the area of SLN involved by tumor, and tumor penetrative depth (ICC, 0.88, 0.73, 0.68, and 0.83, respectively). There was moderate agreement on the evaluation of subcapsular versus nonsubcapsular location of tumor deposits (ICC = 0.50). Agreement on assessment of extracapsular spread was fair (ICC = 0.39).

CONCLUSIONS

: Assessment of some of the quantitative parameters was highly reproducible between pathologists. However, evaluation of the location of tumor deposits within SLNs and assessment of extracapsular spread was less reproducible. Clearer definitions and training can be expected to improve the reproducibility of assessment. These results have important implications for reliability and reproducibility of these parameters in staging, prediction of outcome, and clinical management of melanoma patients. Cancer 2009. (c) 2009 American Cancer Society.

Prognostic significance of a positive nonsentinel lymph node in cutaneous melanoma

PURPOSE

Sentinel lymph node (SLN) biopsy provides important prognostic information for patients with cutaneous melanoma. There may be additional prognostic significance to melanoma spreading from the SLN to nonsentinel lymph nodes (NSLN). We examined the implications of a positive NSLN for overall and distant disease-free survival.

METHODS

Using a prospectively maintained, Institutional Review Board-approved melanoma database we studied patients who had a cutaneous melanoma, a positive SLN, and a completion lymph node dissection (CLND). Survival was determined using a combination of hospital records and the Social Security Death Index (SSDI). Univariate and multivariate Cox regression analysis was performed to further characterize predictors of overall and distant disease-free survival. Kaplan-Meier analysis was used to generate survival curves.

RESULTS

A total of 429 patients with positive SLN biopsies were identified, with at least one positive NSLN identified in 71 (17%). Median follow-up time was 36.8 months. Presence of a positive NSLN was significantly associated with poor outcome, although long-term survival was possible. Presence of ulceration, high mitotic rate, angiolymphatic invasion, total number of positive nodes, and volume of disease>1% in the SLN were significant predictors of survival on univariate analysis, but lost significance on multivariate. Multivariate Cox analysis revealed several predictors of overall survival: increasing age [hazard ratio (HR) 1.04, P<0.01], Breslow depth (HR 1.76, P<0.01), presence of extracapsular extension in the SLN (HR 2.39, P<0.01), and positive NSLN (HR 1.92, P<0.01).

CONCLUSION

Among node-positive melanoma patients, presence of a positive NSLN is a highly significant poor prognostic sign, even after considering the total number of positive nodes and volume of disease in the SLN. CLND after a positive SLN provides this important prognostic information.

Sentinel lymph node biopsy for melanoma: aspects of pathologic assessment

Sentinel lymph node (SLN) biopsy affords an accurate, minimally invasive means of staging and determining prognosis in patients with melanoma and for identifying those patients who may benefit from complete regional lymph node dissection. Careful and accurate histopathologic assessment of SLNs is critical to achieving optimal reliability of the technique. Micromorphometric parameters of melanoma deposits in SLNs have been shown to be predictive of regional non-SLN involvement and of clinical outcomes. Several non-histopathologic methods of SLN evaluation have been investigated, and while some of them show promise for the future, excision and histopathologic examination currently remains the gold standard for the evaluation of SLNs.