Detection of occult melanoma cells in paraffin-embedded histologically negative sentinel lymph nodes using a reverse transcriptase polymerase chain reaction assay

Sentinel Lymph Node Biopsy to Stage Patients with Cutaneous Melanoma at the National Cancer Institute of Naples. Results from 240 Sentinel Node Biopsies

Aimsand background

The presence of lymph node metastases in patients with cutaneous melanoma represents the basis for correct therapy planning and is the most powerful prognostic factor to evaluate overall survival at diagnosis.

Methods and Study Design

Since 1992, when Dr Morton published his first experience, the sentinel lymph node (SLN) biopsy technique seems to have resolved this matter by correctly staging patients. We analyzed our data from 240 SLN biopsies performed in the last five years at the National Cancer Institute of Naples, evaluating the total identification rate and the nodal recurrence rate, and compared them with the preliminary data of the MSLT (melanoma sentinel lymph node trial).

Results

Of all SLNs evaluated 18.5% were micrometastatic and 14% were identified by immunohistochemical staining. Forty-one patients had metastatic SLNs and nodal dissection of the positive basins revealed no other tumor-positive lymph nodes in more than 80% of them. All patients with a Breslow thickness of less than 2 mm had micrometastases only in the SLN, while with increasing thickness two, three or more positive nodes were found. Among SLN-negative patients nine (4%) developed lymph node recurrence in the previously treated basin and were therefore considered as false negative SLN biopsies.

Conclusions

The prognostic value of SLN biopsy needs to be confirmed by the final results of the MSLT evaluating the therapeutic use of this procedure in patients with a Breslow thickness of less than 2 mm and its possible impact on the course of the disease.

Indocyanine green fluorescence-navigated sentinel node biopsy showed higher sensitivity than the radioisotope or blue dye method, which may help to reduce false-negative cases in skin cancer

BACKGROUND AND OBJECTIVES

Although sentinel lymph node (SLN) biopsy using radioisotope (RI) and blue dye (BD) achieved a high detection rate, approximately 5% of melanomas with negative SLNs develop nodal metastasis. We tested a new lymphatic navigation method using indocyanine green fluorescence imaging (ICG-FI) to detect such "occult" SLNs.

METHODS

Thirty-four skin cancer patients received SLN biopsy with the following three methods: RI (99Tc-tin colloid), BD (2% patent blue), and ICG (0.5% indocyanine green). Lymph nodes detected by any of the three methods were counted as SLNs.

RESULTS

ICG-FI detected more SLNs in 8 out of the 34 cases (24%). The average numbers of SLNs detected by ICG-FI, RI, and BD were 2.18, 1.76, and 1.73, respectively. Interestingly, ICG-FI not only detected more SLNs in one basin (ICG-FI: 1.64, RI: 1.50, and BD: 1.51 SLNs per basin), but also detected additional SLNs in other basins (ICG-FI: 1.32, RI: 1.18, and BD: 1.15 basins per case).

CONCLUSION

ICG-FI detected SLNs more efficiently than did the conventional methods, and these "occult" SLNs may offer an explanation for some false-negative cases. We recommend using ICG-FI in addition to a conventional method to reduce the risk of overlooking these "occult" SLNs.

Increased detection of metastatic melanoma in pediatric sentinel lymph node biopsies using RT-PCR on paraffin-embedded tissue

Sentinel lymph node (SLN) biopsy has become integral in the staging of patients with melanoma, and entails detailed histologic examination with immunohistochemistry. Reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosinase transcripts has been used to increase sensitivity but requires a dedicated piece of tissue that does not undergo histologic examination. We developed a nested RT-PCR assay for tyrosinase applicable on paraffin-embedded tissue and applied this to a series of SLNs from pediatric patients with melanoma. Thirty-six SLNs from 4 females and 4 males were included in the study. Eight lymph nodes with reactive changes were included as controls. SLNs were examined histologically and immunohistochemically for S100, tyrosinase, and MART1. Seven patients had between 1 and 4 morphologically-positive SLNs and one patient had negative SLNs (HISTO+; 12/36, 33%). Three lymph nodes were excluded from molecular analysis owing to inadequate RNA, and 29 of the remaining 33 nodes were positive (MOL+; 88%). All patients had at least 1 SLN positive by RT-PCR. Twelve were HISTO+/MOL+; 17 were HISTO-/MOL+; and 4 were HISTO-/MOL-. All control lymph nodes were negative for tyrosinase transcripts. The application of RT-PCR for tyrosinase to paraffin-embedded tissue significantly increased the number of positive SLNs and upstaged one patient from negative to positive. The prognostic implications of such findings require further investigation, especially in the pediatric age group. Nonetheless, this technique provides a useful tool to determine the clinical significance of RT-PCR positivity in melanoma SLNs.

BeadArray-based solutions for enabling the promise of pharmacogenomics

A "one-size-fits-all" approach continues to characterize today's healthcare paradigm. But emergent rules, information, genomics tools, and economics are driving a fundamental and inevitable shift to a more personalized world of medicine. In this new world, the interests of insurers, regulators, suppliers, healthcare providers, and most important, patients, will have converged. The new goal will be the right treatment for the right individual at the right time. In this world, personalized medicine, through pharmacogenomics (PGx), will be the new healthcare paradigm. We will briefly examine healthcare trends and current opportunities for PGx development. We will then demonstrate how microarray technologies--among them bead-based approaches--have emerged as a key enabler for bringing home the promise of PGx.

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.

Issues affecting molecular staging in the management of patients with melanoma

Prediction of metastatic potential remains one of the main goals to be pursued in order to better assess the risk subgroups of patients with melanoma. Detection of occult melanoma cells in peripheral blood (circulating metastatic cells [CMC]) or in sentinel lymph nodes (sentinel node metastatic cells [SNMC]), could significantly contribute to better predict survival in melanoma patients. An overview of the numerous published studies indicate the existence of several drawbacks about either the reliability of the approaches for identification of occult melanoma cells or the clinical value of CMC and SNMC as prognostic factors among melanoma patients. In this sense, characterization of the molecular mechanisms involved in development and progression of melanoma (referred to as melanomagenesis) could contribute to better classify the different subsets of melanoma patients. Increasing evidence suggest that melanoma develops as a result of accumulated abnormalities in genetic pathways within the melanocytic lineage. The different molecular mechanisms may have separate roles or cooperate during all evolutionary phases of melanocytic tumourigenesis, generating different subsets of melanoma patients with distinct aggressiveness, clinical behaviour, and response to therapy. All these features associated with either the dissemination of occult metastatic cells or the melanomagenesis might be useful to adequately manage the melanoma patients with different prognosis as well as to better address the different melanoma subsets toward more appropriate therapeutic approaches.

Sentinel lymph node molecular ultrastaging in patients with melanoma: a systematic review and meta-analysis of prognosis

PURPOSE

Molecular biology-based ultrastaging of cancer is already part of the standard management of patients with hematologic malignancies, whereas the evidence for solid tumors is much more debated. Polymerase chain reaction (PCR) -based detection of melanoma cells in sentinel lymph nodes (SLN) of patients with melanoma represents an appealing prognostic tool. However, no consensus exists on the clinical implementation of this prognostic indicator for the management of these patients.

METHODS

Twenty-two studies enrolling 4,019 patients who underwent SLN biopsy for clinical stage I to II cutaneous melanoma were reviewed. Correlation of PCR status with TNM stage, disease recurrence rates, and survival was assessed by means of association statistics and formal meta-analysis, respectively.

RESULTS

PCR status correlated with both TNM stage (stage I to II v III; PCR positivity, 95.1% v 46.6%; P < .0001) and disease recurrence (PCR positive v negative; relapse rate, 16.8% v 8.7%; P < .0001). PCR positivity was also associated with worse overall (hazard ratio [HR], 5.08; 95% CI, 1.83 to 14.08; P = .002) and disease-free (HR, 3.41; 95% CI, 1.86 to 6.24; P < .0001) survival. Statistical heterogeneity was significant, underscoring the variability among overall effect estimates across studies; metaregression and subgroup analysis did not identify clear-cut sources of heterogeneity, although some study design variables were suggested as potential causes.

CONCLUSION

PCR status of SLN appears to have a clinically valuable prognostic power in patients with melanoma. Although the heterogeneity of the studies so far published warrants caution to avoid overestimating the favorable results of pooled data, our findings strongly support additional investigation in this field.

Pathological Evaluation of Sentinel Lymph Nodes

The sentinel lymph nodes are the most likely site of nodal metastasis. Their focused analysis results in upstaging cancers, although the extra yield from a more intensive work-up is generally dominated by micrometastases and isolated tumor cells. Nodal staging is generally done to reflect systemic spread of solid tumors and guide treatment accordingly. However, in general, the two processes of haematogenous and lymphogenic spread are not causally interrelated, and the extrapolation from low-volume nodal involvement to systemic involvement and therapeutic consequences of this extrapolation are still under investigation.

The role of sentinel lymph node biopsy in the management of melanoma

During the last 2 decades, the development and wide acceptance of SLN biopsy have affected the management of melanoma profoundly. This technique represents a considerable improvement in the ability to evaluate the tumor status of the regional lymph node basin, which is the most important predictor of survival in patients who have melanoma. Histopathologic and molecular assessment of the SLN has enhanced the detection of clinically occult nodal metastases, thereby distinguishing patients who might benefit from immediate lymphadenectomy from those for whom this procedure is unlikely to be helpful. This technique also identifies patients who would be candidates for clinical trials of adjuvant therapy. Centers can offer SLN biopsy without routine CLND once they reach a level of proficiency that usually corresponds to a learning phase of 55 cases. The role of molecular technology in the identification and analysis of the SLN remains to be established. Although molecular evidence of SLN metastasis has been identified in patients who have early-stage melanoma, its clinical relevance cannot be determined until marker selection is improved. The markers presently under study lack sensitivity and specificity. The role of molecular biomarkers can be validated only through large, multicenter, randomized. controlled trials such as the MSLT-II, a trial that will determine the benefit of multimarker RT-PCR assay in SLN specimens. SLN offers a promising future in staging lymph nodes and will improve the management of patients who have melanoma. Although SLN biopsy has become widely accepted as a minimally invasive technique of staging regional lymph nodes, its use in patients who have melanoma continues to be challenged. The future of SLN biopsy holds promise if prospective multicenter trials confirm a survival benefit for SLN biopsy as compared with watch-and-wait observation.

Prospective Multi-Institutional Study of Reverse Transcriptase Polymerase Chain Reaction for Molecular Staging of Melanoma

Purpose

To evaluate the prognostic significance of molecular staging using reverse transcriptase polymerase chain reaction (RT-PCR) in detecting occult melanoma cells in sentinel lymph nodes (SLNs) and circulating bloodstream.

Patients and Methods

In this multicenter study, eligibility criteria included patient age 18 to 71 years, invasive melanoma ≥ 1.0 mm Breslow thickness, and no clinical evidence of metastasis. SLN biopsy and wide excision of the primary tumor were performed. SLNs were examined by serial-section histopathology and S-100 immunohistochemistry. A portion of each SLN was frozen for RT-PCR. In addition, RT-PCR was performed on peripheral-blood mononuclear cells (PBMCs). RT-PCR analysis was performed using four markers: tyrosinase, MART1, MAGE3, and GP-100. Disease-free survival (DFS), distant–DFS (DDFS), and overall survival (OS) were analyzed.

Results

A total of 1,446 patients with histologically negative SLNs underwent RT-PCR analysis. At a median follow-up of 30 months, there was no difference in DFS, DDFS, or OS between the RT-PCR–positive (n = 620) and RT-PCR–negative (n = 826) patients. Analysis of PBMC from 820 patients revealed significant differences in DFS and DDFS, but not OS, for patients with detection of more than one RT-PCR marker in peripheral blood.

Conclusion

In this large, prospective, multi-institutional study, RT-PCR analysis on SLNs and PBMCs provides no additional prognostic information beyond standard histopathologic analysis of SLNs. Detection of more than one marker in PBMC is associated with a worse prognosis. RT-PCR remains investigational and should not be used to direct adjuvant therapy at this time.

Analysis of candidate genes through a proteomics-based approach in primary cell lines from malignant melanomas and their metastases

Proteomics provides a powerful approach for screening alterations in protein expression and post-translational modification associated with particular human diseases. In this study, the analysis of protein expression was focused on malignant melanoma in order to determine the candidate genes involved in tumour progression. The proteomes of cultured melanocytes and of cell lines from primary and metastatic lesions of one malignant melanoma patient were profiled using two-dimensional electrophoresis (2-DE) and mass spectrometry. Differentially expressed proteins were confirmed by 2-DE and mass spectrometry on an additional four malignant melanoma cell lines. Total RNA from the first subset of cell lines was used for quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) of the candidate genes identified after proteomics analysis. A very high similarity was observed in the 2-DE maps of two malignant melanoma cell lines derived from primary and secondary lesions of the same patient. Mass spectrometry identified 37 proteins which were found to be more abundant in tumour cells in comparison with control melanocytes (as confirmed on additional cell lines), with a relatively high prevalence of stress proteins. Eight candidate genes (PRDX2, HSP27, HSP60, HSPA8, HSP9B, STIP1, PDI and P4HB) were further characterized by evaluating their messenger RNA expression levels through real-time RT-PCR analysis. Overexpression of HSP27, HSP60 and HSPA8 and downregulation of PRDX2 were observed in cells from metastatic malignant melanoma in comparison with those from primary melanoma. Although further investigations with larger numbers of paired normal and tumour samples are needed, our findings strongly suggest that the dysregulation of stress pathways may be involved in melanoma progression.

Cutaneous melanoma: therapeutic lymph node and elective lymph node dissections, lymphatic mapping, and sentinel lymph node biopsy

Early clinical observation in cancer patients suggested that tumors spread in a methodical, stepwise fashion from the primary site, to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers, at least temporarily preventing the widespread dissemination of tumor. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics in cancer patients for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection, and most recently lymphatic mapping and sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall patient survival for cancer of any type, including melanoma, after surgical excision of regional lymphatics. This article will review the biology of lymphatics as it relates to regional tumor metastasis, and based on available information, offer practical recommendations for the clinical dermatologist and their patients who have cutaneous melanoma.

Pathologic assessment of melanoma sentinel nodes: a role for molecular analysis using quantitative real-time reverse transcription-PCR for MART-1 and tyrosinase messenger RNA

PURPOSE

Molecular analysis of melanoma sentinel nodes (SN) is sensitive, but poorly specific because metastases cannot be distinguished from benign nevus inclusions (BNI). We investigated whether quantitative reverse transcription-PCR (RT-PCR) detection of MART-1 and tyrosinase mRNAs could improve this specificity and contribute to SN assessment.

EXPERIMENTAL DESIGN

Two hundred twenty SNs from 95 melanoma patients analyzed by extensive immunohistopathology and real-time quantitative RT-PCR.

RESULTS

Using histopathology, SNs and patients were allotted to three diagnostic groups: (a) metastasis positive, (b) BNI positive, and (c) melanocyte-free. Median MART-1 and tyrosinase mRNA levels in SNs were significantly different in patients with metastasis compared with patients with BNIs (P < 0.05) and patients without melanocytic lesions (P < 0.001). However, a "gray-zone" was observed where distinction, based on mRNA levels, could not be made between the three groups. For both genes, the highest mRNA level recorded in each RT-PCR-positive patient was positively correlated with Breslow's tumor thickness. For SNs with metastases, tumor burden was significantly correlated to the mRNA level. Using the presence of a MART-1 RT-PCR signal to detect patients with metastases, a sensitivity of 100% and a negative predictive value of 100% were achieved when extensive immunohistology was used as reference.

CONCLUSIONS

Quantitative RT-PCR MART-1 and tyrosinase mRNA analysis cannot be used alone for SN diagnosis because of its poor specificity for melanoma metastasis. However, in approximately one third of cases without RT-PCR evidence of MART-1 expression, extensive histopathologic SN investigation is not necessary, thus substantially reducing the cost of SN analysis. The level of melanocyte-associated mRNA is associated with both tumor thickness and tumor burden as measured histopathologically, suggesting that this may be of prognostic value.

Detection of disseminated lung cancer cells in regional lymph nodes by assay of CK19 reverse transcriptase polymerase chain reaction and its clinical significance

PURPOSE

To set up a molecular method (i.e. RT-PCR) that can be used to detect disseminated tumor cells (DTCs) in regional lymph nodes (LNs) in patients with lung cancer and to evaluate its clinical significance.

METHODS

Cytokeratin 19 (CK(19)) was used as marker. Serial dilution study for LC-5 cells (a lung squamous cell line) was performed to detect sensitivity of the molecular protocol. Regional LNs (n = 261) and primary lung cancer tissue (n = 40) were obtained from 40 patients with lung cancer who underwent lobectomy or pneumonectomy. They were randomly categorized into two groups: group I (LN-based study, n = 20) and group II (patient-based study, n = 20). Each LN was halved. One half of a LN was subjected to histological examination (HE) and the other half was subjected to RT-PCR amplification of CK(19) mRNA. The effect on survival was analyzed. The cumulative survival was calculated by the Kaplan-Meier method and compared by the log rank test. The Cox model analyzed the prognostic factors.

RESULTS

CK(19) mRNA expressed in all tumor tissues as well as LC-5, PAa cells (a lung adenocarcinoma cell line), but not in normal control LNs. Serial dilution study for LC-5 cells demonstrated that CK(19) mRNA was detectable at a concentration as low as 10 LC-5 cells in 1x10(7) LN cells. There was no significant difference between the detecting result of single LN and that of mixed LNs (P > 0.05). In 18 of 40 patients, the metastasis in regional LNs was found by both HE and RT-PCR. Of 22 patients without pathologically involved nodes, six (27%) were found to express CK(19) mRNA in regional LNs. According to the results of regional LNs in 40 patients by molecular assay, the presence of the CK(19) product in LNs was related to tumor size (chi(2) = 5.76, P < 0.025) as well as cell differentiation of the tumor (chi(2) = 7.08, P < 0.01). Following a median observation time of 26 months (range, 4 to 60 months), patients with DTCs in nodes showed significant shorter disease-free survival duration than node-negative patients (log-rank test, P = 0.001). The independence of this prognostic significance was demonstrated by a multivariate analysis (Cox regression model, P = 0.004). The results diagnosed by HE had no significant effect on prognoses (P = 0.455).

CONCLUSIONS

Comparing with HE, RT-PCR can make more accurate assessment of metastatic status in LNs, which is helpful for screening the patients in whom the early subclinical metastasis exists and disclosing the intrinsic regulation of malignant metastasis. The presence of DTCs in LNs is an independent factor for prognosis. Molecular detection of DTCs in LNs is a supplement for current tumor staging in lung carcinoma.

Adjuvant treatment of malignant melanoma: where are we?

To date, no standard adjuvant therapy have increased overall survival in patients with malignant melanoma (MM). The effect of interferon alpha as a single agent or in combination has been widely explored in clinical trials. Critical reading of the major international randomised trials showed that response to interferon (IFN) in terms of improvement of overall survival (OS) may not be strictly correlated with the used dosage and that duration of therapy may impact disease-free survival (DFS) but not OS. Patients' heterogeneity could be an explanation for the discordant data of the international literature. Indeed, majority of these studies started in late 1980s or early 1990s, when accurate staging procedure were not available yet. The adequate surgical treatment should be considered as an independent variable in the analysis of MM adjuvant protocols. Considering the treatment cost, which is the main goal: DFS, OS or quality of life? Answering these questions is difficult, but some considerations must be taken to put order in this field. Putting together data from all different studies, IFN therapy seems to protect MM patients from recurrences during the entire treatment period and a prolonged IFN therapy seems to improve DFS. The only positive result on OS was demonstrated for high-dose IFN (HD-IFN) in a single study (presenting a relatively short follow-up median) and not confirmed in a subsequent study from the same authors. Considering that low-dose interferon (LD-IFN) is tolerated much better than HD-IFN (about 10% versus more than 70% of cases with grade 3-4 toxicity, respectively), a prolonged LD-IFN (more than 2 years) may represent a reasonable opportunity for MM patients, also considering its advantageous cost-effectiveness. Conversely, considering the improvement of OS as the main target of MM adjuvant therapy, the "wait and watch" attitude remains the only approach to be pursued at present. It is a physician's choice.

Technology for automated, rapid, and quantitative PCR or reverse transcription-PCR clinical testing

BACKGROUND

PCR-based assays can improve clinical care, but they remain technically demanding and labor-intensive. We describe a new instrument, the GeneXpert, that performs automated nucleic acid isolation, reverse transcription, and fluorescence-based quantitative PCR in approximately 35 min.

METHODS

Yield and integrity of RNA isolated on the GeneXpert were compared with Qiagen-based extraction for parallel samples (5-microm frozen tissue sections). The reproducibility of automated RNA isolation, reverse transcription, and quantitative PCR was determined by replicate (n = 10) analysis of 10 tissues, using duplex (target and endogenous control) reverse transcription-PCR reactions for two gene combinations. The GeneXpert was then used to perform rapid analysis of lymph nodes from melanoma, breast cancer, and lung cancer patients and analysis of melanoma metastatic to the lung, primary lung adenocarcinoma, and healthy lung tissue.

RESULTS

On the GeneXpert, RNA was recovered in slightly over 6 min, and the yield was approximately 70% of that from parallel Qiagen reactions. The RNA integrity was comparable to that of Qiagen-isolated RNA as determined by gel electrophoresis. For the melanoma samples, the 95% prediction interval for the deltaCt for a new measurement was +/-1.54 cycles, and for breast cancer samples, the interval for a newly observed deltaCt was +/-1.40 cycles. GeneXpert assays successfully detected the presence of metastatic melanoma, breast cancer, and lung cancer in lymph nodes and also differentiated among metastatic melanoma, lung adenocarcinoma, and healthy lung.

CONCLUSIONS

RNA yield and integrity on the GeneXpert are comparable to benchtop methods. Reproducibility of the GeneXpert data is similar to that seen with manual methods in our hands but may need improvement for some applications. The GeneXpert can perform RNA isolation, reverse transcription, and quantitative PCR in approximately 35 min and could therefore be used for intraoperative testing when applicable.

Characterization of micrometastatic disease in melanoma sentinel lymph nodes by enhanced pathology: recommendations for standardizing pathologic analysis

Lymphatic mapping and sentinel lymph node (SLN) biopsy are widely used as a staging technique for patients with cutaneous malignant melanoma who are at risk for metastases. SLN status has been shown to be a strong predictor of prognosis, and a variety of techniques have been used to identify minimal metastatic disease in SLNs. However, there is no validated consensus method for the optimal histologic analysis of SLNs harvested from melanoma patients. This study was conducted: 1) to assess the yield of metastatic melanoma detected in SLNs deemed negative by initial routine pathologic analysis (RPA) by subjecting them (after review of the original slides) to enhanced pathologic analysis (EPA) that included complete step-sectioning and immunohistochemistry (IHC); 2) to characterize the distribution of metastatic melanoma deposits within the SLNs; 3) to determine a preferred method of pathologic analysis applicable to daily practice; and 4) to attempt to assess the clinical significance of disease detected by EPA. A total of 105 SLNs were harvested from 49 patients who underwent successful SLN biopsy procedures during the period of study. Ten SLNs from 10 patients were positive on initial RPA and were not analyzed further. Ninety-five SLNs from the remaining 39 patients were reviewed and processed with additional hematoxylin and eosin, S-100 protein, and HMB-45 stains at 50-microm intervals for 20 levels or until the SLN tissue was exhausted. A single pathologist reviewed all sections without knowledge of the results of the other stains. Overall, metastatic melanoma was discovered in SLNs from 20 of the 39 patients: SLNs from 6 patients were found to have melanoma on review of the original hematoxylin and eosin slides, and SLNs from 14 patients were positive only after EPA. Twenty-one individual positive SLNs from these 14 patients were detected by EPA; of these, 10 positive SLNs were identified solely by IHC, representing 12% of the patient cohort and 10% of all SLNs studied by EPA. Detection rates were significantly associated with the staining method and the number of levels performed (P < 0.01). S-100 protein staining resulted in the highest yield of SLN positivity (86%), followed by HMB-45 (81%) and hematoxylin and eosin (52%). No single method detected all of the micrometastases. A detailed topographic mapping of metastatic deposits in SLNs was carried out. When using all three staining techniques, all 20 levels were required to identify 100% of the micrometastases; 95% of positive SLNs were identified with 17 levels, 90% with 15 levels, 75% with 10 levels, and 42% with 3 levels. Projected rates of detection for various different sectioning strategies were determined, with alteration of either the number of levels examined, the interval between the levels, or both. Detection of SLN positivity can be increased to 71% by performing three levels at 250-mum intervals, each level being composed of a set of three sections stained with hematoxylin and eosin, S-100 protein, and HMB-45, respectively. Therefore, this is the methodology we propose for the study of SLNs in melanoma patients. After a median follow-up of 87 months (range, 9-134 months), patients with EPA-detected disease and those with negative SLNs by EPA demonstrated improved recurrence-free and disease-specific survival compared with patients with RPA-detected disease in SLNs. Sampling error introduced by variations in pathologic processing should be addressed by standardization of pathologic methods, and the clinical significance of minimal SLN disease should be addressed in prospective studies of homogeneously staged patients.

Biomarkers for melanoma

PURPOSE OF REVIEW

Given the capricious nature of melanoma, biomarkers that provide significant insight into the behavior of melanoma would greatly aid in identifying patients at risk for disease progression, those whose disease has progressed subclinically, and those who would benefit from currently available systemic therapies. This review focuses on molecular prognostic markers in primary melanoma, markers that aid in the detection of metastatic melanoma, and markers predictive of systemic therapy.

RECENT FINDINGS

Significant advances have been made in the field of melanoma biomarkers. Utilization of paraffin-embedded tissue and multiple markers have improved the RT-PCR assays for detection of melanoma cells in lymph node tissue as well as peripheral blood. Lymphangiogenesis has been identified as a novel mechanism for melanoma progression, and candidate markers in the NF-kappaB signaling pathway have been identified to play a key role in melanoma: tumor vasculature interactions. Loss of heterozygosity has been used to identify potential candidates for biochemotherapy. Furthermore, serum S100B protein has been shown to be superior to lactate dehydrogenase in predicting prognosis and response to treatment for patients with advanced melanoma.

SUMMARY

Although recent studies have contributed greatly to the development of melanoma markers, it is anticipated that the application of gene expression profiling and proteomics techniques to melanocytic neoplasms will result in the identification of even more effective biomarkers for melanoma than those currently in clinical use.

Molecular markers in malignant cutaneous melanoma: Gift horse or one-trick pony?

The management of malignant cutaneous melanoma is problematic. Current clinical prognostic factors do not adequately predict disease recurrence and overall survival in a significant subset of patients. Adjuvant therapies for melanoma are notoriously toxic and associated with significant morbidity. Furthermore, it has been difficult to predict which patients will respond best to these treatments, if at all. DNA and RNA biomarkers have been developed to help overcome these problems. Biomarkers have been shown to upstage patients with melanoma, but are the assays sensitive and specific enough for clinical use as predictors of disease outcome or treatment response? We review our experience with DNA and RNA biomarkers in terms of their prognostic and predictive capabilities in malignant melanoma and outline their likely role in the future of melanoma staging, surveillance, and treatment.

New developments in the staging of melanoma

As the incidence of melanoma increases, so does the search for new staging techniques that may provide important prognostic information and aid in the detection of early metastatic disease. The application of molecular techniques may provide powerful new tools in this search. This review summarizes recent findings obtained by means of conventional RT-PCR, cDNA arrays, and proteomics in the investigation of human melanoma. The molecular tools discussed in this review demonstrate how global transcript and protein analysis might contribute not only to the staging of melanoma, but may hold great promise in improving the diagnosis and treatment of this disease.

Quantitative gene expression profiling in formalin-fixed, paraffin-embedded tissues using universal bead arrays

We recently developed a sensitive and flexible gene expression profiling system that is not dependent on an intact poly-A tail and showed that it could be used to analyze degraded RNA samples. We hypothesized that the DASL (cDNA-mediated annealing, selection, extension and ligation) assay might be suitable for the analysis of formalin-fixed, paraffin-embedded tissues, an important source of archival tissue material. We now show that, using the DASL assay system, highly reproducible tissue- and cancer-specific gene expression profiles can be obtained with as little as 50 ng of total RNA isolated from formalin-fixed tissues that had been stored from 1 to over 10 years. Further, tissue- and cancer-specific markers derived from previous genome-wide expression profiling studies of fresh-frozen samples were validated in the formalin-fixed samples. The DASL assay system should prove useful for high-throughput expression profiling of archived clinical samples.

Prognostic significance of detecting micrometastases by tyrosinase RT/PCR in sentinel lymph node biopsies: lessons from 322 consecutive melanoma patients

This prospective study was performed to determine the prognostic value of tyrosinase mRNA detection in sentinel lymph nodes (SLN) of melanoma patients. About 847 SLNs from 322 consecutive patients were assessed by histopathology and immunohistochemistry as well as tyrosinase-reverse transcriptase-polymerase chain reaction (RT/PCR) for the presence of micrometastases. The results were correlated with the prognostic parameters employing a multivariate analysis after a median follow-up of 37 months. Histopathological analysis revealed metastases in 34/322 patients (10.6%). Among the 288 patients with histopathologically negative SLN, tyrosinase-mRNA was detected in 39 patients. A relapse of the tumour occurred in 44.1% of the patients with histopathologically positive SLN, in 25.6% with histopathologically negative, but tyrosinase-RT/PCR-positive SLN, and 8.0% with "double-negative" SLN. A multivariate analysis identified tumour thickness, the histopathological SLN status, and the ulceration of the primary tumour as independent prognostic factors. Thus, by assessing tyrosinase mRNA in the SLN of melanoma patients, we identified a subgroup with histopathologically negative, but Tyr-RT-PCR-positive SLN who have a high risk of disease relapse.

Detection of melanoma cells in the lymphatic drainage after lymph node dissection in melanoma patients by using two-marker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The aim of this study was to evaluate the role of melanoma gene expression as a marker of the presence of melanoma cells in lymphatic drainage routinely collected after lymphadenectomy and to correlate reverse transcriptase-polymerase chain reaction (RT-PCR) assay results with recurrence, survival, and prognostic factors.

METHODS

We collected 24-hour postoperative lymphatic drainage samples (between days 2 and 4) from 93 patients with stage III melanoma who underwent radical lymphadenectomy between May 2002 and November 2003. We used RT-PCR assays with primers specific for the tyrosinase and MART-1 (Melan-A) genes. The samples were considered positive if at least one marker was expressed. Median follow-up time was 12.8 months.

RESULTS

In 18 (19.4%) of 93 patients, the RT-PCR assay results were positive: in 8 of 18 for tyrosinase only, in 7 of 18 for MART-1 only, and in 3 of 18 for both markers. We observed a significantly higher recurrence rate in patients with positive RT-PCR results (15 of 18; 83%) than negative results (26 of 75; 35%; P = .0001). Positive results of RT-PCR correlated with the number of involved lymph nodes (P = .0001) and extracapsular extension of nodal metastases (P = .03). We observed significant differences in overall and disease-free survival for RT-PCR-positive and -negative patients in univariate and multivariate analyses.

CONCLUSIONS

We observed positive RT-PCR assay results for melanoma cells in the lymphatic drainages of approximately 20% of patients after lymphadenectomy. This correlated significantly with early recurrence and shorter survival. These results may suggest that the RT-PCR assay could be useful for routinely analyzing postoperatively collected lymphatic drainage in stage III melanoma patients and for predicting disease progression.

Prognostic significance of molecular upstaging of paraffin-embedded sentinel lymph nodes in melanoma patients

PURPOSE

Detection of micrometastases in sentinel lymph nodes (SLNs) is important for accurate staging and prognosis in melanoma patients. However, a significant number of patients with histopathology-negative SLNs subsequently develop recurrent disease. We hypothesized that a quantitative realtime reverse transcriptase polymerase chain reaction (qRT) assay using multiple specific mRNA markers could detect occult metastasis in paraffin-embedded (PE) SLNs to upstage and predict disease outcome.

PATIENTS AND METHODS

qRT was performed on retrospectively collected PE SLNs from 215 clinically node-negative patients who underwent lymphatic mapping and sentinel lymphadenectomy for melanoma and were followed up for at least 8 years. PE SLNs (n = 308) from these patients were sectioned and assessed by qRT for mRNA of four melanoma-associated genes: MART-1 (antigen recognized by T cells-1), MAGE-A3 (melanoma antigen gene-A3 family), GalNAc-T (beta1-->4-N-acetylgalactosaminyl-transferase), and Pax3 (paired-box homeotic gene transcription factor 3).

RESULTS

Fifty-three (25%) patients had histopathology-positive SLNs by hemotoxylin and eosin and/or immunohistochemistry. Of the 162 patients with histopathology-negative SLNs, 48 (30%) had nodes that expressed at least one of the four qRT markers, and these 48 patients also had a significantly increased risk of disease recurrence by a Cox proportional hazards model analysis (P <.0001; risk ratio, 7.48; 95% CI, 3.70 to 15.15). The presence of > or = one marker in histopathology-negative SLNs was also a significant independent prognostic factor by multivariate analysis for overall survival (P =.0002; risk ratio, 11.42; 95% CI, 3.17 to 41.1).

CONCLUSION

Molecular upstaging of PE histopathology-negative SLNs by multiple-marker qRT assay is a significant independent prognostic factor for long-term disease recurrence and overall survival of patients with early-stage melanoma.

Standard immunostains for melanoma in sentinel lymph node specimens: which ones are most useful?

BACKGROUND

Sentinel lymph node (SLN) biopsy in melanoma is an increasingly used procedure. Pathologic evaluation of SLNs using immunohistochemistry improves diagnostic accuracy, yet no universally accepted standard protocol for pathologic processing of SLNs exists.

OBJECTIVE

The primary purpose of this study was to evaluate our experience with the sensitivity of the immunostains S-100, HMB-45, and Melan-A for SLN biopsy.

METHODS

Ninety-nine positive SLNs from 72 patients were retrospectively reviewed for the presence of microscopic metastatic melanoma on hematoxylin and eosin (H&E), S-100, HMB-45, and Melan-A stained sections and sensitivities of each immunohistochemical stain were determined.

RESULTS

The sensitivities of S-100, HMB-45, and Melan-A were 97%, 75%, and 96% respectively.

CONCLUSION

Given the lower sensitivity of HMB-45, our practice for evaluation of SLN biopsy specimens was modified using combinations of H&E, S-100, and Melan-A without HMB-45. If the H&E sections are negative or equivocal for metastatic melanoma, immunohistochemistry staining with S-100 protein and Melan-A is performed. New and improved protocols will undoubtedly be forthcoming as the field advances.

Identification of a novel candidate gene,CASC2, in a region of common allelic loss at chromosome 10q26 in human endometrial cancer

Allelic deletions, which are suggestive for the presence of tumor suppressor genes, represent a common event in endometrial cancer (EC). Previous loss-of-heterozygosity studies for human chromosome 10q identified a candidate deletion interval at 10q25-q26, which we further narrowed to a 160-kb region at 10q26, bounded by markers D10S1236 and WIAF3299. Using a positional candidate approach, we identified three alternative transcripts of a novel human gene, CASC2 (cancer susceptibility candidate 2; formely C10orf5). One of such transcripts, CASC2a, encodes a short protein of 102 amino acids with no similarity to any other known gene product. Three (7%) CASC2a mutations were identified in tumor DNA from 44 EC patients. While c.-156G>T and c.22C>T (p.Pro8Ser) are sequence variants with unknown functional significance, c.84delA is a mutation with a truncation effect on the predicted protein (p. Asn28fsX50). Expression studies by real-time RT-PCR on several normal and tumor cells revealed that CASC2a mRNA is downregulated in cancer, suggesting that it may act as a potential tumor suppressor gene. The very low mutation rate seems to also indicate that inactivation of CASC2a might probably be due to mechanisms different from genetic alterations.

Additional reverse transcription-polymerase chain reaction of peripheral slices is not superior to analysis of the central slice in sentinel lymph nodes from melanoma patients

BACKGROUND

The status of the sentinel lymph node (SLN) is an important prognostic factor in patients with cutaneous melanoma. Reverse transcription-polymerase chain reaction (RT-PCR) has been used as a sensitive means of detecting tumour cells in SLNs.

OBJECTIVES

To determine whether RT-PCR analysis of the SLN using both the central and the peripheral slices is more sensitive than molecular analysis of the central slice only.

METHODS

Eighty-three SLNs from 59 patients with primary cutaneous melanoma were identified by SLN mapping. All SLNs were bisected along their longitudinal axis to produce two equal halves. One half was used for histology and immunohistochemistry, and the other was analysed by RT-PCR for tyrosinase and MelanA. Parallel to the longitudinal axis, one central slice (approximately 2 mm in thickness) was cut manually. This central slice was used for our standard RT-PCR protocol. In the current study, up to eight additional peripheral slices (each approximately 2 mm in thickness) were cut parallel to the existing cut surface. These peripheral slices were analysed by additional RT-PCR.

RESULTS

Standard RT-PCR of the central slice yielded positive results in 34 of 59 patients (57%). Additional RT-PCR of peripheral slices demonstrated positive findings in six additional patients (10%) who were initially negative by standard RT-PCR of the central slice. In detail, seven of those 34 patients positive by standard RT-PCR of the central slice had positive histological findings. In each of these seven patients, RT-PCR was positive both in the central slice as well as in the peripheral slices. The remaining 27 patients with positive RT-PCR results of the central slice showed negative histological findings. Only nine (33%) of these 27 patients had a positive RT-PCR also in the peripheral slices. Finally, all 25 patients with negative RT-PCR results in the central slice showed negative histological findings. Six of these patients (24%) revealed positive RT-PCR results on the analysis of peripheral slices. However, three of these patients expressed only MelanA but not tyrosinase. Thirty lymph nodes from 24 nonmelanoma patients served as negative controls for RT-PCR. In three of these 24 patients (13%) expression of MelanA but not tyrosinase was detected by RT-PCR.

CONCLUSIONS

Molecular analysis of peripheral slices yielded six additional patients (10%) positive by RT-PCR who were initially negative by standard RT-PCR of the central slice. However, three of these six patients were found to express only MelanA but not tyrosinase. As MelanA expression was also found in 13% of control lymph nodes, positive MelanA expression alone in SLNs of melanoma patients requires cautious interpretation in order to avoid false-positive findings. Thus, additional molecular processing of peripheral slices did not significantly increase the number of patients with RT-PCR-positive SLNs.

Detection of micrometastases in sentinel lymph nodes from melanoma patients

The technique of sentinel lymph node (SLN) dissection is a reliable predictor of metastatic disease in the lymphatic basin draining the primary melanoma. Reverse transcription-polymerase chain reaction (RT-PCR) is emerging as a highly sensitive technique to detect micrometastases in SLNs, but its specificity has been questioned. A prospective SLN study in melanoma patients was undertaken to compare in detail immunopathological versus molecular detection methods. Sentinel lymphadenectomy was performed on 57 patients, with a total of 71 SLNs analysed. SLNs were cut in slices, which were alternatively subjected to parallel multimarker analysis by microscopy (haematoxylin and eosin and immunohistochemistry for HMB-45, S100, tyrosinase and Melan-A/MART-1) and RT-PCR (for tyrosinase and Melan-A/MART-1). Metastases were detected by both methods in 23% of the SLNs (28% of the patients). The combined use of Melan-A/MART-1 and tyrosinase amplification increased the sensitivity of PCR detection of microscopically proven micrometastases. Of the 55 immunopathologically negative SLNs, 25 were found to be positive on RT-PCR. Notably, eight of these SLNs contained naevi, all of which were positive for tyrosinase and/or Melan-A/MART-1, as detected at both mRNA and protein level. The remaining 41% of the SLNs were negative on both immunohistochemistry and RT-PCR. Analysis of a series of adjacent non-SLNs by RT-PCR confirmed the concept of orderly progression of metastasis. Clinical follow-up showed disease recurrence in 12% of the RT-PCR-positive immunopathology-negative SLNs, indicating that even an extensive immunohistochemical analysis may underestimate the presence of micrometastases. However, molecular analyses, albeit more sensitive, need to be further improved in order to attain acceptable specificity before they can be applied diagnostically.

Sentinel Lymph Node Biopsy Has No Benefit for Patients with Primary Cutaneous Melanoma Metastatic to a Lymph Node: An Assertion Based on Comprehensive, Critical Analysis

The thesis is set forth in this treatise that there is no place in the routine practice of medicine for the procedure for melanoma known conventionally and universally as sentinel node biopsy. Our assertion is based on assessment of the extensive body of literature devoted to the subject of treatment of melanoma before any metastasis has manifested itself clinically and of that dedicated to therapy for overt metastatic melanoma by a variety of modalities, chief among those addressed here being elective lymph node dissection and sentinel lymph node biopsy. In this era of sentinel lymph node biopsy, elective lymph node dissection has been modified to include only patients with metastasis of melanoma to lymph nodes, a procedure now termed "selective complete lymph node dissection." Among adjuvant medical therapies, the most popular today is interferon alpha-2B. Critical, incisive scrutiny of the literature leads to the conclusion, incontrovertibly, that elective lymph node dissection has no benefit for a patient and that all modifications of it also are devoid of value. The reason, logically, for the lack of utility of elective lymph node dissection becomes apparent by virtue of the route taken by cells of melanoma as they metastasize; those cells proceed in the same fashion as does lymph, bacteria, foreign material (including vital dyes and radioactive tracers), and other kinds of cells, to wit, by passing rapidly through nodes, including the sentinel one, and even bypassing entirely the nodes. In reality, cells of metastatic melanoma are not held up in nodes for any significant period of time, contrary to what is asserted repeatedly, but without any basis in fact, by many students of the subject. Moreover, not a single adjuvant medical therapy available currently is effective against metastatic melanoma and, therefore, none of them should be invoked to justify performance of sentinel node biopsy. Even if the sentinel node is found to house cells of melanoma, which, as a rule, conveys a grim message regarding the future, the finding in an individual patient is meaningless; a particular patient may live in harmony with metastases of melanoma for more than 30 years and even die of an unrelated malady. In short, no surgeon, pathologist, or oncologist is a seer, diviner, or prophet when it comes to predicting accurately the outcome for a patient with metastasis of melanoma; the end could come in weeks, months, or decades. If, however, a sentinel node is found to contain nary a cell of metastatic melanoma, it, too, means nothing for an individual patient because the existence of metastases widely is not excluded by that finding. In short, sentinel node biopsy cannot be considered the standard of care in the daily practice of medicine; it is woefully substandard because it is without benefit. There is no justification, whatsoever, for the procedure, scientifically or practically, and for that reason it should be abandoned, without delay, now.

The risk of regional lymph node metastases in patients with melanoma less than 1.0 mm thick: recommendations for sentinel lymph node biopsy

BACKGROUND

Lymphatic mapping and sentinel lymph node biopsy can upstage patients with intermediate thickness (1.0 to 4.0 mm) melanoma. Currently, there are no strict guidelines for sentinel lymph node biopsy in patients with melanoma <1.0 mm thick.

STUDY DESIGN

A retrospective review of our patient database (598 patients treated at two institutions in Baltimore, MD, between January 1970 and June 2002) was performed to identify patients with primary cutaneous melanoma <1.0 mm thick who developed recurrent disease. This cohort of patients with > or =5 years of followup from the date of diagnosis was compared with patients with primary melanoma of similar thickness and similar followup intervals without recurrent disease.

RESULTS

A total of 114 patients with primary cutaneous melanoma <1.0 mm thick were identified, 17 of whom developed disease recurrence. In 13 patients, the site of first recurrence was the regional lymph nodes and in 4 patients disease recurred with distant metastases. The median time to lymph node recurrence was 55 months (range 2 to 112) months. Patients with regional lymph node recurrences had a significant (p = 0.02) difference in median primary tumor thickness of 0.80 mm versus 0.45 mm in patients without recurrent disease; there was no association of Clark level of invasion to recurrence (p = 0.42). In all, 35% of patients (7 of 20) presenting with melanoma 0.80 to 0.99 mm thick developed lymph node recurrence a median of 41 months (range 8 to 112 months) after surgical treatment.

CONCLUSIONS

Sentinel lymph node biopsy can be justified for patients with melanoma > or =0.8 mm thick provided that the technique would detect metastatic disease years before it becomes clinically evident.

Tyrosinase RT-PCR as a Supplement to Histology for Detecting Melanoma and Nevus Cells in Paraffin Sections of Sentinel Lymph Nodes

The detection of tyrosinase mRNA in sentinel lymph nodes (SLNs) by reverse transcription polymerase chain reaction (RT-PCR) is a sensitive indicator for the presence of melanoma or nevus cells, but it does not enable a distinction between both. We have established an efficient method for extraction and reverse transcription of tyrosinase mRNA from paraffin sections that permits the close correlation of the RT-PCR results with (immuno)histologic findings in adjacent sections. One hundred fifty-three SLNs and 6 non-SLN specimens originating from 92 melanoma and 4 nonmelanoma patients were studied to test the reliability of this approach. The predictive value of positive RT-PCR results was 0.98 for the presence of melanoma or nevus cells; the corresponding negative predictive value was 0.83. Furthermore, the detection rate of tyrosinase mRNA significantly correlated with tumor burden. Among the 33 melanoma-positive SLNs without nevus cells, positive RT-PCR results were obtained in all specimens with extended peripheral (S2) or deeply invasive (S3) micrometastases but in only 46% of the cases with few localized melanoma cells in the subcapsular zone (S1). Routine (immuno)histologic evaluation alone had missed microclusters of melanoma cells in one SLN and small nevus cell aggregates in six other SLNs. They were detected only during microscopic reexamination caused by a positive RT-PCR result. We conclude that histology and immunohistochemistry remain the indispensable gold standard for the identification of melanoma and nevus cells in SLNs. Additional molecular analyses using adjacent paraffin sections may further improve the diagnostic accuracy by sensitizing and guiding the microscopist's attention.

Prognostic value of circulating melanoma cells detected by reverse transcriptase-polymerase chain reaction

PURPOSE

Factors that are predictive of prognosis in patients who are diagnosed with malignant melanoma (MM) are widely awaited. Detection of circulating melanoma cells (CMCs) by reverse transcriptase-polymerase chain reaction (RT-PCR) has recently been postulated as a possible negative prognostic factor. Two main questions were addressed: first, whether the presence of CMCs, defined as the patient being positive for any of the three markers, had a prognostic role; and second, what the predictive value of each individual marker was.

PATIENTS AND METHODS

A consecutive series of 200 melanoma patients observed between January 1997 and December 1997, with stage of disease ranging from I to IV, was analyzed by semiquantitative RT-PCR. Tyrosinase, p97, and MelanA/MART1 were used as markers to CMCs on baseline peripheral blood samples. Progression-free survival (PFS) was used as a unique end point and was described by the product limit method. Multivariable analysis was applied to verify whether the auspicated prognostic value of these markers was independent of the stage of disease, and a subgroup analysis was performed that excluded patients with stage IV disease.

RESULTS

Overall, 32% (64 of 200) of patients progressed, and a median PFS of 52 months in the whole series was observed. The presence of CMCs and the markers individually or combined was predictive of prognosis in the univariate analysis but did not provide additional prognostic information to the stage of disease in multivariable models. In the subgroup analysis of stage (ie, I-III subgroup), similar results were observed.

CONCLUSION

Detection of CMCs in peripheral blood samples at the time of MM diagnosis by semiquantitative RT-PCR does not add any significant predictive value to the stage of disease. Thus, this approach should not be used in clinical practice, and further studies are required to determine its usefulness.

Specificity of tyrosinase and HMB45 PCR in the detection of melanoma metastases in sentinel lymph node biopsies

AIMS

Sentinel lymph node biopsy is an increasingly established procedure in the primary staging of high-risk melanoma patients. However, the laboratory evaluation of sentinel lymph node biopsies is a matter of controversy. The aim of this study was to determine the specificity of polymerase chain reaction (PCR) techniques for the evaluation of lymph nodes with regard to melanoma metastases in comparison with histology and immunohistology.

METHODS AND RESULTS

Sentinel lymph nodes (n = 41) from 29 melanoma patients and 29 lymph nodes from 27 patients without melanoma were analysed by histology (H&E) and immunohistology (Melan A, HMB45). cDNA of these lymph nodes was subjected to LightCycler PCR amplification using primers specific for tyrosinase and HMB45. Two melanoma sentinel lymph nodes contained naevus cells by histology and immunohistology and were therefore excluded from further evaluation. Eight (20.5%) of the remaining 39 melanoma sentinel lymph nodes were positive by histology and immunohistology and tyrosinase PCR, 15.4% (6/39) were positive only by tyrosinase PCR, 2.6% (1/39) were positive only by histology and immunohistology. HMB45 PCR revealed positive results in 7.7% (3/39) sentinel lymph nodes, which were also positive by tyrosinase PCR and histology and immunohistology. Of non-melanoma lymph nodes 13.8% (4/29) and 14.8% (4/27) of non-melanoma patients were positive by tyrosinase PCR but negative by histology and immunohistology and HMB45 PCR. Thus, tyrosinase PCR had a specificity of only 85.2%.

CONCLUSIONS

The specificity of tyrosinase PCR and the sensitivity of HMB45 PCR are too low to recommend these PCR examinations for the guidance of therapy, in particular complete regional lymph node dissection.

New diagnostic techniques in staging in the surgical treatment of cutaneous malignant melanoma

The emphasis of the research on the surgical treatment of melanoma has been on the resection margins, the role of elective lymph node dissection in high risk patients and the value of adjuvant regional treatment with hyperthermic isolated lymph perfusion with melphalan. Parallel to this research, new diagnostic techniques, such as Positron Emission Tomography and the introduction of the sentinel lymph node biopsy with advanced laboratory methods such as immuno-histochemical markers, and reverse transcriptase polymerase chain reaction, have been developed to facilitate early detection of metastatic melanoma. The role of these new techniques on the staging and surgical treatment of melanoma is discussed in this paper.

Pathological and molecular assessment of sentinel lymph nodes in solid tumors

Sentinel nodes (SNs) are the first set of nodes to receive drainage and cancer cells from a primary tumor. While there may be a single SN, frequently there are one to three or more SNs. The development of sentinel node surgery over the last decade has led to dramatic changes in the surgical approach to regional nodes draining solid tumors. The surgeon can now identify, to a level of accuracy previously impossible, the regional nodes most likely to be involved with cancer in any individual patient. This new capability comes at a cost; the principles guiding the extent of nodal surgery must be completely re-examined. The extent of surgical resection required to achieve each of the goals of regional node surgery-(1) establishing prognosis, (2) obtaining regional control, and (3) improving overall survival-may no longer be simply the default "regional node resection" and may vary depending on the clinical goals. Inseparable from this new surgical technology is the methodology employed for pathologic evaluation of SNs. It is critical that pathologists and clinicians conduct definitive clinical research directed toward defining the role and impact that SN surgery has on each of these surgical goals.

Lymphatic dissemination of tumour cells and the formation of micrometastases

Most human cancers show evidence of metastatic spread to regional lymph nodes, and the extent of lymph-node involvement is directly related to dinical outcome. Increased expression of vascular endothelial growth factor C in primary tumours is associated with increased dissemination of tumour cells to regional lymph nodes in various human carcinomas. Arguments favouring the activation of pre-existing lymphatic endothelium and the de novo formation of lymphatic capillaries (lymphangiogenesis) are discussed. We highlight recent advances in the molecular detection and characterisation of lymph-node micrometastases, as well as potential microenvironmental factors, such as chemokines, which may influence the migration and growth of metastatic tumour cells. Finally, we examine the clinical significance of lymphatic-mediated tumour-cell dissemination and the formation of lymph-node micrometastases.

Surgical strategies and minimal residual disease detection

The ultimate goal in the treatment of cancer patients is the elimination of all tumor cells. A cure by surgery alone is possible only if the tumor is still confined locally. Detection of disseminated tumor cells may help to individually tailor the surgical procedure to each patient: extended or limited resections may be indicated depending on the individual state of tumor cell dissemination. In cases of systemic tumor cell dissemination, surgery alone cannot cure the patient. Thus, by detecting disseminated tumor cells, patients with a higher risk for relapse, who might benefit from multimodal therapeutic regimes, could be defined. A second aspect is the possibility of tumor cell shedding induced by manipulation during surgical procedures, which could be demonstrated for several tumor entities. Intraoperative tumor cell dissemination could be prevented by alternative operative strategies. In addition, perioperative antibody or cytotoxic therapy may prevent tumor cell implantation. Well-designed clinical studies are now of major importance to evaluate the clinical impact of individualized patient management and altered surgical procedures.

Pathologic analysis of sentinel lymph nodes

The sentinel lymph node (SLN) procedure enables selective targeting of the first draining lymph node, where the initial metastases will form. A negative SLN predicts the absence of tumor metastases in the other regional lymph nodes with a high degree of accuracy. This means that in case of a negative SLN, regional lymph node dissection is no longer necessary. Besides saving patients the significant morbidity associated with lymph node dissection, it will also save costs. Crucial for the success of the SLN procedure is the screening of the SLN for metastases by the pathologist. To this end, several techniques are available such as standard histo- and cytopathological techniques, immunohistochemistry, flow cytometry, and molecular biological techniques. In this paper, the value of these methods for detecting SLN metastases is discussed. Some of these techniques have also appeared to be quite useful for intraoperative evaluation of SLNs. The standard protocol for detection of SLN metastases consists of extensive histopathological investigation including stepped sections stained with hematoxylin and eosin (HE) and immunohistochemistry. Intraoperative frozen section analysis and imprint cytology of SLNs have been shown to be reasonably reliable for detecting breast cancer metastases in SLNs. Further studies are necessary to establish the role of multiparameter flow cytometry and sophisticated molecular biological techniques such as reverse transcription polymerase chain reaction (RT-PCR) in detecting SLN metastases.