Detection of Melanoma Cells in Sentinel Lymph Nodes by Reverse Transcriptase-Polymerase Chain Reaction: Prognostic Significance

Morbidity of Selective Lymph Node Biopsy for Melanoma: Meta-Analysis of Complications

Background and Aim

Intraoperative lymphatic mapping and selective lymph node biopsy is accepted worldwide as the standard procedure for staging regional lymph nodes of 1–4 mm thick melanomas, as well as for other neoplasms. Although it is often stated that selective lymph node biopsy is a minimally invasive procedure associated with few complications, few data exist concerning the morbidity associated with the procedure. The present analysis was performed to evaluate the morbidity associated with selective lymph node biopsy in a long-term follow-up.

Materials and Methods

The study provides a review of 437 selective lymph node biopsies on 269 patients, operated on between the 1994 and the 2009, for the lymph node biopsy of head and neck, groin, axilla, upper and lower limbs and nodal basins. Patients’ history and follow-up were reviewed for 2 weeks after surgery, every 3 months for the first 2 years, every 4 months during the third year, and every 6 months subsequently, and postoperative morbidity was evaluated.

Results

After sentinel node biopsy, 14 patients developed one of the following complications: hematoma, 1 case (0.30%); lymphedema, 1 case (0.30%); seroma, 2 cases (0.61%); wound infection, 6 cases (1.83%); keloid scar, 2 cases (0.61%); and postoperative pain, 2 cases (0.61%). The total complication rate was 4.26%.

Conclusions

Selective lymph node biopsy for melanoma, as for other tumors, in respect to radical lymphadenectomy, is not a complications-free procedure but is usually not severe.

Sentinel lymph nodes in cutaneous melanoma: handling, examination, and clinical repercussion

CONTEXT

Within the last 15 years, evaluation of sentinel lymph nodes (SLNs) has become the most popular method of early staging of several malignancies, including melanoma. Sentinel lymph nodes are usually examined on formalin-fixed, paraffin-embedded sections and by routine histology/immunohistochemistry (research protocols have used other techniques such as polymerase chain reaction). Approximately 20% of patients with cutaneous melanoma have metastasis in the SLN. In most studies, detection of positive SLN conveys a poorer prognosis for patients with cutaneous melanoma.

OBJECTIVE

To review the morphologic patterns of melanoma metastasis in the SLN, the differential diagnosis, and the quantification of tumor burden as a prognostic factor.

DATA SOURCES

Personal observations and review of the pertinent literature.

CONCLUSIONS

Evaluation of sentinel lymph nodes is certainly becoming a widespread technique and most authors agree on its prognostic power for staging patients with cutaneous melanoma. Current studies are evaluating the possible therapeutic value of removal of positive 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.

Sentinel Lymph Nodes in Cutaneous Melanoma

Examination of sentinel lymph nodes (SLN) has probably become the most popular method of early staging of patients who have cutaneous melanoma because SLN are considered to be the lymph nodes most likely to contain metastatic deposits; they can be examined in a more intense manner than in standard lymphadenectomy. There are several protocols to examine SLN but most of them use formalin-fixed, paraffin-embedded sections stained with hematoxylin and eosin with the addition of immunohistochemistry. By using these protocols, approximately 20% of patients who have cutaneous melanoma have melanoma cells in the SLN. Current studies are evaluating the possible therapeutic value of removal of positive SLN, but it is accepted by most authors that detection of positive SLN conveys an impaired prognosis for patients who have cutaneous melanoma.

Molecular staging of pathologically negative sentinel lymph nodes from melanoma patients using multimarker, quantitative real-time rt-PCR

The aim of this study was to evaluate the prognostic potential of quantitative reverse-transcription, polymerase chain reaction (qRT-PCR) in melanoma patients with pathologically negative sentinel lymph nodes (SLN). Our study included 195 node-negative melanoma patients with a Breslow thickness greater than 0.76 mm (n = 158), or less than 0.76 mm but who had Clark level IV-V, microscopic ulceration, or pathological signs of regression (n = 32), and five patients with melanoma of unknown thickness. SLNs were examined by serial-section histopathology. A portion of each SLN was frozen for qRT-PCR analysis using markers Tyrosinase, MART1, SSX2, MAGEA3, PAX3, and GalNAc-T. In addition, two other markers (PLAB and L1CAM) were evaluated for melanoma specificity but not for SLN analysis. Median follow-up was 64 months, during which time there were 15 (7.7%) recurrences. A total of 370 lymph nodes were analyzed by qRT-PCR. No association was found between quantitative expression level of any marker and disease recurrence. Previously published primer designs were tested for PAX3 and GalNAc-T and revealed that alternative PAX3 transcripts are differentially expressed in melanoma and benign lymph nodes. No associations with recurrence were found regardless of the transcripts amplified by different primer sets. PLAB and L1CAM did not appear to differentiate between malignant melanoma and benign melanocytes or lymph nodes in our analysis. We conclude that, in this large cohort of patients, multimarker qRT-PCR analysis of SLNs did not correlate with disease recurrence. Our data support specific PAX3 splice variants but not GalNAc-T, PLAB or L1CAM as possible markers for melanoma metastasis to 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.

Clinical significance of the RT-PCR positive sentinel node in melanoma

BACKGROUND

The clinical relevance of RT-PCR positivity for melanoma markers in the sentinel node remains controversial. Our purpose was to determine whether patients with a histologically negative but RT-PCR positive node were at an increased risk for recurrence than their RT-PCR negative counterparts.

METHODS

Thirty-nine adult patients underwent sentinel node biopsies for melanoma between 1998 and 2000. Each sentinel node was bivalved. Half was serially sectioned and examined by routine hematoxylin and eosin (H&E) and immunohistochemistry (IHC; S100, HMB-45, melanA, and tyrosinase). The other half was analyzed by a nested RT-PCR assay for tyrosinase.

RESULTS

Patients were followed for recurrence with a mean follow-up of 71.1 months. The odds ratio of recurrence for RT-PCR positive versus RT-PCR negative patients was 1.39 (0.34, 5.62; p = 0.73). Within the histology negative subgroups, the risk of recurrence in the RT-PCR positive group (26.7%) was not significantly different from the risk of recurrence in the RT-PCR negative group (22.2%) (p = 0.33 chi-squared). RT-PCR of the sentinel node was not a predictor for recurrence on multivariate analysis (p = 0.65).

CONCLUSION

Sentinel node RT-PCR positivity did not risk stratify histologically negative melanoma patients beyond routine pathologic examination in this series.

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.

Early-Stage Melanoma: Staging Criteria and Prognostic Modeling

Accurate risk assessment is central to the process of making rational surgical and systemic treatment recommendations for melanoma patients and in establishing appropriate clinical trial stratification criteria. The current American Joint Commission on Cancer melanoma staging system incorporated relevant prognostic variables to provide a framework for the estimation of risk for recurrence; however, significant prognostic heterogeneity exists within the stage groupings. In the stage I/II group, survival rates range from 40% to 95% as defined by the combination of tumor thickness and ulceration. The use of novel prognostic factors, such as mitotic rate, sentinel node biopsy, and prognostic modeling using a variety of factors, can minimize this prognostic heterogeneity and provide a more accurate and individualized prognostic profile. Recent modifications in the stage III criteria include the number of positive nodes, whether the nodal disease is microscopic or clinically apparent, and the presence of an ulcerated primary. Through these factors, survival estimates can be provided, but like the stage I/II group, wide ranges in prognosis exist. The complexion of the stage III population is in evolution as a result of increasing numbers of patients being diagnosed as having microscopic sentinel node disease. Contemporary efforts are focused on defining the prognosis and natural history of this group. Through prognostic modeling using the number of nodes involved, ulceration status, and a measure of disease burden--disease in the sentinel node--relatively homogeneous subgroups can be identified. Long-term follow-up of patients staged with PCR molecular techniques on sentinel nodes shows conflicting value in assessing prognosis and therefore cannot be routinely used outside a clinical trial. The combination of genomic profiling using microarray analyses and the development of targeted therapy holds the future promise of individualizing prognosis and therapy.

New American Joint Commission on Cancer Staging System for Melanoma: Prognostic Impact and Future Directions

Accurate melanoma staging is critical in establishing management strategies and estimating disease relapse. Combined with assessment of comorbidities and understanding treatment toxicities, risk assessment is central to offering appropriate surgical or systemic therapies. The American Joint Commission on Cancer (AJCC) melanoma staging system provides survival estimates within anatomically defined disease categories. Newer prognostic factors and methods of prognostic analyses can augment predictions for the presence of micro-metastatic disease and further define the risk for relapse. This article highlights relevant changes, evidence supporting future incorporation of more recently defined prognostic variables, novel approaches used as adjuncts to the current staging system, and future directions of the AJCC staging committee.

Sentinel lymph node biopsy in thin melanoma patients

BACKGROUND

We sought to determine the incidence of positive sentinel lymph nodes in thin melanoma (<or=1.0 mm) patients and if subgroups could be identified with a higher risk of occult nodal disease.

METHODS

Patients with <or=1.0 mm lesions treated between 1997 and 2003 were reviewed. Sentinel nodes underwent microscopic analysis including step sectioning and immunohistochemical examination. Some nodes underwent reverse transcriptase-polymerase chain reaction (RT-PCR) evaluation for melanoma markers.

RESULTS

Sixty-four of 107 thin melanoma patients underwent sentinel node biopsy (SNB). Mapped patients were more likely to have Clark >or= III and thicker lesions (mean 0.77 mm vs. 0.47 mm), but were not different in regards to age, sex, or lesion location. Eight percent and 58% of sentinel nodes were positive by routine histology and RT-PCR, respectively. Among mapped patients, younger age was the only significant prognostic factor for node positivity. With a median follow-up of 18 months among all patients, one regional recurrence (at 2 years) has been identified.

CONCLUSIONS

Given the low morbidity of sentinel lymph node biopsy, this procedure should be discussed with selected thin melanoma patients to detect microscopic disease, however PCR positivity by our methods is too commonly seen to be clinically significant in thin melanoma patients and requires additional study.