Stanley P. L. Leong

The gene expression signatures of melanoma progression

Because of the paucity of available tissue, little information has previously been available regarding the gene expression profiles of primary melanomas. To understand the molecular basis of melanoma progression, we compared the gene expression profiles of a series of nevi, primary melanomas, and melanoma metastases. We found that metastatic melanomas exhibit two dichotomous patterns of gene expression, which unexpectedly reflect gene expression differences already apparent in comparing laser-capture microdissected radial and vertical phases of a large primary melanoma. Unsupervised hierarchical clustering accurately separated nevi and primary melanomas. Multiclass significance analysis of microarrays comparing normal skin, nevi, primary melanomas, and the two types of metastatic melanoma identified 2,602 transcripts that significantly correlated with sample class. These results suggest that melanoma pathogenesis can be understood as a series of distinct molecular events. The gene expression signatures identified here provide the basis for developing new diagnostics and targeting therapies for patients with malignant melanoma.

Multivariate Analysis of Prognostic Factors Among 2,313 Patients With Stage III Melanoma: Comparison of Nodal Micrometastases Versus Macrometastases

PURPOSE To determine the survival rates and independent predictors of survival using a contemporary international cohort of patients with stage III melanoma. PATIENTS AND METHODS Complete clinicopathologic and follow-up data were available for 2,313 patients with stage III disease in an updated and expanded American Joint Committee on Cancer (AJCC) melanoma staging database. Kaplan-Meier and Cox multivariate survival analyses were performed. RESULTS Among all 2,313 patients with stage III disease, 81% had micrometastases, and 19% had clinically detectable macrometastases. The 5-year overall survival was 63%; it was 67% for patients with nodal micrometastases, and it was 43% for those with nodal macrometastases (P < .001). Tremendous heterogeneity in survival was observed, particularly in the microscopically detected nodal metastasis subset (from 23% to 87% for 5-year survival). Multivariate analysis demonstrated that in patients with nodal micrometastases, number of tumor-containing lymph nodes, primary tumor thickness, patient age, ulceration, and anatomic site of the primary independently predicted survival (all P < .01). When added to the model, primary tumor mitotic rate was the second-most powerful predictor of survival after the number of tumor-containing nodes. In contrast, for patients with nodal macrometastases, the number of tumor-containing nodes, primary ulceration, and patient age independently predicted survival (P < .01). CONCLUSION In this multi-institutional analysis, we demonstrated remarkable heterogeneity of prognosis among patients with stage III melanoma, especially among those with nodal micrometastases. These results should be incorporated into the design and interpretation of future clinical trials involving patients with stage III melanoma.

Prognostic Significance of Mitotic Rate in Localized Primary Cutaneous Melanoma: An Analysis of Patients in the Multi-Institutional American Joint Committee on Cancer Melanoma Staging Database

PURPOSE The aim of this study was to assess the independent prognostic value of primary tumor mitotic rate compared with other clinical and pathologic features of stages I and II melanoma. METHODS From the American Joint Committee on Cancer (AJCC) melanoma staging database, information was extracted for 13,296 patients with stages I and II disease who had mitotic rate data available. RESULTS Survival times declined as mitotic rate increased. Ten-year survival ranged from 93% for patients whose tumors had 0 mitosis/mm(2) to 48% for those with ≥ 20/mm(2) (P < .001). Mean number of mitoses/mm(2) increased as the primary melanomas became thicker (1.0 for melanomas ≤ 1 mm, 3.5 for 1.01 to 2.0 mm, 7.3 for 3.01 to 4.0 mm, and 9.6 for > 8 mm). Ulceration was also associated with a higher mitotic rate; 59% of ulcerated melanomas had ≥ 5 mitoses/mm(2) compared with 16% of nonulcerated melanomas (P < .001). In a multivariate analysis of 10,233 patients, the independent predictive factors for survival in order of statistical significance were as follows: tumor thickness (χ(2) = 104.9; P < .001), mitotic rate (χ(2) = 67.0; P < .001), patient age (χ(2) = 48.2; P < .001), ulceration (χ(2) = 46.4; P < .001), anatomic site (χ(2) = 34.6; P < .001), and patient sex (χ(2) = 33.9; P < .001). Clark level of invasion was not an independent predictor of survival (χ(2) = 3.2; P = .37). CONCLUSION A high mitotic rate in a primary melanoma is associated with a lower survival probability. Among the independent predictors of melanoma-specific survival, mitotic rate was the strongest prognostic factor after tumor thickness.

Adverse Reactions to Isosulfan Blue During Selective Sentinel Lymph Node Dissection in Melanoma

Background: Selective sentinel lymph node (SLN) dissection can spare about 80% of patients with primary melanoma from radical lymph node dissection. This procedure identifies the SLN either visually by injecting isosulfan blue dye around the primary melanoma site or by handheld gamma probe after radiocolloid injection.Methods: During selective SLN mapping, 1 to 5 ml of isosulfan blue was injected intradermally around the primary melanoma. From November 1993, to August 1998, 406 patients underwent intraoperative lymphatic mapping with the use of both isosulfan blue and radiocolloid injection. Three cases of selective SLN dissection, in which adverse reactions to isosulfan blue occurred, were reviewed.Results: We report three cases of anaphylaxis after intradermal injection with isosulfan blue of 406 patients who underwent intraoperative lymphatic mapping by using the procedure as described above. The three cases we report vary in severity from treatable hypotension with urticaria and erythema to severe cardiovascular collapse with or without bronchospasm or urticaria.Conclusions: In our series, the incidence of anaphylaxis to isosulfan blue was approximately 1%. Anaphylaxis can be fatal if not recognized and treated rapidly. Operating room personnel who participate in intraoperative lymphatic mapping where isosulfan blue is used must be aware of the potential consequences and be prepared to treat anaphylaxis.

Tumour–induced immune modulation of sentinel lymph nodes

Sentinel lymph nodes (SLNs), being the first nodes to receive lymph from a primary tumour and the preferential site of initial tumour metastases, are intensively exposed to the bioactive products of tumour cells and other associated cells. This makes them ideal for studies of the factors that determine selective tissue susceptibility to metastases. We postulate that tumour-induced immune modulation of SLNs facilitates lymph-node metastases by inhibiting the generation of tumour-specific cytotoxic T cells that are active against tumour cells of primary and metastatic melanomas. Immune modulation of the lymph nodes can be reversed by granulocyte/macrophage colony-stimulating factor (GM-CSF), a finding that has implications for the future therapy of lymph-node metastases.

Cytogenetics of 158 patients with regional or disseminated melanoma. Subset analysis of near-diploid and simple karyotypes.

We report on the cytogenetic analyses of 158 cases of metastatic malignant melanoma, comprised of 63 cases with regional disease (RD) and 95 cases with distant (metastatic) disease (DD). Clonal structural abnormalities were identified in 126 (80%) cases and were significantly increased ( < 0.01 after adjusting for multiple comparisons) on chromosomes (in order of frequency of involvement) 1, 6, 7, 11, 9, and 3. Clustering of breakpoints occurred at 1p36, 1p22-q21, 6p11-q21, 9p, 11q23-qter, 13p (especially for cases with DD), and 19q13. The most common clonal numerical abnormalities, in a subset of 49 near-diploid cases were -10, -22, -9, +7, -19, and -Y. Analysis of chromosome segment gains and losses (CSRP) showed frequent loss of chromosomes 6 and 10, followed by equal rates of involvement of chromosomes 1, 7, and 9. Whole or segmental losses of chromosome 9 (especially 9p) correlate well with recent molecular genetic studies identifying putative suppressor genes, and are also likely important genetic abnormalities. However, based on the frequency of abnormalities in this large series of metastatic melanomas, it is likely that structural abnormalities of 1 and 6, and 10 are important in the pathogenesis of sporadic advanced melanoma.

Melanoma Patients with Positive Sentinel Nodes Who Did Not Undergo Completion Lymphadenectomy: A Multi-Institutional Study

BackgroundCompletion lymph node dissection (CLND) is considered the standard of care in melanoma patients found to have sentinel lymph node (SLN) metastasis. However, the therapeutic utility of CLND is not known. The natural history of patients with positive SLNs who do not undergo CLND is undefined. This multi-institutional study was undertaken to characterize patterns of failure and survival rates in these patients and to compare results with those of positive-SLN patients who underwent CLND.MethodsSurgeons from 16 centers contributed data on 134 positive-SLN patients who did not undergo CLND. SLN biopsy was performed by using each institution’s established protocols. Patients were followed up for recurrence and survival.ResultsIn this study population, the median age was 59 years, and 62% were male. The median tumor thickness was 2.6 mm, 77% of tumors had invasion to Clark level IV/V, and 33% of lesions were ulcerated. The primary melanoma was located on the extremities, trunk, and head/neck in 45%, 43%, and 12%, respectively. The median follow-up was 20 months. The median time to recurrence was 11 months. Nodal recurrence was a component of the first site of recurrence in 20 patients (15%). Nodal recurrence–free survival was statistically insignificantly worse than that seen in a contemporary cohort of patients who underwent CLND. Disease-specific survival for positive-SLN patients who did not undergo CLND was 80% at 36 months, which was not significantly different from that of patients who underwent CLND.ConclusionsThis study underscores the importance of ongoing prospective randomized trials in determining the therapeutic value of CLND after positive SLN biopsy in melanoma patients.

Sentinel Node Staging of Resectable Colon Cancer: Results of a Multicenter Study

Objective and Summary Background Data:Sentinel lymph node (LN) sampling, a technique widely used to manage breast cancer and melanoma, seeks to select LNs that accurately predict regional node status and can be extensively examined to identify nodal metastatic disease not detected by standard histopathological staging. For patients with resectable colon cancer, improved identification of LN disease would significantly advance patient care by identifying patients likely to benefit from adjuvant therapy. This study, conducted by 25 surgeons at 13 institutions, examined whether sentinel node (SN) sampling accurately predicted LN status for patients with resectable colon cancer. Methods:SN sampling involved peritumor injection of 1% isosulfan blue, followed by identification of all LN visualized within 10 minutes. SN sampling was performed on 79 of 91 patients enrolled, followed by multilevel sectioning (MLS) of the nodes and examination by a single study pathologist. Results:By standard histopathology, 7 patients had primary disease that was either benign or not colon cancer and were therefore excluded from further studies. Of 72 colon cancer cases studied, 48 (66%) were node-negative and 24 (33%) contained nodal metastases. SNs were successfully located in 66 cases (92%), with an average of 2.1 nodes per patient. SNs were negative in 14 of 24 node-positive cases (58%). MLS revealed tumor in a SN in 1 of these cases, bringing the false-negative rate of SN examination to 54%. Conclusion:This multi-institutional study found that for patients with node-positive colon cancer, SN examination with MLS failed to predict nodal status in 54% of cases. We conclude that SN sampling with MLS, used alone, is unlikely to improve risk stratification for resectable colon cancer.

Cytogenetic findings in liposarcoma correlate with histopathologic subtypes

The cytogenetic findings in 31 liposarcomas from 26 patients are reported. Four other tumors did not grow. Three histologic types are represented in this analysis. The well‐differentiated liposarcomas were characterized by telomeric associations, large marker chromosomes and ring chromosomes, and in some cases, double minutes. The pleomorphic liposarcomas contained very high clonal chromosomal numbers with near‐tetraploid modes and numerous variable, often unidentifiable, chromosomal abnormalities. The myxoid liposarcomas were characterized primarily by a t(12;16)(q13;pll) as the sole abnormality or additional changes. These results indicate that cytogenetic findings may provide a new criterion, not only for establishing the diagnosis of liposarcoma, but also for differentiating confusing histologic types of liposarcoma and these lesions from other types of sarcomas. Cancer 1992; 69:2484‐2495.

Clinical patterns of metastasis.

In human solid cancer, lymph node status is the most important indicator for clinical outcome. Recent developments in the sentinel lymph node concept and technology have resulted in a more precise way of examining micrometastasis in the sentinel lymph node and the role of lymphovascular system in the facilitation of cancer metastasis.Different patens of metastasis are described with respect to different types of solid cancer. Expect perhaps for papillary carcinoma and sarcoma, the overwhelming evidence is that solid cancer progresses in an orderly progression from the primary site to the regional lymph node or the sentinel lymph node in the majority of cases with subsequent dissemination to the systemic sites. The basic mechanisms of cancer metastasis through the lymphovascular system form the basis of rational therapy against cancer. Beyond the clinical patterns of metastasis, it is imperative to understand the biology of metastasis and to characterize patterns of metastasis perhaps due to heterogeneous clones based on their molecular signatures.