New developments in melanoma: utility of ultrasound imaging (initial staging,follow-up and pre-SLNB)

Melanoma incidence is still increasing, but the mortality rate has remained unchanged. Lymph node metastases are the single most important prognostic factor for stage I/II melanoma patients. Currently, the standard of care with regard to the staging of these patients is the surgical sentinel node procedure. Ultrasound is not routine for the diagnostic work-up of primary melanomas. Some may use ultrasound for the preoperative assessment of the tumor thickness and lymphatic drainage, but this has not found wide application. For the follow-up of melanoma patients, ultrasound has been proven to be superior to physical examination for the detection of lymph node metastases. A meta-analysis has shown that ultrasound is superior to computed tomography (CT) and/or positron emission tomography (PET)-CT for the detection of lymph node metastases, whereas PET-CT was superior for the detection of distant visceral metastases. Ultrasound of regional lymph nodes has been incorporated into many national guidelines across Europe and in Australia for the follow-up of melanoma patients. A new avenue for ultrasound (US)-guided fine-needle aspiration cytology (FNAC) is the pre-sentinel node modality. Like the situation in breast and thyroid cancer, US-FNAC, a minimally invasive procedure, may decrease the need for surgical sentinel node staging. New ultrasound morphology criteria have significantly increased the sensitivity of this technique. Peripheral perfusion is an early sign of metastases (77% sensitivity, 52% positive-predictive value), whereas balloon-shaped lymph node was a late sign of metastases (30% sensitivity, 96% positive-predictive value). Together, these new ultrasound morphology criteria were able to accurately demonstrate metastases in 65% of sentinel node-positive patients. Future perspectives of ultrasound in melanoma include the start of a large multicenter, multicountry validation study – USE-FNAC – by the European Organisation for Research and Treatment of Cancer (EORTC) Melanoma Group. In light of new and promising adjuvant therapies, the need for ultrasound staging might increase rapidly.     

Sentinel lymph node biopsy in patients with Stage I/II melanoma: Clinical experience and literature review

BACKGROUND: The sentinel lymph node (sN) represents one of the most powerful predictors of the outcome of patients with Stages I and II cutaneous melanoma, and may be relevant for the therapeutic planning of early-stage melanoma patients. Since adopting the technique of lymphatic mapping with vital blue dye (Patent Blue-V) in July 1993, we have periodically up-dated the methodology and revised our results in order to define the contribution of radio-guided surgery (RGS) to the detection of the sN as well as the role of intraoperative frozen section examination of the sN. MATERIALS AND METHODS: Between July 1993 and December 1997, 180 patients with clinically node-negative primary cutaneous melanoma (Stages I-II) underwent sN biopsy followed by "selective lymph node dissection" (SLND) whenever sN metastasis was detected. Presently, complete data are available in 165 patients who were divided into two consecutive subsets of 39 and 126 patients, based on the technique for the identification of the sN: Patent Blue-V only or Patent Blue-V associated to RGS. Moreover, in this second subset of patients intraoperative frozen section findings were compared with definitive pathologic examination. RESULTS: As regards the first subset of 39 patients (17 males and 22 females; mean age 51.3 years), the sN was identified in 35 patients (89.7%); 8 patients (22.8%) were found to have metastatic melanoma cells in their sN, and they all underwent SLND of the affected basin. As regards the second set of 126 patients (54 males and 72 females; mean age 53.5 years), the sN was detected in every case by means of the combined technique (Patent Blue-V and RGS): in 4 of 126 patients (3.2%), the sN was detected by means of RGS only whereas in no patient was the sN detected by Patent Blue-V only. Frozen section examination was performed in 123 of 126 patients who had sN detection by Patent Blue-V and RGS, and the intraoperative examination had a sensitivity of 66.6% (22 of 33), specificity of 100% (90 of 90), negative predictive value of 89.1% (90 of 101), and accuracy of 91% (112 of 123). The benefit of frozen section examination in avoiding a two-stage procedure was 17.9% (22 of 123 patients). In patients with thicker lesions (pT(3)-pT(4)), the sensitivity and the benefit of intraoperative examination were 76% (19 of 25) and 32% (19 of 59 patients), respectively. CONCLUSIONS: Sentinel node lymphadenectomy can be better accomplished when both procedures (lymphatic mapping with Patent Blue-V and RGS) are used because the two methods look quite complementary. In fact, the use of the radiocolloid mapping allows to detect a hot spot in the regional basin prior to making the skin incision in order to perform a minimal invasive access, and it may also more accurately differentiate the true sN from a secondary echelon node (non-sN). The use of frozen section examination should be restricted to patients with pT(3)-pT(4) primary melanoma, due to the higher sensitivity and benefit in terms of avoiding a two-stage operative procedure.     

Fine-needle-aspiration cytodiagnosis of recurrent malignant melanoma

Sixty-four patients with melanoma (28 with clinical stage I disease and 36 with clinical stages II through IV disease) were fine-needle biopsied on suspicion of recurrent melanoma. Eighty-four biopsies were aspirated percutaneously and three at exploratory laparotomy. A tumor mass was present at 81 biopsies. The remaining biopsies were taken with theguidance of liver scan or fluoroscopy. In the patients with the diagnosis of recurrent malignant melanoma the cytodiagnosis was correct in 45 patients out of 47. One patient was diagnosed as breast cancer and one as malignant mesenchymal tumor. Of 40 biopsies considered normal, three were revised to be melanoma. No false-positive diagnosis was found. The frequency of false-negative diagnosis was 6%. Fine-needle-aspiration cytology is a suitable method t o establish a correct diagnosis when there is a suspicion of recurrent disease during the follow-up of melanoma patients. The high diagnostic accuracy in patients with enlarged lymph nodes is excellent and makes the method preferable to diagnostic surgical excision biopsies.     

Trametinib in metastatic melanoma

The treatment of metastatic melanoma is rapidly changing. In 2002, the BRAF mutation was described in over 50% of melanomas and led to the first BRAF inhibitor, vemurafenib, being approved for clinical use in 2011. Clinical responses are often rapid but duration of response is limited due to the development of resistance. MEK is the next downstream target from BRAF in the MAP kinase pathway. Trametinib was the first MEK inhibitor to be approved for clinical use in 2013. Preclinical studies demonstrated a delay in resistance and a reduction in cutaneous toxicity by combined BRAF and MEK inhibition. Here, we review the rationale for clinical development of trametinib and give an update on recent clinical trials of trametinib alone and in combination with braf inhibition in melanoma.     

Diagnostic challenges of metastatic spindle cell melanoma on fine‐needle aspiration specimens

BACKGROUND

Spindle cell melanoma is a morphologic variant of melanoma that can be difficult to diagnose on specimens obtained via fine‐needle aspiration (FNA). Published cytology studies concerning this entity were based for the most part on small series. In the current study, a large series of metastatic spindle cell melanoma is described and the diagnostic pitfalls present in FNA samples addressed.

METHODS

The authors retrospectively reviewed the cytologic features of 81 metastatic spindle cell melanoma specimens obtained from 67 patients. Corresponding primary tumors or metastatic tumors taken elsewhere from the same patient were also evaluated.

RESULTS

The cytologic smears were mostly cellular and comprised of predominantly spindle tumor cells that frequently formed cohesive fascicles or whorls intermingled with scattered epithelioid tumor cells. The classic cytologic characteristics of conventional melanoma (predominantly dyshesive cellular distribution, cytoplasmic melanin pigments, intranuclear pseudoinclusions, macronucleoli, and binucleation or multinucleation) were noted infrequently or, if present, were more readily found in coexisting epithelioid cells. Remarkably, 9% of the cases failed to demonstrate any of the above classic characteristics. In addition, spindle cells demonstrated a wide range of cytologic atypia, from deceptively bland cells resembling reactive fibroblasts to those indistinguishable from pleomorphic high‐grade sarcomatous neoplasms. When the morphologic features were compared with those of the primary tumor or metastatic melanoma taken elsewhere from the same patient, cell type discrepancy was found in 20% of the cases in that the previous counterparts demonstrated the epithelioid cell type. Spindle cells also tended to lose immunoexpression of melanoma markers.

CONCLUSIONS

Spindle cell melanoma infrequently demonstrates the diagnostic cytologic features and immunoreactivity of conventional melanoma. Varying degrees of cytologic atypia and possible cell type differences from the primary counterpart or metastatic melanoma occurring elsewhere are additional sources of diagnostic challenges, especially in the metastatic setting. Familiarity with cytologic features, combined with clinical and immunoperoxidase findings, is required to avoid misinterpretation. Cancer (Cancer Cytopathol) 2008. © 2008 American Cancer Society.     

Sentinel node biopsy in skin melanoma patients--measurements of absorbed doses of radiation to the hands of medical staff

BACKGROUND AND OBJECTIVES: The goal of this study was to measure absorbed doses of radiation to the hands of medical staff performing sentinel node biopsy (SNB) in skin melanoma patients. METHODS: The study was conducted from January 2004 to May 2004, during SNBs (lymphoscintigraphy-(99m)Tc on albumin carrier, surgery after 24 hr; blue dye; intraoperative detection of gamma radiation) in 22 skin melanoma patients. During lymphoscintigraphy and surgical procedures, 57 highly sensitive thermoluminescent dosimeters (TLDs) were placed on different parts of the hands of the medical staff. RESULTS: Mean doses of radiation recorded on different parts of the hands of the physician injecting the radiotracer ranged from 2.43 to 84.11 microSv for single procedures, ranged from 3.20 to 5.84 microSv for the hands of surgeon, and ranged from 2.65 to 5.47 microSv for the hands of the remaining members of the medical staff. Absorbed doses of radiation to the hands of helping medical staff present in operating room was only slightly lower than absorbed doses to the hands of operating surgeon and assistant surgeon. CONCLUSION: The maximum recorded dose during this study was 1,900 times smaller than the current 1-year dose limit recommended by the International Commission on Radiological Protection (ICRP).     

Sentinel lymph node biopsy in melanoma patients: the medical oncologist's perspective

With the advent of sentinel node (sN) biopsy in melanoma patients, elective lymph node dissection (ELND) can be considered an exceeded procedure. Regardless of the possible therapeutic benefits, sN biopsy efficiently predicts prognosis avoiding the morbidity rate of ELND. The importance of the sN is underlined by multivariate analyses, which show that the sN status represents the most important prognostic factor influencing disease-free and distant disease-free survival in patients with stage I and II melanoma. Moreover, sN biopsy provides a minimally invasive method for identifying those patients with subclinical nodal metastasis who actually have stage III disease, with a very high risk of occult distant metastases and who may benefit by adjuvant therapy.     

Overcoming resistance to BRAF inhibition in BRAF-mutated metastatic melanoma

Almost 50% of metastatic melanoma patients harbor a BRAF^V600 mutation andthe introduction of BRAF inhibitors has improved their treatment options. BRAF inhibitors vemurafenib and dabrafenib achieved improved overall survival over chemotherapy and have been approved for the treatment of BRAF-mutated metastatic melanoma. However, most patients develop mechanisms of acquired resistance and about 15% of them do not achieve tumor regression at all, due to intrinsic resistance to therapy. Moreover, early adaptive responses limit the initial efficacy of BRAF inhibition, leading mostly to incomplete responses that may favor the selection of a sub-population of resistant clones and the acquisition of alterations that cause tumor regrowth and progressive disease.The purpose of this paper is to review the mechanisms of resistance to therapy with BRAF inhibitors and to discuss the strategies to overcome them based on pre-clinical and clinical evidences.     

Glypican‐3 protein expression in primary and metastatic melanoma

BACKGROUND:

The incidence of melanoma is increasing. Fine‐needle aspiration (FNA) is critical in documenting recurrent/metastatic disease in established cases. The potential of metastatic melanoma (MM) to mimic epithelial tumors presents a diagnostic dilemma. In liver FNA, the distinction between hepatocellular carcinoma (HCC) and MM is a frequent challenge. Glypican‐3 (GPC3), a heparan sulfate proteoglycan, is a highly sensitive and specific marker for HCC. Serum GPC3 was shown to be expressed in 40% of primary melanomas (PMs), but to the authors' knowledge no tissue studies to date have assessed GPC3 expression in MM. In this study, GPC3 protein expression was investigated in FNAs from MM, and in corresponding histologic sections from the primary tumors.

METHODS:

Sixty archival, direct FNA smears or CytoLyt‐fixed samples from 50 patients with MM were retrieved together with formalin‐fixed, paraffin‐embedded specimens available from 17 corresponding PMs. All cases were stained with anti‐GPC3 antibody. FNA and core biopsy specimens from HCCs and benign liver were used as positive and negative controls. GPC3 expression was divided into 2 categories: negative (negative or weak cytoplasmic staining) and positive (moderate or strong cytoplasmic with membranous accentuation).

RESULTS:

All FNAs from MM cases were negative (0 of 60) for GPC3. The exact 95% Clopper‐Pearson confidence interval was 0.0% to 5.96%. Only 1 case of PM (1 of 17; 5.9%) demonstrated weak focal cytoplasmic staining (regarded as negative).

CONCLUSIONS:

In the current study, all MM and PM cases in archival FNAs and tissue sections were found to be negative for GPC3. These data suggest that GPC3 is not expressed in melanoma using the 1G12 clone. Cancer (Cancer Cytopathol) 2009. © 2009 American Cancer Society.     

Sentinel lymph node biopsy versus observation in thick melanoma: A multicenter propensity score matching study

The clinical value of sentinel lymph node (SLN) biopsy in thick melanoma patients (Breslow >4 mm) has not been sufficiently studied. The aim of the study is to evaluate whether SLN biopsy increases survival in patients with thick cutaneous melanoma, and, as a secondary objective, to investigate correlations between survival and lymph node status. We included 1,211 consecutive patients with thick melanomas (>4 mm) registered in the participating hospitals' melanoma databases between 1997 and 2015. Median follow‐up was 40 months. Of these patients, 752 were matched into pairs by propensity scores based on sex, age, tumor location, histologic features of melanoma, year of diagnosis, hospital and adjuvant interferon therapy. The SLN biopsy vs. observation was associated with better DFS [adjusted hazard ratio (AHR), 0.74; 95% confidence interval (CI) 0.61–0.90); p = 0.002] and OS (AHR, 0.75; 95% CI, 0.60–0.94; p = 0.013) but not MSS (AHR, 0.84; 95% CI, 0.65–1.08; p = 0.165). SLN‐negative patients had better 5‐ and 10‐year MSS compared with SLN‐positive patients (65.4 vs. 51.9% and 48.3 vs. 38.8%; p = 0.01, respectively). As a conclusion, SLN biopsy was associated with better DFS but not MSS in thick melanoma patients after adjustment for classic prognostic factors. SLN biopsy is useful for stratifying these patients into different prognostic groups.     

Molecular stratification of metastatic melanoma using gene expression profiling : Prediction of survival outcome and benefit from molecular targeted therapy

Melanoma is currently divided on a genetic level according to mutational status. However, this classification does not optimally predict prognosis. In prior studies, we have defined gene expression phenotypes (high-immune, pigmentation, proliferative and normal-like), which are predictive of survival outcome as well as informative of biology. Herein, we employed a population-based metastatic melanoma cohort and external cohorts to determine the prognostic and predictive significance of the gene expression phenotypes. We performed expression profiling on 214 cutaneous melanoma tumors and found an increased risk of developing distant metastases in the pigmentation (HR, 1.9; 95% CI, 1.05-3.28; P=0.03) and proliferative (HR, 2.8; 95% CI, 1.43-5.57; P=0.003) groups as compared to the high-immune response group. Further genetic characterization of melanomas using targeted deep-sequencing revealed similar mutational patterns across these phenotypes. We also used publicly available expression profiling data from melanoma patients treated with targeted or vaccine therapy in order to determine if our signatures predicted therapeutic response. In patients receiving targeted therapy, melanomas resistant to targeted therapy were enriched in the MITF-low proliferative subtype as compared to pre-treatment biopsies (P=0.02). In summary, the melanoma gene expression phenotypes are highly predictive of survival outcome and can further help to discriminate patients responding to targeted therapy.     

Meta‐analysis of sentinel lymph node positivity in thin melanoma (≤1 mm)

BACKGROUND:

Despite the lack of an established survival benefit of sentinel lymph node (SLN) biopsy, this technique has been increasingly applied in the staging of thin (≤1 mm) melanoma patients, without clear evidence to support this recommendation. The authors performed a meta‐analysis to estimate the risk, potential predictors, and outcome of SLN positivity in this group of patients.

METHODS:

MEDLINE, EMBASE, and Cochrane databases were searched for rates of SLN positivity in patients with thin melanoma. The methodologic quality of included studies was assessed using the Methodological Index for Non‐Randomized Studies criteria. Heterogeneity was assessed using the Cochran Q statistic, and publication bias was examined through funnel plot and the Begg and Mazumdar method. Overall SLN positivity in thin melanoma patients was estimated using the DerSimonial‐Laird random effect method.

RESULTS:

Thirty‐four studies comprising 3651 patients met inclusion criteria. The pooled SLN positivity rate was 5.6%. Significant heterogeneity among studies was detected (P = .005). There was no statistical evidence of publication bias (P = .21). Eighteen studies reported select clinical and histopathologic data limited to SLN‐positive patients (n = 113). Among the tumors from these patients, 6.1% were ulcerated, 31.5% demonstrated regression, and 47.5% were Clark level IV/V. Only 4 melanoma‐related deaths were reported.

CONCLUSIONS:

Relatively few patients with thin melanoma have a positive SLN. To the authors' knowledge, there are no clinical or histopathologic criteria that can reliably identify thin melanoma patients who might benefit from this intervention. Given the increasing diagnosis of thin melanoma, in addition to the cost and potential morbidity of this procedure, alternative strategies to identify patients at risk for lymph node disease are needed. Cancer 2009. © 2008 American Cancer Society.