Topographical and Chronological Analysis of Thin Cutaneous Melanoma's Progressions: A Multicentric Study

A great portion of cutaneous melanoma's diagnoses nowadays is attributed to thin tumors with up to 1 mm in Breslow thickness (hereafter thin CMs), which occasionally metastasize. The objective of this study was to identify thin CM's metastatic patterns from a topographical and chronological standpoint. A total of 204 cases of metastatic thin CMs from five specialized centers were included in the study, and corresponding data were collected (clinical, epidemiological, histopathological information of primary tumor and the number, anatomical site, and time intervals of their progressions). First progressions occurred locally, in regional lymph nodes, and in a distant site in 24%, 15% and 61% of cases, respectively, with a median time to first progression of 3.10 years (IQR: 1.09-5.24). The median elapsed time between the first and second progression and between the second and third progression was 0.82 (IQR: 0.34-1.97) and 0.49 (IQR: 0.21-2.30) years, respectively, while the median survival time was about 4 years since first progression. Furthermore, the sequences of locations and time intervals of the progressions were associated with the clinicopathological and demographic features of the primary tumors along with the features of the preceding progressions. In conclusion, the findings of this study describe the natural history of thin CMs, thus highlighting the necessity to identify subgroups of thin CMs at a higher risk for metastasis and contributing to the optimization of the management and follow-up of thin CM patients.

Predictive Values of Pathological and Clinical Risk Factors for Positivity of Sentinel Lymph Node Biopsy in Thin Melanoma: A Systematic Review and Meta-Analysis

Background

The indications for sentinel lymph node biopsy (SLNB) for thin melanoma are still unclear. This meta-analysis aims to determine the positive rate of SLNB in thin melanoma and to summarize the predictive value of different high-risk features for positive results of SLNB.

Methods

Four databases were searched for literature on SLNB performed in patients with thin melanoma published between January 2000 and December 2020. The overall positive rate and positive rate of each high-risk feature were calculated and obtained with 95% confidence intervals (CIs). Both unadjusted odds ratios (ORs) and adjusted ORs (AORs) of high-risk features were analyzed. Pooled effects were estimated using random-effects model meta-analyses.

Results

Sixty-six studies reporting 38,844 patients with thin melanoma who underwent SLNB met the inclusion criteria. The pooled positive rate of SLNB was 5.1% [95% confidence interval (CI) 4.9%-5.3%]. Features significantly predicted a positive result of SLNB were thickness≥0.8 mm [AOR 1.94 (95%CI 1.28-2.95); positive rate 7.0% (95%CI 6.0-8.0%)]; ulceration [AOR 3.09 (95%CI 1.75-5.44); positive rate 4.2% (95%CI 1.8-7.2%)]; mitosis rate >0/mm2 [AOR 1.63 (95%CI 1.13-2.36); positive rate 7.7% (95%CI 6.3-9.1%)]; microsatellites [OR 3.8 (95%CI 1.38-10.47); positive rate 16.6% (95%CI 2.4-36.6%)]; and vertical growth phase [OR 2.76 (95%CI 1.72-4.43); positive rate 8.1% (95%CI 6.3-10.1%)].

Conclusions

The overall positive rate of SLNB in thin melanoma was 5.1%. The strongest predictor for SLN positivity identified was microsatellites on unadjusted analysis and ulceration on adjusted analysis. Breslow thickness ≥0.8 mm and mitosis rate >0/mm² both predict SLN positivity in adjusted analysis and increase the positive rate to 7.0% and 7.7%. We suggest patients with thin melanoma with the above high-risk features should be considered for giving an SLNB.

Association between melanoma thickness and clinical and demographic characteristics

The large-scale implementation of primary and secondary skin cancer prevention strategies in recent decades has led to an increase in the diagnosis of thin melanomas and a decrease in the mean thickness of tumours diagnosed. The number of newly diagnosed thick melanomas, however, has remained stable. To investigate associations between melanoma thickness, clinical presentation and demographic and phenotypic characteristics. The study is based on a cross-sectional study of 1,459 patients with melanoma from a dermatology department at a tertiary hospital in Spain between 2000 and 2017. We analysed associations between median Breslow thickness and demographic, phenotypic, and clinical characteristics, including the method of melanoma detection. Age ≥ 70 years (regression coefficient [RC] =  1.2, 95% CI: 1.1-1.3; p  <  0.001), male sex (RC  =  0.9, 95% CI: 0.8-0.9; p  <  0.001), symptom-based detection (RC  =  1.3, 95% CI: 1.1-1.4; p  <  0.001), and a history of sunburn at the melanoma site (RC  =  0.9, 95% CI: 0.8-0.9; p  =  0.04) were all associated with thicker tumours. Melanomas on the lower extremities, by contrast, were significantly thinner (RC  =  0.9, 95% CI: 0.8-0.9; p = 0.04). Thick melanomas occur preferentially in older men and show changes such as bleeding or an increase in volume or colour. This information should be incorporated into health training and education programs to design better prevention strategies and minimize diagnostic delays.

Peritumoral Immune Infiltrate as a Prognostic Biomarker in Thin Melanoma

Thin melanomas are tumors less than 1 mm thick according to Breslow classification. Their prognosis is in most cases excellent. However, a small subset of these tumors relapses. These clinical findings emphasize the need of novel prognostic biomarkers to identify this subset of tumors. Characterization of tumor immune microenvironment (TIME) is currently investigated as a prognostic and predictive biomarker for cancer immunotherapy in several solid tumors including melanoma. Here, taking into account the limited availability of tumor tissues, by characterizing some of the characteristics of TIME such as number of infiltrating lymphocytes, HLA class I antigen and PD-L1 expression, we show that number of infiltrating CD8+ and FOXP3+ T cells as well as CD8+/FOXP3+ T cell ratio can represent a useful prognostic biomarker in thin melanoma. Although further investigations in a larger patient cohort are needed, these findings have potential clinical significance since they can be used to define subgroups of thin melanoma patients who have a worse prognosis and might need different treatment modalities.

The role of cyclin D1 and Ki-67 in the development and prognostication of thin melanoma

AIMS

Despite their low individual metastatic potential, thin melanomas (≤1 mm Breslow thickness) contribute significantly to melanoma mortality overall. Therefore, identification of prognostic biomarkers is particularly important in this subgroup of melanoma. Prompted by preclinical results, we investigated cyclin D1 protein and Ki-67 expression in in-situ, metastatic and non-metastatic thin melanomas.

METHODS AND RESULTS

Immunohistochemistry was performed on 112 melanoma specimens, comprising 22 in situ, 48 non-metastatic and 42 metastatic thin melanomas. Overall, epidermal and dermal cyclin D1 and Ki-67 expression were semiquantitatively evaluated by three independent investigators and compared between groups. Epidermal Ki-67 expression did not differ statistically in in-situ and invasive melanoma (P = 0.7). Epidermal cyclin D1 expression was significantly higher in thin invasive than in in-situ melanoma (P = 0.003). No difference was found in cyclin D1 expression between metastatic and non-metastatic invasive tumours. Metastatic and non-metastatic thin melanomas did not show significant differences in epidermal expression of Ki-67 and cyclin D1 (P = 0.148 and P = 0.611, respectively). In contrast, strong dermal expression of Ki-67 was more frequent in metastatic than non-metastatic samples (28.6 versus 8.3%, respectively, P = 0.001). The prognostic value of dermal Ki-67 expression was confirmed by multivariate analysis (P = 0.047).

CONCLUSION

We found an increased expression of cyclin D1 in invasive thin melanomas compared to in-situ melanomas, which supports a potential role of this protein in early invasion in melanoma, as suggested by preclinical findings. Moreover, our results confirm that high dermal Ki-67 expression is associated with an increased risk of development of metastasis in thin melanoma and could possibly serve as a prognostic biomarker in clinical practice, especially if combined with additional methods.

A nomogram to predict node positivity in patients with thin melanomas helps inform shared patient decision making

OBJECTIVE

To develop a nomogram to estimate the probability of positive sentinel lymph node (+SLN) for patients with thin melanoma and to characterize its potential impact on sentinel lymph node biopsy (SLNB) rates.

METHODS

Patients diagnosed with thin (0.5-1.0 mm) melanoma were identified from the National Cancer Database 2012 to 2015. A multivariable logistic regression model was used to examine factors associated with +SLN, and a nomogram to predict +SLN was constructed. Nomogram performance was evaluated and diagnostic test statistics were calculated.

RESULTS

Of the 21 971 patients included 10 108 (46.0%) underwent SLNB, with a 4.0% +SLN rate. On multivariable analysis, age, Breslow thickness, lymphovascular invasion, ulceration, and Clark level were significantly associated with SLN status. The area under the receiver operating curve was 0.67 (95% confidence interval, 0.65-0.70). While 15 249 (69.4%) patients had either T1b tumors or T1a tumors with at least one adverse feature, only 2846 (13.0%) had a nomogram predicted probability of a +SLN ≥5%. Using this cut-off, the indication for a SLNB in these patients would be reduced by 81.3% as compared to the American Joint Committee on Cancer 8th edition staging criteria.

CONCLUSIONS

The risk predictions obtained from the nomogram allow for more accurate selection of patients who could benefit from SLNB.

MiRNAs as Potential Prognostic Biomarkers for Metastasis in Thin and Thick Primary Cutaneous Melanomas

BACKGROUND/AIM

The identification of novel prognostic biomarkers for melanoma metastasis is essential to improve patient outcomes. To this aim, we characterized miRNA expression profiles in relation to metastasis in melanoma and correlated miRNAs expression with clinical-pathological factors.

MATERIALS AND METHODS

MiR-145-5p, miR-150-5p, miR-182-5p, miR-203-3p, miR-205-5p and miR-211-5p expression levels were analyzed in primary cutaneous melanomas, including thin and thick melanomas, and in melanoma metastases by quantitative Real-Time PCR.

RESULTS

A significantly lower miR-205-5p expression was found in metastases compared to primary melanomas. Furthermore, a progressive down-regulation of miR-205-5p expression was observed from loco-regional to distant metastasis. Significantly lower miR-145-5p and miR-203-3p expression levels were found in cases with Breslow thickness >1 mm, high Clark level, ulceration and mitotic rate ≥1/mm2 Conclusion: Our findings point to miR-205-5p as potential biomarker of distant metastases and to miR-145-5p and miR-203-3p as markers of aggressiveness in melanoma.

Metastases risk in thin cutaneous melanoma: prognostic value of clinical-pathologic characteristics and mutation profile

Background

A high percentage of patients with thin melanoma (TM), defined as lesions with Breslow thickness ≤1 mm, presents excellent long-term survival, however, some patients develop metastases. Existing prognostic factors cannot reliably differentiate TM patients at risk for metastases.

Objective

We aimed at characterizing the clinical-pathologic and mutation profile of metastatic and not-metastatic TM in order to distinguish lesions at risk of metastases.

Methods

Clinical-pathologic characteristics were recorded for the TM cases analyzed. We used a Next Generation Sequencing (NGS) multi-gene panel to characterize TM for multiple somatic mutations.

Results

A statistically significant association emerged between the presence of metastases and Breslow thickness ≥0.6 mm (p=0.003). None of TM with lymph-node involvement had Breslow thickness <0.6 mm. Somatic mutations were identified in 19 of 21 TM analyzed (90.5%). No mutations were observed in two not-metastatic cases with the lowest Breslow thickness (≤0.4 mm), whereas mutations in more than one gene were detected in one metastatic case with the highest Breslow thickness (1.00 mm).

Conclusion

Our study indicates Breslow thickness ≥0.6 mm as a valid prognostic factor to distinguish TM at risk for metastases.

The natural history of thin melanoma and the utility of sentinel lymph node biopsy

BACKGROUND AND OBJECTIVES

Current literature may overestimate the risk of nodal metastasis from thin melanoma due to reporting of data only from lesions treated with SLNB. Our objective was to define the natural history of thin melanoma, assessing the likelihood of nodal disease, in order to guide selection for SLNB.

METHODS

Retrospective review. The primary outcome was the rate of nodal disease. Clinicopathologic factors were evaluated to find associations with nodal disease.

RESULTS

Five hundred and twelve lesions, follow up available for 488 (median: 48 months). Lesions treated with WLE/SLNB compared to WLE alone were more likely to have high-risk features. The rate of nodal disease was higher in the WLE/SLNB group (24 positive SLNB, five false-negative SLNB with nodal recurrence: 10.2%) compared to WLE alone (four nodal recurrences: 2.0%). Univariate analysis showed age ≤45, Breslow depth ≥0.85 mm, mitotic rate >1 mm² , and ulceration were associated with nodal disease. Multivariate analysis confirmed the association of age ≤45 and ulceration.

CONCLUSIONS

SLNB for melanoma 0.75-0.99 mm should be considered in patients age ≤45, Breslow depth ≥0.85 mm, mitotic rate >1 mm² , and/or with ulceration. Thin melanoma <0.85 mm without high-risk features may be treated with WLE alone.

Using global gene expression to discriminate thin melanomas with poor outcomes

Most melanomas present as thin lesions (≤1.0 mm) with a good prognosis; however, a small percentage of patients with thin lesions experience recurrence or metastasis. The aim of our study was to identify a distinct pattern of gene expression within thin melanomas known to have eventually metastasized to regional lymph nodes or distant sites compared with those that followed the typical course with good response to wide local excision alone. Patients who were disease-free for a minimum of 10 y served as controls (n = 10) to the experimental group who developed metastasis (n = 9). Laser capture microdissection was used to specifically isolate cancer cells from formalin-fixed paraffin-embedded tissue with subsequent gene expression analysis on Affymetrix Human Transcriptome Array 2.0 Arrays. Although gene expression differences were observed between the patients with thin melanoma with poor clinical outcome and those with good clinical outcome, neither the number of genes nor the magnitude of the fold difference was very substantial or significant. Cluster analysis with this subset of genes could definitively separate a subset of the poor responders from the good responders, but there remained a mixed group of tumors that could not be predicted from gene expression alone. Pathway analysis identified cellular processes that were regulated based on the response, including categories commonly associated with melanoma progression. Ultimately, we concluded that there were very few differences between these groups. Future research will be required and investigation of the mutational landscape may be another strategy to uncover genomic changes that drive recurrence and metastasis in thin melanoma.

Implementation of the 7th edition AJCC staging system: Effects on staging and survival for pT1 melanoma. A Dutch population based study

In the 7^th edition of the AJCC staging system, the mitotic rate criterion replaced Clark level to increase correct classification of high-risk thin melanoma patients (pT1B). Additionally, sentinel node biopsy (SNB) was recommended for nodal staging of pT1B melanomas. The aim of this article was to evaluate the effects on pT1 substaging and clinical implications in the national pT1 melanoma population. All pT1 melanomas diagnosed in the Netherlands between 2003 and 2014 were selected from the Netherlands Cancer Registry (IKNL). Patients were stratified by cohort according to AJCC edition: (1) 2003-2009 (6^th ) and (2) 2010-2014 (7^th ). Relative survival was calculated to estimate melanoma-specific survival. A total of 29.546 pT1 melanoma patients were included. The pT1b proportion increased from 10.1% in Cohort 1 to 21.5% in Cohort 2. The proportion of performed SNBs per cohort increased: for pT1b melanomas alone from 4.5% to 13.0%. SNB positivity rate decreased from 10.5% to 8.8% for the entire pT1 population, and for pT1b melanomas from 11.3% to 8.6%. At 5 years, the relative survival rate was similar for pT1a and pT1b in both cohorts, namely, pT1a 100% vs pT1b 97% (Cohort 1), and pT1a 100% vs pT1b 98% (Cohort 2). The 7^th edition of the AJCC staging system has caused an increased number of patients to undergo SNB, without an increase in SNB positivity rate. Survival between pT1 subgroups remains similar. The mitotic rate criterion for pT1b classification and the recommendation to perform SNB for pT1b melanomas should be reconsidered.

Regression in thin melanoma is associated with nodal recurrence after a negative sentinel node biopsy

Prognostic markers for nodal metastasis in thin melanoma patients are debated. We present a single institution study looking at factors predictive of nodal disease in thin melanoma patients. Retrospective review from 1997 to 2012 identified 252 patients with thin melanoma (≤1 mm) who underwent a sentinel lymph node biopsy (SLNB). Node‐positive patients included positive SLNB patients and negative SLNB patients who developed a nodal recurrence (false‐negative SLNB). Clinicopathologic characteristics were correlated with nodal status and outcome. Median follow‐up was 45.5 months. Twelve of 252 patients (4.8%) were node‐positive including six positive SLNB (2.4%) and six false‐negative SLNB (2.4%) patients. No clinicopathologic factors were significantly correlated with nodal disease. For the six false‐negative SLNB patients, median time to nodal recurrence was 37.5 months. Regression was seen in only 16% of cases, but the rate increased to 60% for false‐negative SLNB cases. Both age (odds ratio [OR]: 1.09, 95% CI: 1.01–1.17; P = 0.02) and regression (OR: 8.33, 95% CI: 1.34–52.63; P = 0.02) were significantly associated with nodal recurrence after a negative SLNB on univariable analysis. Nodal disease in thin melanoma patients was seen in 4.8% of cases. Although regression was not correlated with nodal metastasis, it was correlated with a false‐negative SLNB. Patients with thin melanoma and regression may need more intensive surveillance after a negative SLNB. Further study is needed to determine if the same immune mechanisms that result in regression in primary tumors also lead to regression in lymph nodes, which may decrease detection of melanoma nodal metastases.

A retrospective, multicenter analysis of the predictive value of mitotic rate for sentinel lymph node (SLN) positivity in thin melanomas

BACKGROUND

There is a paucity of studies to substantiate whether the presence of a single mitosis justifies sentinel lymph node (SLN) biopsy (SLNB) in thin melanomas.

OBJECTIVE

We sought to determine if mitotic rate is associated with SLNB outcome when taking into account other prognostic factors.

METHODS

All cases of melanoma that underwent SLNB in the province of Alberta, Canada, between 2007 and 2013 were reviewed through a provincial tumor database.

RESULTS

A total of 1072 patients fulfilled inclusion criteria. When analyzing all melanomas regardless of thickness, mitotic rate was a good predictor of SLN status. When stratified by Breslow thickness, only intermediate melanomas (1.01-2.0 mm) demonstrated a significant relationship between mitotic rate and positive SLN status (P = .010). For melanomas 1 mm or smaller, mitotic rate was not associated with SLN status. A statistically significant interaction was identified between Breslow thickness and mitotic rate such that for decreasing Breslow depth, the effect of mitotic rate on SLNB status diminished (P = .028).

LIMITATIONS

The study was retrospective in nature. There is underlying variability in mitotic rate reporting methods over time, and between different dermatopathologists.

CONCLUSIONS

Mitotic rate does not have unequivocal utility in predicting SLNB status in thin melanomas. There is a significant interaction between mitotic rate and Breslow depth, such that the predictive value of mitotic rate on SLN positivity may be dependent on Breslow thickness.

Assessment of tumor mitotic rate in primary cutaneous malignant melanomas 1 mm or less in thickness

BACKGROUND

Tumor mitotic rate in thin melanomas is recognized as a powerful, independent prognostic factor predicting survival. In nonulcerated cases, the presence of any dermal mitotic activity upstages the disease to pT1b. The extent to which tissue should be histologically examined to assess mitogenicity, however, has not been studied.

OBJECTIVE

We sought to determine whether in staging thin melanomas, there is a significant benefit in examining numerous tissue sections containing invasive disease.

METHOD

In all, 71 cases of thin cutaneous melanomas diagnosed between January 2012 and June 2013 were identified after a search performed on the Pathlab database. The slides were retrieved and reviewed retrospectively, comparing the identification of the first dermal tumor mitotic figure, if present, at 4 check-points: the first, third, fifth, or tenth tissue section examined.

RESULTS

A statistically significant difference in identification of the first dermal mitotic figure was found in examining 1 versus 3 tissue sections (P = .0411). No significant difference was found in examining numerous tissue sections.

LIMITATIONS

This was a retrospective study from a single institution with a limited number of participants.

CONCLUSION

In staging thin melanomas without ulceration, the optimal number of sections to assess is 3. No additional benefit is gained by examining numerous tissue sections.