Outcome of sentinel lymph node biopsy and prognostic implications of regression in thin malignant melanoma

Histopathologic regression in patients with primary cutaneous melanoma undergoing sentinel lymph node biopsy is associated with favorable survival and, after metastasis, with improved progression-free survival on immune checkpoint inhibitor therapy: A single-institutional cohort study

BACKGROUND

Histopathologic regression of cutaneous melanoma is considered a favorable prognostic factor, but its significance in clinical practice remains controversial.

OBJECTIVE

To investigate the prognostic importance of regression in patients with primary cutaneous melanoma undergoing sentinel lymph node (SLN) biopsy and to assess its significance in patients progressing to an unresectable stage requiring systemic therapy.

METHODS

We retrospectively reviewed patients with newly diagnosed melanoma undergoing SLN biopsy between 2010 and 2015 and available information on histopathologic regression (n = 1179). Survival data and associations of clinical variables with SLN status were assessed.

RESULTS

Patients with regressive melanoma showed favorable relapse-free (hazard ratio [HR], 0.52; P = .00013), distant metastasis-free (HR, 0.56; P = .0020), and melanoma-specific survival (HR, 0.35; P = .00053). Regression was associated with negative SLN (odds ratio, 0.48; P = .0077). In patients who progressed to an unresectable stage, regression was associated with favorable progression-free survival under immune checkpoint inhibition (HR, 0.43; P = .031) but not under targeted therapy (HR, 1.14; P = .73) or chemotherapy (HR, 3.65; P = .0095).

LIMITATIONS

Retrospective, single-institutional design.

CONCLUSIONS

Regression of cutaneous melanoma is associated with improved prognosis in patients eligible for SLN biopsy as well as in patients with unresectable disease receiving systemic therapy with immune checkpoint inhibitors.

Histological regression in melanoma: impact on sentinel lymph node status and survival

Regression in melanoma is an immunological phenomenon that results in partial or complete replacement of the tumor with variably vascular fibrous tissue, often accompanied by pigment-laden macrophages and chronic inflammation. In some cases, tumor-infiltrating lymphocytes (TILs) may represent the earliest phase of this process. The prognostic significance of regression has long been a matter of debate, with inconsistent findings reported in the literature to date. This study sought to determine whether regression in primary cutaneous melanomas predicted sentinel lymph node (SLN) status and survival outcomes in a large cohort of patients managed at a single centre. Clinical and pathological parameters for 8,693 consecutive cases were retrieved. Associations between regression and SLN status, overall survival (OS), melanoma-specific survival (MSS) and recurrence-free survival (RFS) were investigated using logistic and Cox regression. Histological evidence of regression was present in 1958 cases (22.5%). Regression was significantly associated with lower Breslow thickness, lower mitotic rate, and absence of ulceration (p < 0.0001). Multivariable analysis showed that regression in combination with TILs independently predicted a negative SLN biopsy (OR 0.33; 95% C.I. 0.20-0.52; p < 0.0001). Patients whose tumors showed both regression and TILs had the highest 10-year OS (65%, 95% C.I. 59-71%), MSS (85%, 95% C.I. 81-89%), and RFS (60%, 95% C.I. 54-66%). On multivariable analyses, the concurrent presence of regression and TILs independently predicted the lowest risk of death from melanoma (HR 0.69; 95% C.I. 0.51-0.94; p = 0.0003) as well as the lowest rate of disease recurrence (HR 0.71; 95% C.I. 0.58-0.85; p < 0.0001). However, in contrast, in the subgroup analysis of Stage III patients, the presence of regression predicted the lowest OS and RFS, with MSS showing a similar trend. Overall, these findings indicate a prognostically favorable role of regression in primary cutaneous melanoma. However, in Stage III melanoma patients, regression may be a marker of more aggressive disease.

Sentinel lymph node biopsy in acral melanoma: A Korean single-center experience with 107 patients (2006-2018)

BACKGROUND

Sentinel lymph node biopsy (SLNB) of primary cutaneous melanoma as an important staging method has not been popularly undertaken in Korea and only a few studies with small patient numbers have been published.

AIM

We examined the clinical feasibility and overall outcomes of SLNB in acral melanoma (AM) of Korean in Kyungpook National University Hospital (KNUH) over the past 13 years.

METHODS

SLNB in AM patients during 2006-2018 were analyzed retrospectively for sentinel lymph node (SLN) harvesting rate, positivity rate, positivity-relevant overall survival (OS) and disease-free survival (DFS), and its side effects.

RESULTS

A total of 109 AM patients who underwent SLNB were enrolled. Harvested nodes were identified from 107 patients and SLN harvesting rate was 98.2%. The mean Breslow thickness (±standard deviation) was 3.38 ± 3.03 mm, and the proportion of ulcerated melanomas was 64%. Twenty-two (20.6%) had a tumor-positive SLN and, among them, 82% (18/22) underwent immediate complete lymph node dissection (CLND). The metastasis-positive nodal basin after CLND was detected in 16.7% of cases (3/18). Tumor-negative SLN cohorts showed significantly better OS and DFS than tumor-positive ones (P = 0.006 and P < 0.001 for each). Two side effects, one seroma and one lymphocele, were observed without major sequelae.

CONCLUSION

SLNB, crucial management of melanoma, proved its efficacy to predict patients' prognosis and could be performed successfully and safely in Korean AM patients by interdisciplinary cooperation between dermatology and other surgical departments. SLN(-) showed significantly better OS and DFS than SLN(+). Significant risk factors for DFS were Breslow thickness, the presence of ulceration and the presence of SLN metastasis. SLNB should be encouraged in order to stage melanoma accurately and direct the proper management in Korean AM.

Prognostic significance of regression and mitotic rate in head and neck cutaneous melanoma

Importance

While regression is a commonly reported microscopic feature of melanoma, its prognostic significance is unclear.

Objective

To examine the impact of regression on sentinel node status and the likelihood of recurrence in primary cutaneous melanoma of the head and neck.

Design

Retrospective analysis of 191 adults who underwent surgical management for primary cutaneous melanoma of the head and neck between May 2002 and March 2019.

Setting

Tertiary academic center.

Participants

Patients appropriate for the study were identified by the Academic Health Center Information Exchange using a list of current procedural terminology codes. One hundred and ninety‐one cases of invasive melanoma of the head and neck were included from 830 patients identified. Clinical features assessed for each patient included age, sex, location of primary lesion, date of diagnosis, and current disease status (alive with or without disease). Histologic features assessed were histological melanoma subtype (nodular vs non‐nodular), Breslow thickness, Clark level, presence/absence of ulceration, mitotic rate per square millimeter, and regression. If applicable, sentinel lymph node biopsy (SLNB) status, date of recurrence, interval treatments, and date of death related to melanoma were recorded. Exclusion criteria included melanoma outside the anatomic parameters of head and neck, ocular or choroidal melanoma, mucosal melanoma, metastatic melanoma to the head or neck with no known primary tumor, melanoma of the head or neck with no surgical intervention, and non‐melanoma skin cancers of the head and neck.

Intervention/Exposure

Surgery for cutaneous melanoma of the head and neck.

Main Outcome(s) and Measure(s)

The association between presence of regression and Breslow thickness, sentinel node status, and recurrence.

Results

Of the 191 patients identified, 30.9% were female and 69.1% were male with a mean age at diagnosis of 62.6 (range 20‐97) years. Mean Breslow thickness was 1.2 mm in those with regression and 2.0 mm in those without regression. In patients with regression, 17.6% had a positive sentinel node, and 13.0% experienced a recurrence. In patients without regression, 26.5% had a positive sentinel node, and 31.4% experienced a recurrence. When adjusted for other factors above, regression was not associated with positive sentinel node (odds ratio [OR] = 0.59, 95% confidence interval [CI] = 0.13‐2.00) or recurrence (OR = 0.33, CI = 0.07‐1.01). Mitotic rate >2 was associated with recurrence (OR = 2.71, CI = 1.11‐6.75, P = .03).

Conclusions and Relevance

Patients with presence of regression had thinner melanomas and trended toward decreased rates of sentinel node positivity and recurrence, suggesting regression may not be a negative prognostic indicator in patients with cutaneous melanoma of the head and neck.

Current controversies in early-stage melanoma: Questions on incidence, screening, and histologic regression

In the first article in this continuing medical education series we review controversies and uncertainties relating to the epidemiology and initial diagnosis of localized cutaneous melanoma (ie, stage 0, I, or II). Many of these issues are unsettled because of conflicting evidence. Melanoma incidence appears to be increasing, yet its basis has not been fully explained. Despite the advantages of early detection, the US Preventive Services Task Force does not recommend skin screening for the general population. Occasionally, biopsy specimens of melanoma will show histologic regression, but the prognostic importance of this phenomenon is uncertain. Some practitioners recommend obtaining a sentinel lymph node biopsy specimen for thin melanomas showing regression, although this histologic finding is not part of the staging system for thin melanomas. Our goal is to provide the clinician who cares for patients with (or at risk for) melanoma with up-to-date contextual knowledge to appreciate the multiple sides of each controversy so that they will be better informed to discuss these issues with their patients and their families.

Vertical Growth Phase as a Prognostic Factor for Sentinel Lymph Node Positivity in Thin Melanomas: A Systematic Review and Meta-Analysis

BACKGROUND

The 2010 American Joint Committee on Cancer guidelines recommended consideration of sentinel lymph node biopsy for thin melanoma (Breslow thickness <1.0 mm) with aggressive pathologic features such as ulceration and/or high mitotic rate. The therapeutic benefit of biopsy-based treatment remains controversial. The authors conducted a meta-analysis to estimate the risk and outcomes of sentinel lymph node positivity in thin melanoma, and examined established and potential novel predictors of positivity.

METHODS

Three databases were searched by two independent reviewers for sentinel lymph node positivity in patients with thin melanoma. Study heterogeneity, publication bias, and quality were assessed. Data collected included age, sex, Breslow thickness, mitotic rate, ulceration, regression, Clark level, tumor-infiltrating lymphocytes, and vertical growth phase. Positivity was estimated using a random effects model. Association of positivity and clinicopathologic features was investigated using meta-regression.

RESULTS

Ninety-three studies were identified representing 35,276 patients with thin melanoma who underwent sentinel lymph node biopsy. Of these patients, 952 had a positive sentinel lymph node biopsy, for an event rate of 5.1 percent (95 percent CI, 4.1 to 6.3 percent). Significant associations were identified between positivity and Breslow thickness greater than 0.75 mm but less than 1.0 mm, mitotic rate, ulceration, and Clark level greater than IV. Seven studies reported on vertical growth phase, which was strongly associated with positivity (OR, 4.3; 95 percent CI, 2.5 to 7.7).

CONCLUSIONS

To date, this is the largest meta-analysis to examine predictors of sentinel lymph node biopsy positivity in patients with thin melanoma. Vertical growth phase had a strong association with biopsy positivity, providing support for its inclusion in standardized pathologic reporting.

Sentinel Lymph Node Biopsy and Management of Regional Lymph Nodes in Melanoma: American Society of Clinical Oncology and Society of Surgical Oncology Clinical Practice Guideline Update

PURPOSE

To update the American Society of Clinical Oncology (ASCO)-Society of Surgical Oncology (SSO) guideline for sentinel lymph node (SLN) biopsy in melanoma.

METHODS

An ASCO-SSO panel was formed, and a systematic review of the literature was conducted regarding SLN biopsy and completion lymph node dissection (CLND) after a positive sentinel node in patients with melanoma.

RESULTS

Nine new observational studies, two systematic reviews and an updated randomized controlled trial (RCT) of SLN biopsy, as well as two randomized controlled trials of CLND after positive SLN biopsy, were included.

RECOMMENDATIONS

Routine SLN biopsy is not recommended for patients with thin melanomas that are T1a (non-ulcerated lesions < 0.8 mm in Breslow thickness). SLN biopsy may be considered for thin melanomas that are T1b (0.8 to 1.0 mm Breslow thickness or <0.8 mm Breslow thickness with ulceration) after a thorough discussion with the patient of the potential benefits and risk of harms associated with the procedure. SLN biopsy is recommended for patients with intermediate-thickness melanomas (T2 or T3; Breslow thickness of >1.0 to 4.0 mm). SLN biopsy may be recommended for patients with thick melanomas (T4; > 4.0 mm in Breslow thickness), after a discussion of the potential benefits and risks of harm. In the case of a positive SLN biopsy, CLND or careful observation are options for patients with low-risk micrometastatic disease, with due consideration of clinicopathological factors. For higher risk patients, careful observation may be considered only after a thorough discussion with patients about the potential risks and benefits of foregoing CLND. Important qualifying statements outlining relevant clinicopathological factors, and details of the reference patient populations are included within the guideline.

Sentinel Lymph Node Biopsy and Management of Regional Lymph Nodes in Melanoma: American Society of Clinical Oncology and Society of Surgical Oncology Clinical Practice Guideline Update

Purpose To update the American Society of Clinical Oncology (ASCO)-Society of Surgical Oncology (SSO) guideline for sentinel lymph node (SLN) biopsy in melanoma. Methods An ASCO-SSO panel was formed, and a systematic review of the literature was conducted regarding SLN biopsy and completion lymph node dissection (CLND) after a positive sentinel node in patients with melanoma. Results Nine new observational studies, two systematic reviews, and an updated randomized controlled trial of SLN biopsy, as well as two randomized controlled trials of CLND after positive SLN biopsy, were included. Recommendations Routine SLN biopsy is not recommended for patients with thin melanomas that are T1a (nonulcerated lesions < 0.8 mm in Breslow thickness). SLN biopsy may be considered for thin melanomas that are T1b (0.8 to 1.0 mm Breslow thickness or < 0.8 mm Breslow thickness with ulceration) after a thorough discussion with the patient of the potential benefits and risk of harms associated with the procedure. SLN biopsy is recommended for patients with intermediate-thickness melanomas (T2 or T3; Breslow thickness of > 1.0 to 4.0 mm). SLN biopsy may be recommended for patients with thick melanomas (T4; > 4.0 mm in Breslow thickness), after a discussion of the potential benefits and risks of harm. In the case of a positive SLN biopsy, CLND or careful observation are options for patients with low-risk micrometastatic disease, with due consideration of clinicopathological factors. For higher-risk patients, careful observation may be considered only after a thorough discussion with patients about the potential risks and benefits of foregoing CLND. Important qualifying statements outlining relevant clinicopathological factors and details of the reference patient populations are included within the guideline. Additional information is available at www.asco.org/melanoma-guidelines and www.asco.org/guidelineswiki .

Presence of immune cells, low tumor proliferation and wild type BRAF mutation status is associated with a favourable clinical outcome in stage III cutaneous melanoma

BACKGROUND

The variable prognosis in stage III cutaneous melanoma is partially due to unknown prognostic factors. Improved prognostic tools are required to define patients with an increased risk of developing metastatic disease who might benefit from adjuvant therapies. The aim was to examine if cellular immune markers in association with tumor proliferation rate and BRAF mutation status have an impact on prognosis in stage III melanoma.

METHODS

We have used two sets of case series with stage III disease: 23 patients with short survival (≤ 13 months) and 19 patients with long survival (≥ 60 months). Lymph node metastases were analyzed for Ki67, CD8 and FOXP3 protein expression using immunohistochemistry. BRAF mutation status was analyzed in a previous study on the same samples.

RESULTS

Low tumor proliferation rate was significantly associated with a better prognosis (p = 0.013). Presence of FOXP3+ T cells was not correlated to adverse clinical outcome. A highly significant trend for a longer survival was found in the presence of an increasing number of markers; CD8+ and FOXP3+ T cells, low tumor proliferation and BRAF wildtype status (p = 0.003). Presence of at least three of these four markers was found to be an independent favorable prognostic factor (OR 19.4, 95% CI 1.9-197, p = 0.012), when adjusting for ulceration and number of lymph node metastases. Proliferation alone remained significant in multivariate analyses (OR 26.1, 95% CI 2.0-344, p = 0.013) but with a wider confidence interval. This panel still remained independent when also adjusting for a previously identified prognostic glycolytic-pigment panel.

CONCLUSIONS

We have demonstrated that presence of immune cells in association with tumor proliferation and BRAF mutation status may further contribute to identify stage III melanoma patients with high risk of relapse.

Regression in primary cutaneous melanoma: etiopathogenesis and clinical significance

Though not required currently for staging, regression is a histopathologic parameter typically reported upon diagnosis of an invasive primary cutaneous melanoma. The studies examining the prognostic significance of regression in patient outcome have yielded controversial findings; likely because the definition and assessment of regression have not been consistent, in addition to subjectivity of pathologists' interpretation. Regression is histologically characterized by variable decrease in the number of melanoma cells accompanied by the presence of a host response consisting of dermal fibrosis, inflammatory infiltrate, melanophages, ectatic blood vessels, epidermal attenuation, and/or apoptosis of keratinocytes or melanocytes; the relative extent of these features depends on the stage of the regression. However, the magnitudes to which these individual changes must be present to meet the threshold of histologic regression have not been well defined or agreed upon, and thus, the definition and classification of histologic regression in melanoma varies considerably among institutions and even among individual pathologists. In order to determine the clinical significance of histologic analysis of regression, there is a compelling need for a universal scheme to objectively define and assess histologic regression in primary cutaneous melanoma, so that the biologic and prognostic significance of this process may be completely understood.Laboratory Investigation advance online publication, 27 February 2017; doi:10.1038/labinvest.2017.8.

Localization of the Sentinel Lymph Node in Melanoma Without Blue Dye

OBJECTIVE

The purpose of this study was to assess regional recurrence rates of patients who underwent sentinel lymph node biopsy (SLNB) using radiocolloid guidance alone.

BACKGROUND

Isosulfan blue dye is commonly used along with Tc99-labeled radiocolloid localization in SLNB for melanoma. Blue dye has, however, been associated with allergic reactions, long-term staining of skin, and increased cost. We hypothesized that the rate of regional recurrence when SLNB is performed with radiocolloid alone would be comparable to established reports using both radiocolloid and blue dye.

METHODS

A prospectively collected database was retrospectively queried for patients who underwent SLNB for melanoma during the years 2005 through 2008. Data collected included patient demographics, primary lesion characteristics, operative details, and recurrence. The primary outcome was the rate of recurrence within the biopsied basin after negative SLNB's performed without isosulfan blue dye.

RESULTS

In 215 patients, 279 nodal basins were identified. All patients underwent successful radiocolloid localization, and positive sentinel nodes were found in 40 patients (18.6%). Six of 175 patients with a negative SLNB developed a regional node recurrence as the first site of metastasis (3.4%). Among all 215 patients, 44 experienced recurrence of any kind (20.5%). Higher mitotic rate and Breslow depth were significantly associated with likelihood of recurrence.

CONCLUSIONS

Success rates, node positivity rates, and rates of regional recurrence after SLNB for melanoma using radiocolloid alone are acceptable and similar to those of prior reports using blue dye plus radiocolloid.

Prediction of survival in patients with thin melanoma: results from a multi-institution study

PURPOSE

Cutaneous melanoma incidence is increasing. Most new cases are thin (≤ 1 mm) with favorable prognoses, but survival is nonetheless variable. Our aim was to investigate new prognostic factors and construct a nomogram for predicting survival in individual patients.

PATIENTS AND METHODS

Data from 2,243 patients with thin melanoma were retrieved from prospectively maintained databases at six centers. Kaplan-Meier survival and crude cumulative incidences of recurrence were estimated, and competing risks were taken into account. Multivariable Cox regression was used to investigate survival predictors.

RESULTS

Median follow-up was 124 months (interquartile range, 106 to 157 months); 12-year overall survival was 85.3% (95% CI, 83.4% to 87.2%). Median times to local, regional, and distant recurrence were 79, 78, and 107 months, respectively. Relapse was significantly related to age, Breslow thickness, mitotic rate (MR), ulceration, lymphovascular invasion (LVI), and regression; incidence was lower and subgroup differences were less marked for distant metastasis than for regional relapse. The worst prognosis categories were age older than 60 years, Breslow thickness more than 0.75 mm, MR ≥ 1, presence of ulceration, presence of LVI, and regression ≥ 50%. Breslow thickness more than 0.75 mm, MR ≥ 1, presence of ulceration, and LVI (all P = .001) were significantly associated with sentinel node positivity. Age, MR, ulceration, LVI, regression, and sentinel node status were independent predictors of survival and were used to construct a nomogram to predict 12-year overall survival. The nomogram was well calibrated and had good discriminative ability (adjusted Harrell C statistic, 0.88).

CONCLUSION

Our findings suggest including LVI and regression as new prognostic factors in the melanoma staging system. The nomogram appears useful for risk stratification in clinical management and for recruiting patients to clinical trials.

The role of sentinel lymph node biopsy for thin cutaneous melanomas of the head and neck

From 18% to 35% of cutaneous melanomas are located in the head and neck, and nearly 70% are thin (Breslow thickness ≤ 1 mm). Sentinel lymph node biopsy (SLNB) has an established role in staging of intermediate-thickness melanomas, however its use in thin melanomas remains controversial. In this article, we review the literature regarding risk factors for occult nodal metastasis in thin cutaneous melanoma of the head and neck (CMHN). Based on the current literature, we recommend SLNB for all lesions with Breslow thickness ≥ 0.75 mm, particularly when accompanied by adverse features including mitotic rate ≥ 1 per mm(2), ulceration, and extensive regression. SLNB should also be strongly considered in younger patients (e.g. < 40 years old), especially in the presence of additional adverse features. All patients who do not proceed with sentinel lymph node biopsy must be carefully followed to monitor for regional relapse.

Impact of the 2009 (7th edition) AJCC melanoma staging system in the classification of thin cutaneous melanomas

CONTEXT

The 7th (2009) edition of the AJCC melanoma staging system incorporates tumor (Breslow) thickness, MR, and ulceration in stratifying T1 primary melanomas. Compared to the prior 6th (2001) edition, MR has replaced CL for thin melanomas.

OBJECTIVE

We sought to identify and report differences of the classification of thin melanomas as well as outcome of SLNB in patients according to the 6th and 7th editions at our institution.

RESULTS

106 patients were identified with thin melanomas verified by wide excision. 31 of 106 thin melanomas were reclassified according to the 7th edition of the AJCC. Of those 31, 15 CL II/III patients (6th edition T1a) were reclassified as T1b based on the presence of mitoses while 16 CL IV patients (6th edition T1b) were categorized as T1a based on the absence of mitoses. 26/31 reclassified patients underwent SLNB, and all were negative. Patients with thin melanoma and a +SLNB (N = 3) were all classified as T1b according to both staging systems.

CONCLUSIONS

In our experience, 29% of thin melanomas were reclassified according to the 7th edition with similar proportions of patients re-distributed as T1a (14%) and T1b (15%). Cases with +SLN corresponded with T1b lesions in both 6th and 7th editions.