J Neurol Surg B Skull Base
DOI: 10.1055/a-2437-7837
Original Article

Sinonasal Mucosal Melanoma Survival Outcomes, Recurrence Patterns, and Prognostic Factors: A Systematic Literature Review and Meta-analysis of Publications after 2000

1   Department of Otolaryngology, The Ohio State University College of Medicine, Columbus, Ohio, United States
2   Department of Otolaryngology–Head and Neck Surgery, University of Missouri, Columbia, Missouri, United States
,
3   Department of Otolaryngology–Head and Neck Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
4   Department of Otolaryngology–Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States
,
Ricardo L. Carrau
3   Department of Otolaryngology–Head and Neck Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
,
Kyle VanKoevering
3   Department of Otolaryngology–Head and Neck Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
› Author Affiliations
 

Abstract

Background Sinonasal mucosal melanoma (SNMM) comprises <1% of all head and neck cancers but has one of the highest 5-year mortalities.

Methods A systematic review and analysis using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta- Analyses) guidelines was conducted on SNMM survival, recurrence, and prognostic factors.

Results A total of 2,379 abstracts were reviewed resulting in 90 studies describing 3347 SNMM patients. Patients were 49.65% male and 66.5 years old. Surgery plus radiation therapy, followed by surgery only, then radiation only were the most common treatments. Chemotherapy and immunotherapy were used in 418 patients and 101 respectively. The 2-, 3-, and 5-year overall survivals are 55.97, 40.09, and 30.35%, respectively. The 5-year disease-free survival and disease-specific survival are 25.56 and 38.04%. The 5-year local, regional, and distant recurrence-free survivals are 42.35, 81.64, and 44.65%. Mean survival after diagnosis was 26.99 months. Local (n = 650), regional (n = 226), and distant (n = 723) failure presented after 19.36, 6.35, and 12.42 months. Sites of metastasis were lung, liver, bone, brain, skin, kidney, and adrenal glands. Distant metastases, disease in the paranasal sinuses, and higher stage were noted to have worse survival outcomes. Positive margins did not significantly impact overall survival in 11/12 studies.

Conclusion Overall survival over 20 years has remained poor with 70% of patients deceased in 5 years. About half of patients will develop distant failure and will thereafter rapidly decline. These data indicate need for advances in treatment of SNMM and new efforts with targeted immunotherapy offer a promising avenue toward improving survival outcomes.


Introduction

Mucosal melanoma is a rare and aggressive subvariant of melanoma affecting mucosal melanocytes in the head and neck, genitals, and digestive tract. With an annual incidence of 2.2 cases per million,[1] mucosal melanoma comprises less than 1% of head and neck malignancies.[2] Unlike cutaneous melanoma, mucosal melanoma does not have clear risk factors, disease course, or treatment recommendations.[3] [4] [5] [6] [7] [8] Even the purpose of the mucosal melanocyte is debated.[3] Although mucosal melanocytes contain the characteristic melanin pigment, they do not receive UV light exposure and do not serve to protect against UV radiation like their cutaneous counterparts. Literature has found that melanocytes in general may play a role in the innate and acquired immune system, so it is hypothesized that immune defense may be the primary purpose of the mucosal melanocytes.[9] [10] [11]

Within the head and neck, mucosal melanoma most commonly presents in the sinonasal region.[2] Compared with other sinonasal malignancies, however, mucosal melanoma still only comprises about 4% of tumors and is uncommon enough that epidemiological studies cannot fully analyze it.[3] [12] In addition to its rarity, sinonasal mucosal melanoma (SNMM) often presents with insidious and nonspecific symptoms. Most patients diagnosed with SNMM are asymptomatic; however, they may present with nasal obstruction, epistaxis, and/or cranial neuropathies stemming from compression of the orbit or skull base.[13] On exam, these lesions present with a variety of pigmentation ranging from amelanotic and fleshy to full brown to black pigmentation.[8] [14]

Due to its rarity, most literature on this disease comes from small case series and 5-year overall survival (OS) has been reported in the range from 0 to 61.5%.[8] [14] Some larger databases such as SEER (Surveillance, Epidemiology, and End Results)[15] and the National Cancer Database[16] contain more accurate survival information on SNMM but lack information on recurrence, one of the most challenging aspects of the disease. This study aimed to systematically review recent existing literature on SNMM to analyze outcomes, survival, recurrence patterns, and prognostic factors.


Methods

This study was conducted using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta- Analyses) guidelines.[17] Three electronic databases (PubMed, Web of Science, and Science Direct) with an identical series of keywords were queried, and the results were collected directly into an electronic literature organization system (Endnote Online). Search entries were as follows: sinonasal mucosal melanoma; sinonasal mucosal melanoma AND Recurrence; sinonasal mucous melanoma AND Recurrence; sinus AND mucosal melanoma AND recurrence; nose AND mucosal melanoma AND recurrence; sinus AND mucosal melanoma AND follow up; nose AND mucosal melanoma AND follow up; sinonasal mucosal melanoma AND follow up; upper airway AND mucosal melanoma. After resulting literature was collected from the three electronic databases into Endnote (Clarivate, Jersey), an initial phase of removing duplicate papers was achieved using a duplicate identifying function of Endnote.

Inclusion and Exclusion Criteria

Study inclusion criteria were (1) full English text available, (2) published in the year 2000 or later, (3) included survival or recurrence data on two or more cases of biopsy-proven SNMM, and (4) cases were not reported in a database or other case series already used in the study. Articles were excluded if they did not report separate statistical analyses of SNMM as opposed to combining sinonasal and oral mucosal melanoma. In cases where one author published multiple articles with patient data from overlapping years, data were extracted from the study that reported a statistic with the largest n value to ensure that there were no duplicate patients included in this study's results.


Screening

After initial duplicates were removed automatically, the remaining literature underwent title and abstract review by the primary author. Papers were included for further screening if they reported multiple cases of mucosal melanoma of the head and neck and had a full English text available. The included literature was then sorted alphabetically by first author and full texts were assessed for eligibility. During this stage, remaining duplicate entries not detected by the automatic removal process were individually removed from the inclusion cohort.


Data Extraction

For each included study, data were extracted into a standardized form. Patient demographics, tumor characteristics (2009 TNM stage, site of origin, pigmentation, and margin status), treatment modalities, prognostic factors, recurrence data (number of patients with recurrences, site of recurrence, time until recurrence, and treatment of recurrence), and survival outcomes (2, 3, and 5-year OS, disease-free survival, disease-specific survival, and median survival after diagnosis) were collected. Comparative statistics and regression analysis findings analyzing patient survival outcomes were recorded if available. The year of publication, SNMM sample size, institutions contributing data, data collection period, and study design were noted for each included study.


Statistical Analysis

Statistics were calculated using SPSS Version 28.[18] Results were concluded using calculations weighted by each paper's sample size. To determine the average age of patients at diagnosis, the reported median age of each cohort was weighted by the sample size of the original study and then averaged among the included studies. If the median was not reported, the mean was used in its place. This technique was also used for the calculation of time from diagnosis until recurrence, time from diagnosis until death, and time from recurrence until death.



Results

The electronic database search produced 4,819 results between Web of Science, PubMed, and Science Direct. After duplicates were removed, 2,379 results remained for title and abstract screening. A total of 633 full texts were included to review after initial title and abstract screening. When these full texts were analyzed for inclusion criteria, 90 studies met the requirements for data extraction ([Fig. 1]).[7] [8] [13] [14] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] [64] [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] [76] [77] [78] [79] [80] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [98] [99] [100] [101] [102] [103] [104]

Zoom
Fig. 1 PRISMA schematic describing literature review and screening process. PRISMA. Preferred Reporting Items for Systematic Reviews and Meta- Analyses.

Included studies were conducted in 28 different countries with the United States being the most common. Years of publication ranged from 2000 to 2022 with a mode of 2017. Eighty-three studies were retrospective chart reviews, six were case series, and one was a database limited to one country. The average number of patients per paper was 40 patients (range: 2–221, standard deviation [SD]: 43.4).

There were 3,347 patients included in this study. A total of 2,635 patients were included in recurrence analysis and 3,213 patients were included in prognostic factor analysis. Patients were 49.65% male with a mean age of 66.53 years old at diagnosis. A total of 759 (22.9%) of patients were treated in the United States. Treatment information was recorded for 2,731 patients. Of those patients, 2,034 (74.5%) were recorded to have undergone resection. When specified, the most common treatment plan was surgery plus radiation therapy (n = 824), followed by surgery only (n = 453), then radiation only (n = 104). A total of 52.2% of surgeries had an open component, whereas 47.79% were endoscopic only (n = 602 and 551, respectively). The surgical approach was not specified in 881 patients. Chemotherapy was used in 418 patients and 101 were treated with immunotherapy. Immunotherapy was most commonly used in patients who presented with recurrent disease or those who presented initially with distant metastases. A total of 111 patients were treated with palliative intent.

Survival Outcomes

The average 2-, 3-, and 5-year OS are 55.97, 40.09, and 30.35%, respectively. The 5-year disease-free survival and disease-specific survival are 25.56 and 38.04%. The 5-year local, regional, and distant recurrence-free survivals are 42.35, 81.64, and 44.65%. The weighted average survival after diagnosis was 26.99 months. Patients treated in the United States had statistically higher 5-year OS compared with those treated elsewhere (t(2116) = 8.323, p < 0.001, U.S. avg = 33.39 (10.49), other country average = 28.85 (11.79)).


Recurrence

Local (n = 650), regional (n = 226), and distant (n = 723) failure presented after 19.36, 6.35, and 12.42 months, respectively, after first curative treatment. After local recurrence, patients died after 10.5 months on average; however, only one paper reported that statistic. Patients died 4.15 months after distant metastasis on average. Average time from any recurrence until death was 50.9 months. The most to least common sites of metastasis specified were lung, liver, bone, brain, kidney, and adrenal glands (n = 91, 75, 53, 29, 6, and 4). There were 30 distant metastases that traveled to sites not specified.


Prognostic Factors

The prognostic findings within the literature review are described in [Table 1]. Patients with distant metastases, disease in the paranasal sinuses, and higher stage were noted in multiple studies (6, 10, and 15, respectively) to have a statistically significant worse survival outcome. Positive margins after resection were not a significant factor in OS in 11 out of 12 studies, which analyzed it. Nine studies compared endoscopic versus open approaches with six finding no difference in outcomes between approaches and three finding that endoscopic approaches have statistically better outcomes. Adjuvant radiation was analyzed in 17 studies with 15 finding no difference in patient outcomes, 1 finding better patient outcomes, and 1 study finding worse patient outcomes with adjuvant radiation. Immunotherapy use was evaluated in three studies. It was found to be associated with increased survival in one study with the remaining two finding no difference in survival.

Table 1

Collection of studies that analyze prognostic factors of sinonasal mucosal melanoma with associated statistical results

Author

Year

n

Variables without survival significance

Variables with survival significance

Statical findings

Almutuawa

2020

20

Age, gender, ethnicity, smoking history, AJCC staging (7th edition), margin status, adjuvant RT, bone invasion, ulceration, periorbital involvement, recurrence

Multivariate hazard ratio (HR) (95% CI)

Open resection vs. endoscopic resection

19.93 (2.14–185.4), p = 0.009

Lymphatic invasion

0.05 (0.004–0.7), p = 0.031

Amit

2018

198

Sex, age, T3 vs. T4a, nodal metastasis, margin status, local invasion, mitoses > 1, ulceration, tumor thickness, bone invasion, adjuvant RT, adjuvant CT

Univariate HR (95% CI)

Paranasal vs. nasal

1.95 (1.25-2.94), p = 0.003

Pathologic T stage T4b vs. T3

2.02 (1.14-3.4), p = 0.04

Distant metastasis

4.01 (1.93-7.49), p = 0.0006

Bachar

2008

49

Sex, tumor site, stage, margin status, and adjuvant RT, adjuvant CRT

Univariate log-rank test

Age > 50 at diagnosis (worse survival)

p = 0.02

Cao

2017

33

Open vs. endoscopic resection

Univariate log-rank test

Caspers

2017

51

Age, sex, tumor site, involved sinuses, endoscopic vs. open surgery, adjuvant RT, radiation dose, local recurrence, nodal metastasis

Univariate HR (95% CI)

High Adult Comorbidity Evaluation-27 Score

5.02 (1.17-21.6), p = 0.03

AJCC 7th edition tumor stage 4 vs. 3

2.34 (1.09-5.02), p = 0.03

Positive margins

3.27 (1.23-8.68), p = 0.02

Distant metastasis

2.50 (1.14-5.45), p = 0.02

Multivariate HR (95% CI)

Positive margins

p = 0.048

Cheng

2007

23

Gender, margin status

Univariate log-rank test

Nasal cavity vs. paranasal sinus (paranasal worse)

p = 0.001

Distant metastasis

p < 0.001

Çomoğlu

2018

21

Treatment modality, nodal metastasis, margin status, location of disease, age

Univariate log-rank test

Mitotic activity (worse with higher activity)

p = 0.037

Dauer

2008

61

Presence of melanin, necrosis, nuclear pleomorphism, histological subtype, depth of invasion, and ulceration

Univariate Cox relative risk, RR (95% CI)

Nonseptum location

2.7 (1.3–5.6), p = 0.01

Maxillary sinus origin

2.3 (1.2–4.3), p = 0.01

Tumor size

1.5 (1.1–1.9), p = 0.003

Dréno

2017

44

Age, gender, use of RT, use of CT, use of IT

Univariate log-rank test

Headache, facial pain, and V2 anesthesia

p = 0.02

Origin in sinus vs. nasal cavity

p = 0.03

AJCC 6th edition T3-4 vs. T1-2

p = 0.003

AJCC 7th edition T4 vs. T3

p = 0.006

Fuji

2014

20

T stage, use of concurrent CT, FDG-PET signal level, and tumor size

Univariate log-rank test

Undifferentiated morphology

p = 0.018

Göde

2017

17

Tumor origin, regional metastases, tumor size, T stage, number of mitoses, staining positive for Melan A, S100, HMB-45, presence of necrosis or C-KIT positivity

Cox regression analysis

Gras-Cabrerizo

2015

20

Tumor origin

Univariate log-rank test

Advanced Thompson stage

p = 0.006

AJCC 7th edition TNM stage for SMM

p = 0.05

AJCC 7th edition TNM stage for sinonasal carcinoma

p = 0.006

Jangard

2012

186

Type of primary treatment

Univariate log-rank test

Male sex

p = 0.038

Age > 60

p = 0.040

Epistaxis vs. nasal congestion only

p = 0.046

Kanetaka

2011

13

Lymphokine-activated killer (LAK) cell therapy use, margin status

Univariate log-rank test

Kerr

2011

17

Tumor microvascular density

Cox regression analysis

Khademi

2011

18

Age, sex, total dose of radiotherapy, size of primary tumor

Univariate HR (95% CI)

Common basic stage

5.79 (1.65–20.41), p = 0.006

Initial complete response to treatment

13.41 (1.57–114.92), p = 0.018

Multivariate HR (95% CI)

Common basic stage

22.17 (1.66–296.06), p = 0.019

Koivunen

2012

50

Primary tumor location, involvement of palate, frontal sinus, nasopharynx, infraorbit

Multivariate log-rank test

AJCC 7th edition T stage

p = 0.01

Involvement of sphenoid sinus

p = 0.01

Lai

2019

92

Surgery plus RT vs. surgery plus CRT

Univariate log-rank test

Surgery alone vs. surgery plus RT

p = 0.003

Surgery alone vs. surgery plus CRT

p = 0.002

Ledderose

2022

27

Tumor-infiltrating lymphocyte score (worse with less lymphocytes)

Univariate log-rank test

p < 0.05

Lund

2012

115

Adjuvant RT, sex, age, tumor site

Mantel– Cox proportional hazard test

Positive lymph nodes at diagnosis

p < 0.001

Endoscopic vs. open approach

p = 0.013

Lundberg

2019

58

Gender, endoscopic vs. open surgery, adjuvant RT

Univariate log-rank test

Age > 70

p = 0.036

Sinus vs. nasal cavity origin

p = 0.038

7th UICC stage IV vs. III

p = 0.003

T4 vs. T3 tumors

p = 0.006

Positive lymph nodes at diagnosis

p < 0.001

Manton

2019

31

Age, gender, primary site, smoking history, use of RT, margin status, time from diagnosis to surgery

Cox's proportional hazard ratio

Stage IVB vs. III

3.87 (1.02, 14.74), p = 0.047

Martin

2004

20

Age, gender, melanosis, site involved, radiotherapy dose, or fraction size

Cox's proportional hazard ratio

UICC 6th edition T stage 3 or 4

4.3 (1.1 − 6.1), p < 0.05

Meerwein

2019

34

Use of IT, T stage

Univariate log-rank test

Residual disease

p < 0.001

Michel

2013

35

Depth of invasion

Univariate log-rank test

Distant metastasis

p = 0.032

7th edition AJCC SMM stage IVb or IVc

p = 0.012

AJCC 7th edition TNM stage for sinonasal carcinoma T3–4 vs. T1–2

p = 0.012

Miglani

2017

22

Endoscopic vs. open approach

Univariate log-rank test

Treatment with curative intent

p = 0.042

Mochel

2015

32

Margin status, T stage, in situ vs. invasion, histological presentation, ulceration, nodal metastasis, mitotic figures, intraepithelial melanocytic proliferation

Univariate log-rank test

Tumor necrosis

p = 0.04

Mohr

2016

18

Completeness of resection

Univariate log-rank test

Moya-Plana

2019

68

Univariate log-rank test

Paranasal vs. nasal

p < 0.001

Nakaya

2004

16

Margin status

Univariate log-rank test

Samstein

2017

78

Age, use of RT, gender, margin status, resection status

Multivariate HR

Sinus vs. nasal cavity origin

3.41, p < 0.05

AJCC 7th edition T stage (higher stage worse)

0.43, p < 0.05

Post-RT PET standard uptake value < 4

0.24, p < 0.05

Shi

2010

33

Peritumoral tumor-associated macrophages density

Intratumor tumor-associated macrophages density (higher density worse)

Univariate log-rank test

p = 0.036

Soares

2018

31

Age, gender, use of adjuvant therapy, tumor origin, mitotic rate, vascular invasion, neural invasion, cell morphology

Multivariate HR (95% CI)

AJCC 7th edition stage IV vs. III

7.351 (1.392–38.821), p = 0.019

High expression of p-Akt1

65.726 (6.491–665.549), p < 0.001

Sun

2014

65

Adjuvant RT, sex, primary tumor site, cTNM classification, CT

Multivariate HR (95% CI)

Distant metastasis

4.428 (1.453–13.495), p = 0.009

Surgery vs. no surgery

0.445 (0.235–0.842), p = 0.013

Use of biotherapy

0.495 (0.260–0.943), p = 0.032

Swegal

2013

25

Open vs. endoscopic resection

Univariate log-rank test

Tajudeen

2014

14

Sex, treatment modality, AJCC T stage

Univariate log-rank test

Perineural or lymphovascular invasion

p = 0.021

Thariat

2011

25

Age

Univariate HR (95% CI)

En bloc resection

6.4 (1.6–25.0), p = 0.003

Local control

3.4 (1.0–11.9), p = 0.044

Thompson

2003

115

Geographic location with respect to 40 degrees N latitude, duration of symptoms, tumor thickness, presence of fibrosis, tumor necrosis, use of adjuvant therapy

Univariate log-rank test

Obstruction only vs. epistaxis

p = 0.02

Nasopharynx tumors

p < 0.001

Tumor > 3 cm

p = 0.005

Undifferentiated morphology

p = 0.033

>10 mitotic figures per 10 HPFs

p = 0.026

Disease recurrence

p < 0.001

Age > 60

p = 0.029

Vandenhende

2011

17

Margin status, adjuvant RT, open vs. endoscopic approach, tumor location

Univariate log-rank test

Wang

2020

35

Age, gender, MRI features, CT enhancement

Univariate log-rank test

Paranasal vs. nasal

p = 0.04

Post operative RT (worse prognosis with RT)

p = 0.02

AJCC 7th edition T4 vs. T3 tumors

p = 0.02

Wang

2022

117

Sex, age, side, location, size, histological type, melanin particles, nuclear fission, tumor-infiltrating lymphocytes, PD-L1 expression

Univariate log-rank test

AJCC 7th edition T stage

p < 0.05

Won

2015

155

Age, smoking, tumor size, morphology, presence of skip lesions, pigmentation, AJCC 7th edition T stage, AJCC 7th edition TNM stage, local recurrence, nodal recurrence, use of neck dissection, adjuvant RT, adjuvant CT, adjuvant CRT

Multivariate Cox regression, HR (95% CI)

Male sex

2.053 (1.222–3.448), p = 0.007

Sinus vs. nasal cavity origin

1.832 (1.102–3.044), p = 0.020

Distant metastasis

1.783 (1.054–2.925), p = 0.035

Open resection vs. endoscopic resection

1.702 (1.007–2.875), p = 0.047

Yin

2019

54

Expression of CD45, CD3, CD8, CD4, CD20, CD56, or CD68, age, sex, site, pigmentation

Multivariate HR (95% CI)

Progression of disease

12.365 (2.290–66.779), p = 0.003

Postoperative CT

0.204 (0.045–0.924), p = 0.039

AJCC 8th edition stage

0.066 (0.007–0.615), p = 0.048

Zhu

2018

64

CD44 expression

Multivariate HR

HER4 expression (worse prognosis)

3.51, p < 0.05

Abbreviations: AJCC, American Joint Committee on Cancer; CI, confidence interval; CRT, chemoradiography; CT, computed tomography; FDG-PET, fluorodeoxyglucose–positron emission tomography; MRI, magnetic resonance imaging; RT, radiotherapy; TNM, Tumour, Node, Metastasis; UICC, Union for International Cancer Control.



Immunotherapy

There were nine studies[30] [36] [46] [61] [63] [65] [66] [77] [88] that reported isolated survival data on patients who received immunotherapy. In total, 51 patients who received immunotherapy were included in this subanalysis. The 5-year OS for these patients was 38.36%. The average time until progression for these patients was 15.8 months (n = 17, SD = 10.1). There was a wide variety of treatment regiments including ipilimumab alone (n = 7), pembrolizumab alone (n = 3), ipilimumab plus pembrolizumab (n = 2), pembrolizumab plus nivolumab (n = 3), vemurafenib (n = 1), interferon alpha (n = 14), interleukin-2 (n = 9), and the Bacillus Calmette–Guérin (BCG) vaccine (n = 10). Interferon alpha, interleukin -2, and BCG vaccine therapy was used in an adjuvant regimen (n = 33/33), whereas pembrolizumab, nivolumab, ipilimumab, and vemurafenib were mostly used in a salvage setting (n = 13/16 salvage, 2/16 adjuvant, and 1/16 neoadjuvant). There were three studies that evaluated the prognostic value of immunotherapy. One study found better prognosis with immunotherapy treatment,[88] and two found no difference.[36] [66]



Discussion

This study is the largest to date that collectively analyzes and reports survival outcomes, recurrence patterns, and prognostic factors of SNMM. Survival and disease outcomes remain poor for this disease, with a 5-year OS rate of 30.35% and a 5-year disease-free survival of 25.56%. SNMM has a propensity for recurrence with most occurring distantly. Distant metastasis is most likely to be seen in the lungs, liver, bone, and brain, highlighting the importance of obtaining serial brain imaging in addition to positron emission tomography scans. Worse outcomes are seen in tumors that are a higher stage, are in the paranasal sinuses, and present with distant metastases. Of note, survival was found to be better in the United States compared with other countries included in this analysis. No additional factor was able to be isolated between these groups to explain this finding. This suggests that there may be underlying exposure, population, or structural healthcare variable such as access to care or likelihood of incidental discovery that may be contributing to this difference.

Several treatment strategies have been employed with mixed results including endoscopic versus surgical resection, en bloc versus piecemeal resection, radiation, chemotherapy, and immunotherapy use. The most popular treatment approach utilized was surgical resection with adjuvant radiation. Interestingly, while surgical treatment was heavily associated with increased survival, margin status after surgical treatment was not found to be a significant predictor of survival in all but one study that explored it. Studies have suggested that mucosal melanoma expresses a unique pathway of hematological spread,[78] so perhaps at the time of surgery, the malignancy has already seeded the blood making margin status of less consequence.

Systemic treatment modalities such as chemotherapy[100] and, more recently, immunotherapy[88] have demonstrated some association with improved survival and is a promising area of active exploration.[105] [106] The emergence of immunotherapy was first discussed within the realm of SNMM in the mid-2000s.[107] While it has mostly been used as a salvage or adjuvant treatment, some authors have suggested there may be a role for immunotherapy in the initial treatment regimen.[108] Additionally, we identified and analyzed three studies that evaluated immunotherapy as a prognostic factor in SNMM. Dréno et al evaluated 5-year OS in mucosal melanoma patients who received interferon alpha therapy and found there was no difference in survival compared with patients who did not receive that therapy. Meerwein et al evaluated monoclonal antibody immunotherapies in the setting of SNMM and concluded that there was no difference in OS, however, did find that these therapies offered an opportunity for increased progression-free survival in the salvage setting. Particularly, combination therapy such as ipilimumab plus pembrolizumab or ipilimumab plus nivolumab demonstrated the best results with progression-free survival up to 16 months in their sample. Sun et al explored the role of biotherapies, including BCG vaccine prior to 1998 and interferon-alpha versus interleukin-2 therapy after 1998 and found that there was borderline statistical significance for improved OS in patients receiving one of these therapies in the adjuvant therapies (5-yr OS 50.9%, p = 0.076). However, upon multivariate analysis, they found that use of biotherapy was independently a predictor of improved survival, (hazard ratio = 0.495, 95% confidence interval: 0.260–0.943, p < 0.05).

Recurrence of this disease proves to be the most challenging aspect in successful treatment. The propensity for distant and local recurrence contributes to the low survival rates. SNMM is not as likely to recur at regional lymph nodes; however, when SNMM does recur into the lymph nodes, its spread occurred twice as fast as distant recurrence and three times as fast as local recurrence. Nodal metastases outcomes demonstrated a mixed impact on prognosis, but multiple studies did show worse survival outcomes with nodal metastases[60] or higher TNM stage.[41] [48] [100] This could suggest that patients with nodal metastases present with more aggressive disease in turn warrant more aggressive treatment both locally and systemically. Given that this disease does not respect margin status, systemic treatment is likely to play a key role in disease control; however, more research is needed to support this hypothesis given the limited availability of data.

The authors acknowledge that there were several limitations of this study including reporting bias, the potential for outdated data, and grouped statistical analysis. As a systematic literature review depends upon the caliber of previously published data, it must be discussed that up to 75% of otolaryngology publications demonstrating risk for bias.[109] In particular, outcome reporting bias may be problematic, particularly in the setting of a disease that has a relatively low OS. While bias is inescapable, the authors believe that data presented in the current study provide valuable insights on a rare disease entity. Additionally, the authors limited inclusion criteria to only literature published in the year 2000 or later as to try to limit the use of outdated cases; however, some studies presented the entire cohort of SNMM experienced at a single institution that include more historic cases. Lastly, our statistical methods aimed to properly weigh and combine reported data. The median was chosen to decrease the impact of outliers; however, this was not possible for all included studies. In some cases, the mean was utilized when the median was not available. The authors felt like the inclusion of means was favorable to using median data only as to consider the highest number of cases. If assuming that data are normally distributed, the mean and median of a dataset should be approximately equal.


Conclusion

In conclusion, this meta-analysis serves as the largest study of SNMM and includes 3,347 patients. OS for SNMM remains poor with a 5-year OS of 30.35%. SNMM recurs in over 50% of patients with the most common sites of recurrence being local and distant metastases to the lung, liver, and bone. More research is needed to identify further treatment strategies toward SNMM; however, this study found the most common approach to treatment to be combined surgery and adjuvant radiation. The role of immunotherapy shows promise to play a larger role in the treatment of SNMM in the future with the aim of improving survival.



Conflict of Interest

None declared.


Address for correspondence

Annie J. Orr, MD
Department of Otolaryngology–Head and Neck Surgery, University of Missouri School of Medicine
1 Hospital Dr MA314, Columbia, MO 65201
United States   

Publication History

Received: 04 August 2024

Accepted: 07 October 2024

Accepted Manuscript online:
09 October 2024

Article published online:
05 November 2024

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Fig. 1 PRISMA schematic describing literature review and screening process. PRISMA. Preferred Reporting Items for Systematic Reviews and Meta- Analyses.