Original articleAnalysis of sentinel lymph node positivity in patients with thin primary melanoma
Section snippets
Methods
This analysis was approved by the institutional review board at the University of California, San Francisco. From 1994 to 2007, patients referred to the University of California, San Francisco/Mount Zion Melanoma Center who had thin melanomas (defined as ≤1.0 mm) and high-risk histologic features were offered SLNB in addition to standard re-excision of the primary site. The following histologic features were recorded and evaluated: Breslow depth, Clark level, ulceration, MR, tumor vascularity,
Results
Table I shows the characteristics of the 484 patients included in our analysis. Of the 484 patients with T1 melanoma, 52.1% were T1a, 40.7% T1b, and 7.2% not classifiable. The mean age of the cohort was 52.2 years, with a mean Breslow depth of 0.80 mm, and a mean follow-up of 4.53 years. The majority of the melanomas were located on the trunk (43.8%), followed by the head and neck (19.6%), lower extremity (19.8%), and upper extremity (16.7%). Ulceration was present in 10.7% of primaries. Of the
Discussion
The revised AJCC staging classification for melanoma now includes MR as a T1b-defining feature (along with ulceration), and has replaced Clark level.17 T1b melanomas have a decreased survival, so a discussion about SLNB may ensue with the patient. In thin melanomas, the prevalence of SLN metastasis has been reported in the range of 0% to 8.3%,10, 18, 19, 20, 21, 22, 23, 24 with T1b lesions accounting for the majority, but certainly not all, SLN-positive cases. Therefore, it is important to
Conclusion
Our analysis identified 4 factors predictive of an increased risk of SLN metastasis. These results highlight the importance of TILs within the primary melanoma as a predictor of SLN status. There is a steady body of evidence showing the importance of TILs for melanoma prognosis at all stages of disease and in the treatment of late-stage melanoma. We propose that TIL level also be included in the synoptic report of all primary melanomas. Data presented in this format can then be studied in a
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Cited by (53)
Predictors of sentinel lymph node positivity in thin melanoma using the National Cancer Database
2019, Journal of the American Academy of DermatologyCitation Excerpt :Our finding that patients <60 years of age with thin melanomas are more likely to have positive SLN are in accordance with a recent study evaluating regional lymph nodes in patients from the NCDB.13 Several other studies have also found an inverse correlation between patient age and SLN positivity.14-18 Male sex was associated with a higher risk of SLN positivity among the NCDB cohort and some previous studies.
Guidelines of care for the management of primary cutaneous melanoma
2019, Journal of the American Academy of DermatologyCitation Excerpt :The WG recommends discussion of SLNB in patients with T1b CM, defined per the eighth edition of the AJCC staging system as less than 0.8 mm with ulceration or 0.8 to 1.0 mm with or without ulceration, although overall rates of SLN positivity in this subset of patients are still relatively low (≤10%). Rates of SLN positivity in T1a CM (<0.8 mm without ulceration) are generally less than 5%.151,152 Therefore, the WG does not recommend SLNB for patients in the T1a subgroup unless other histologic adverse features are evident.2,153,154
Current controversies in early-stage melanoma: Questions on management and surveillance
2019, Journal of the American Academy of DermatologyCitation Excerpt :While the prognosis for patients with early-stage melanoma is excellent, ≤5% of patients with minimally invasive (<0.8 mm) stage I disease will ultimately develop distant metastatic disease,8 and such cases are responsible for the majority of deaths from melanoma.45-47 As a prognostic test, the SLNB identifies patients with a higher risk of death from thin melanoma.48-50 However, SLNB may not be predictive for patients who develop metastasis through hematogenous spread not involving the regional lymph nodes.
Mitotic rate is associated with positive lymph nodes in patients with thin melanomas
2018, Journal of the American Academy of DermatologyCitation Excerpt :Most notably, 1 single-center study of 1764 melanomas did observe a significant association between tumor mitotic rate and overall survival in unadjusted analyses.22 Other studies have failed to observe statistically significant associations between mitotic rate and lymph node positivity among thin melanomas; however, these were likely underpowered, as the largest had only 484 cases.14,23-25 Our study included more than 17,000 patients with thin melanoma who underwent a SLNB and had data on mitotic rate, finding a strong correlation between mitotic rate and lymph node positivity.
Funding sources: None.
Conflicts of interest: None declared.