The Clinicopathological and Gene Expression Profile (CP‐GEP) model was developed to accurately identify patients with T1-T3 primary cutaneous melanoma at low risk for nodal metastasis.,To validate the CP‐GEP model in an independent Dutch cohort of patients with melanoma.,Patients (aged ≥ 18 years) with primary cutaneous melanoma who underwent sentinel lymph node biopsy (SLNB) between 2007 and 2017 at the Erasmus Medical Centre Cancer Institute were eligible.,The CP‐GEP model combines clinicopathological features (age and Breslow thickness) with the expression of eight target genes involved in melanoma metastasis (ITGB3, PLAT, SERPINE2, GDF15, TGFBR1, LOXL4, CXCL8 and MLANA).,Using the pathology result of SLNB as the gold standard, performance measures of the CP‐GEP model were calculated, resulting in CP‐GEP high risk or low risk for nodal metastasis.,In total, 210 patients were included in the study.,Most patients presented with T2 (n = 94, 45%) or T3 (n = 70, 33%) melanoma.,Of all patients, 27% (n = 56) had a positive SLNB, with nodal metastasis in 0%, 30%, 54% and 16% of patients with T1, T2, T3 and T4 melanoma, respectively.,Overall, the CP‐GEP model had a negative predictive value (NPV) of 90·5% [95% confidence interval (CI) 77·9-96.2], with an NPV of 100% (95% CI 72·2-100) in T1, 89·3% (95% CI 72·8-96·3) in T2 and 75·0% (95% CI 30·1-95·4) in T3 melanomas.,The CP‐GEP indicated high risk in all T4 melanomas.,The CP‐GEP model is a noninvasive and validated tool that accurately identified patients with primary cutaneous melanoma at low risk for nodal metastasis.,In this validation cohort, the CP‐GEP model has shown the potential to reduce SLNB procedures in patients with melanoma.,What is already known about this topic?,The majority (70-85%) of patients with cutaneous melanoma who undergo a sentinel lymph node biopsy (SLNB) procedure have no metastasis in the SLN.To identify patients at low risk for nodal metastasis, the Clinicopathological and Gene Expression Profile (CP‐GEP) model was developed (n = 754 patients, US cohort).,The CP‐GEP model combines age, Breslow thickness and the expression of eight target genes involved in melanoma metastasis, and has the potential to reduce SLNB procedures in patients with T1-T3 cutaneous melanoma.,The majority (70-85%) of patients with cutaneous melanoma who undergo a sentinel lymph node biopsy (SLNB) procedure have no metastasis in the SLN.,To identify patients at low risk for nodal metastasis, the Clinicopathological and Gene Expression Profile (CP‐GEP) model was developed (n = 754 patients, US cohort).,The CP‐GEP model combines age, Breslow thickness and the expression of eight target genes involved in melanoma metastasis, and has the potential to reduce SLNB procedures in patients with T1-T3 cutaneous melanoma.,What does this study add?,This is the first independent validation of the CP‐GEP model in European patients with primary cutaneous melanoma.The CP‐GEP model can be applied to full‐excision tumour tissue and does not require macrodissection of tumour tissue.The CP‐GEP model has a negative predictive value of 90·5% (95% confidence interval 77·9-96·2) in T1-T3 melanomas.The CP‐GEP model is a promising tool in patient care.,In this validation cohort, the CP‐GEP model has shown the potential to reduce SLNB procedures in patients with primary cutaneous melanoma.,This is the first independent validation of the CP‐GEP model in European patients with primary cutaneous melanoma.,The CP‐GEP model can be applied to full‐excision tumour tissue and does not require macrodissection of tumour tissue.,The CP‐GEP model has a negative predictive value of 90·5% (95% confidence interval 77·9-96·2) in T1-T3 melanomas.,The CP‐GEP model is a promising tool in patient care.,In this validation cohort, the CP‐GEP model has shown the potential to reduce SLNB procedures in patients with primary cutaneous melanoma.
Mitotic rate is no longer considered a staging criterion for thin melanoma in the 8th edition of the American Joint Committee on Cancer Staging Manual.,The aim of this observational study was to identify prognostic factors for thin melanoma and predictors and prognostic significance of sentinel lymph node (SLN) involvement in a large multicenter cohort of patients with melanoma from nine tertiary care hospitals.,A total of 4249 consecutive patients with thin melanoma diagnosed from January 1, 1998 to December 31, 2016 were included.,The main outcomes were disease‐free interval and melanoma‐specific survival for the overall population and predictors of SLN metastasis (n = 1083).,Associations between survival and SLN status and different clinical and pathologic variables (sex, age, tumor location, mitosis, ulceration, regression, lymphovascular invasion, histologic subtype, Clark level, and Breslow thickness) were analyzed by Cox proportional hazards regression and logistic regression.,SLN status was the most important prognostic factor for melanoma‐specific survival (hazard ratio, 13.8; 95% CI, 6.1‐31.2; P < 0.001), followed by sex, ulceration, and Clark level for patients who underwent SLNB.,A mitotic rate of >2 mitoses/mm2 was the only factor associated with a positive SLN biopsy (odds ratio, 2.9; 95% CI, 1.22‐7; P = 0.01.,SLN status is the most important prognostic factor in thin melanoma.,A high mitotic rate is associated with metastatic SLN involvement.,SLN biopsy should be discussed and recommended in patients with thin melanoma and a high mitotic rate.