Clinicopathological predictors of recurrence in nodular and superficial spreading cutaneous melanoma: a multivariate analysis of 214 cases

Nodular melanoma (NM) accounts for most thick melanomas and because of their frequent association with ulceration, fast growth rate and high mitotic rate, contribute substantially to melanoma-related mortality. In a multicentric series of 214 primary melanomas including 96 NM and 118 superficial spreading melanoma (SSM), histopathological features were examined with the aim to identify clinicopathological predictors of recurrence. All consecutive cases of histopathologically diagnosed primary invasive SSM and NM during the period 2005-2010, were retrieved from the 12 participating Italian Melanoma Intergroup (IMI) centers. Each center provided clinico-pathological data such as gender, age at diagnosis, anatomical site, histopathological conventional parameters, date of excision and first melanoma recurrence. Results showed that NM subtype was significantly associated with Breslow thickness (BT) at multivariate analysis: [BT 1.01-2 mm (OR 7.22; 95% CI 2.73-19.05), BT 2.01-4 mm (OR 7.04; 95% CI 2.54-19.56), and BT > 4 mm (OR 51.78; 95% CI 5.65-474.86) (p 5 mitoses/mm (OR 4.87; 95% CI 1.77-13.40) (p = 0.002)]. The risk of recurrence was not significantly associated with NM histotype while BT [BT 1.01-2.00 mm (HR 1.55; 95% CI 0.51-4.71), BT 2.01-4.00 mm (HR 2.42; 95% CI 0.89-6.54), BT > 4.00 mm. (HR 3.13; 95% CI 0.95-10.28) (p = 0.05)], mitotic rate [MR > 2 mitoses/mm (HR 2.34; 95% CI, 1.11-4.97) (p = 0.03)] and the positivity of lymph node sentinel biopsy (SNLB) (HR 2.60; 95% CI 1.19-5.68) (p = 0.007) were significantly associated with an increased risk of recurrence at multivariate analysis. We found that NM subtype was significantly associated with higher BT and MR but it was not a prognostic factor since it did not significantly correlate with melanoma recurrence rate. Conversely, increased BT and MR as well as SNLB positivity were significantly associated with a higher risk of melanoma recurrence.