Odds of positive sentinel node in patients with thin cutaneous melanoma.

Sentinel lymph node biopsy in thin cutaneous melanoma:  A systematic review and meta-analysis.  Cordeiro, Gervaise, Shah, et al.  Ann Surg Oncol.  2016 Mar 1.

Most patients with melanoma have a thin (less than or equal to 1.00 mm) lesion. There is uncertainty as to which patients with thin melanoma should undergo sentinel lymph node (SN) biopsy. We sought to quantify the proportion of SN metastases in patients with thin melanoma and to determine the pooled effect of high-risk features of the primary lesion on SN positivity.

Published literature between 1980 and 2015 was searched and critically appraised. Primary outcome was the proportion of SN metastases in patients with thin cutaneous melanoma. Secondary outcomes included the effect of high-risk pathological features of the primary lesion on the proportion of SN metastases. Summary measures were estimated by Mantel-Haenszel method using random effects meta-analyses.

Sixty studies (10,928 patients) met the criteria for inclusion. Pooled SN positivity was 4.5 %. Predictors of a positive SN were: thickness greater than/equal to 0.75 mm; with a likelihood of SN metastases of 8.8%; Clark level IV/V; with a likelihood of 7.3%; greater than/equal to 1 mitoses/mm²; pooled likelihood 8.8%; and the presence of microsatellites; likelihood 26.6%.

The pooled proportion of SN metastases in thin melanoma is 4.5 %. Thickness greater than/equal to 0.75 mm, Clark level IV/V, mitoses, and microsatellites significantly increased the odds of SN positivity and should prompt strong consideration of SN biopsy.

I really can think of no reasonable argument to guesstimate  on this one.  Taking out the sentinel node when completing the needed wide excision after a melanoma lesion seems like a no-brainer to me.  Once the sentinel node is analyzed....you will KNOW what you are dealing with.  What to do after that is a bit more murky.  - c