<qa>  What is the standard of care at the multicenter site?15. Participation in concurrent therapy protocols of alternative local nodal basin therapies that might confound the analysis of this trial is not permitted. For example, radiation of a non-resected node basin is not acceptable because it might influence outgrowth of residual melanoma in that nodal basin. However, systemic adjuvant therapy or clinical trial adjuvant protocols after the finding of a positive node on LMSL or delayed nodal recurrence in the ultrasound observation arm are both acceptable according to the standard of care at the multicenter site. Patients with positive sentinel nodes or thick primary melanomas who are considered by the multicenter sites investigator as high-risk may receive systemic adjuvant therapy according to the standard practice of that particular site. 