Note: Some citations in the text of this section are followed by a level of evidence. The PDQ editorial boards use a formal ranking system to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. (Refer to the PDQ summary on Levels of Evidence for more information.)

Stage II melanoma is defined by the following clinical stage groupings:

• T2b, N0, M0
• T3a, N0, M0
• T3b, N0, M0
• T4a, N0, M0
• T4b, N0, M0

STANDARD TREATMENT OPTIONS:

• Current evidence suggests that for melanomas with a thickness between 2 mm and 4 mm, the surgical margins need to be 2 cm or less. The Intergroup Melanoma Surgical Trial compared 2-cm versus 4-cm margins for patients with 1-mm to 4-mm thick melanomas. With a median follow-up of more than 10 years, no significant difference was observed between the two groups in terms of local recurrence or survival. The reduction in margins from 4 cm to 2 cm was associated with a statistically significant reduction in the need for skin grafting (from 46% to 11%; P < .001) and a reduction in the length of the hospital stay.[1] Depending on the location of the melanoma, most patients can now have this surgery performed on an outpatient basis. A study conducted in the United Kingdom randomly assigned patients with melanomas more than 2 mm thick to excision with either 1-cm or 3-cm margins.[2] Patients treated with 1-cm margins of excision had a higher rate of local regional recurrence (hazard ratio [HR] = 1.26; 95% confidence interval [CI], 1.00–1.59; P = .05), but no difference in survival was seen (HR = 1.24; 95% CI, 0.96–1.61; P = .1). This suggests that 1-cm margins may not be adequate for patients with melanomas more than 2 mm thick. Few data are available to guide treatment in patients with melanomas more than 4 mm thick; however, most guidelines recommend margins of 3 cm whenever anatomically possible. Although prophylactic regional lymph node dissections have been used in patients with stage II melanomas, four prospective randomized trials have failed to show a benefit for this procedure in terms of survival.[3,4,5,6]

  Lymphatic mapping and sentinel lymph node biopsy have been used to assess the presence of occult metastasis in the regional lymph nodes of patients with stage II disease, potentially identifying individuals who may be spared the morbidity of regional lymph node dissection and individuals who may benefit from adjuvant therapy.[7,8,9,10,11] The diagnostic accuracy of sentinel lymph node biopsy has been demonstrated in several studies with a false-negative rate of 0% to 2%.[7,12,13,14,15,16] Using a vital blue dye and a radiopharmaceutical agent, which are injected at the site of the primary tumor, the first lymph node in the lymphatic basin that drains the lesion can be identified, removed, and examined microscopically. If metastatic melanoma is detected, a complete regional lymphadenectomy can be performed in a second procedure. To ensure accurate identification of the sentinel lymph node, lymphatic mapping and removal of the sentinel lymph node should be performed prior to wide excision of the primary melanoma.

  To date, no published data from prospective trials are available on the clinical significance of micrometastatic melanoma in regional lymph nodes, but some evidence suggests that for patients with tumors of intermediate thickness and occult metastasis, survival is better among those patients who undergo immediate regional lymphadenectomy than it is among those who delay lymphadenectomy until the clinical appearance of nodal metastasis.[6] Because this finding arose from a posthoc subset analysis of data from a randomized trial, it should be viewed with caution. The International Multicenter Selective Lymphadenectomy Trial (MSLT-1) demonstrated that lymphatic mapping and sentinel lymph node biopsy can be performed safely (10.1% minor complications' rate) and with a low false-negative rate (5.2%).[17] However, this rate was only obtained after a surgical experience of 55 cases (i.e., 30 cases to enter the trial and 25 cases during the trial). Full publication of the survival data from this study is pending.

  A retrospective matched-pair analysis of 534 patients found equivalent 5-year overall survival (OS) rates for lymphatic mapping, sentinel lymph node biopsy, and regional lymphadenectomy in sentinel node-positive patients versus elective lymph node dissection. Lymphatic mapping and biopsy of the sentinel lymph node were more effective in identifying occult nodal metastasis in patients with tumors of intermediate thickness.[18]