Surgical Margins in Melanoma

The standards set for wide excision of melanoma:
- Are well-studied and are the result of:
  - Five randomized, prospective trials
Two trials:
- The French Cooperative Group Trial and the Swedish Melanoma Trial Group:
  - Analyzed melanomas 2 mm in depth
  - Comparing 2-cm and 5-cm margins
  - The findings of these studies demonstrated:
    - No increased risk of local or distant recurrence associated with the smaller margin
The World Health Organization (WHO) Melanoma Trial number 10:
- Also analyzed patients with melanomas 2 mm in thickness:
  - But compared 1-cm and 3-cm margins
- It also demonstrated no difference in overall survival:
  - Although among the patients with a melanoma of 1- to 2-mm thickness:
    - The rate of local recurrence was slightly higher when a 1-cm margin was used:
      - The difference was not statistically significant, however:
        
        And the recommendation from this trial was that a 1-cm margin was safe for lesions 2 mm Breslow thickness:
        
        Although the rate of local recurrence in the 1- to 2-mm subgroup may be higher with this margin
The Intergroup Melanoma Trial:
- Analyzed all patients with a melanoma of intermediate thickness (1 to 4 mm)
- The authors compared 2-cm and 4-cm margins and, despite the inclusion of patients with melanomas 2 mm thick:
  - No difference was seen in overall survival or local recurrence
- This trial demonstrated that a 2-cm margin of excision was safe for patients with a melanoma of up to 4 mm thick:
  - But did not address patients who had a lesion greater than 4 mm thick
The British Cooperative Group Trial:
- Analyzed patients with lesions greater than 2 mm in thickness and randomly assigned them to 1-cm margins or 3-cm margins
- This trial demonstrated a greater risk of recurrence among patients who had a 1-cm margin of excision:
  - However, importantly, this trial did not include SLN biopsy, and the greatest incidence of recurrence was regional:
    - When accounting for regional recurrence, the differences between groups were no longer statistically significant
  - Given this limitation, the application of these results to the standards in regions where SLN is routinely applied becomes somewhat ambiguous
  - Finally, the overall survival in both arms was not statistically different
Margins are measured grossly, not microscopically:
- Therefore pathologic analysis after resection does not require repeat resection (except in the setting of positive margins) to ensure the appropriate distance
- There is no role for compromise of these standards, i.e., biopsy margins cannot be added to planned surgical margins to obtain a total excision margin (i.e., 5 mm plus 5 mm):
  - Therefore, wide excision is planned around the biopsy site or the known primary lesion with the appropriate margin at the time of definitive wide excision:
    - In areas of anatomic or functional constraint, such as the hand or the face:
      - Margins may be compromised from the set standards:
      - In settings where margins must be compromised:
        
        Local recurrence does not appear to have an impact on overall survival
Sentinel lymph node biopsy:
- Should be discussed and offered for patients with melanoma greater than or equal to 0.8 mm in thickness
- Melanomas less than 0.8 mm thick with the presence of high-risk features such as:
  - The presence of ulceration
Ultrasound surveillance of the regional lymph node basin(s):
- Would be indicated only in the instance of a primary tumor that failed to localize on preoperative lymphoscintigraphy
Reference
- Balch CM, Houghton AN, Sober AJ, et al, eds. Cutaneous Melanoma. 5th ed. St. Louis, MO: Quality Medical Publishing; 2009.
- National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology. Melanoma. Available at http://www.nccn.org.
- Morton DL, Cochran AJ, Thompson JF, et al. Sentinel node biopsy for early stage melanoma: accuracy and morbidity in MSLT-I, an international multicenter trial. Ann Surg. 2005;242:302-311.