The main aim of wide excision of melanoma after a diagnostic excision is to prevent the cancer recurring at the site of origin, and to maximize long-term survival. The functional and cosmetic impact of surgery on an individual patient, are major secondary considerations when planning a further excision.
Our current theory of how further surgery helps control melanoma is that a wider excision will likely remove any residual tumour cells at the site of origin of the tumour and any microsatellites of disease that may exist in the skin near the tumour, or in the local lymphatic system.
Although there is consensus that after a diagnostic (usually 2mm wide margin) excision, a further excision is beneficial in reducing the risk of local recurrence, the optimal width of a further excision has long been debated. The Scottish Physician, William Handley studied the lymphatic drainage of breast cancer and melanoma, and in the early 1900s suggested performing an approximately 5cm wide excision of melanoma with removal of the draining lymph nodes.
The contemporary approach to wide excision is based on good quality randomised trials of different margin widths, which tested the benefit of different margins of excision of the primary melanoma guided by the Breslow thickness of the primary tumour (i.e. testing with many patients randomly assigned to different excision margins to see if the recurrence rate of a melanoma is the same for a given Breslow thickness melanoma).
For example, the MSG/BAPS randomized trial, recently presented and subsequently published in the Lancet Oncology by my colleague Mr Andrew Hayes of the Royal Marsden, on behalf of his trial colleagues asked the question of whether a 1cm or 3cm excision margin is best for a 2mm Breslow (Stage II) melanoma. Long-term follow up of the 900 patients with Stage II melanoma recruited throughout the UK and randomly assigned either a 1cm or 3cm excision demonstrated no difference in overall survival with a wider excision of 3cm.
The current NICE guidelines recommend a margin of at least 1cm to people with a diagnosis of stage I melanoma (Breslow depth 1-2mm), and margin of at least 2cm to people with stage II melanoma (Breslow depth 1-2mm). For melanoma in situ, a 0.5cm margin is sufficient. Occasionally, in a cosmetically sensitive area, close clinical surveillance after a narrow excision may be considered.
The procedure may be performed by a Dermatologist, General Surgeon, GP or Plastic Surgeon, often as a day case under local anaesthetic. Usually, the wound can be closed primarily with sutures (beneath the skin sometimes) or skin clips; however, if the area is difficult to close, a skin graft or other Plastic surgical procedure may be required to close the excision site. If reconstruction, a 2cm excision, or a sentinel node biopsy is being performed at the same time, a general anaesthetic is generally required. It is important to realise that the excisions may be quite long, as one needs to make the length of the incision longer than the width to close the wound neatly and ensure it is apposed.
Usually, the wound is covered for 24-48 hours, and sutures or clips removed between 5-14 days later depending on the location of the wound, and you will be scheduled a follow-up appointment to ensure good wound healing, removal of sutures and discussion of the pathology examination of the specimen.