general-surgery

Melanoma

Melanoma is a skin cancer that is often but not always related to sun exposure. Melanoma typically occurs in sun-exposed skin but can rarely occur in other areas e.g. eyes, sole of foot and perianal region. Melanoma arises at the top layer of skin ( often called “superficial spreading”) and over time, invades the deeper layers (“vertical growth phase”). The thickness of the melanoma within the skin layers has correlation with the chances of recurrence. In other words, the thicker the melanoma, the higher the risk of recurrence and potential for spread. The best possible outcome is achieved when melanoma is removed early or even at a precancerous stage. The term “Breslow’s thickness” is used to describe this thickness which is measured in millimetres under microscopic examination.

Treatment requires wide excision of the melanoma with appropriate margins. An initial excision biopsy is usually performed on a suspicious mole and if melanoma is confirmed, the Breslow’s thickness is determined and definitive excision planned. The margin of clearance (distance of the melanoma from the excision margin) is guided by the Breslow’s thickness and the required margin of clearance is usually between 1 to 2 cm.

For melanoma with a Breslow’s thickness of more than 1 mm, there should be a consideration for performing a Sentinel Lymph Node Biopsy at the same time as the definitive procedure. The Sentinel node is the first lymph node which receives drainage from lymphatics within a specific region. By removing the sentinel node, one can determine whether melanoma cells have spread to the node itself. This will help with predicting long term outcome and will guide the need for further surgery. The technique involves injecting a small volume of radioisotope solution prior to surgery and performing a lymphoscintiscan to determine the position of the sentinel nodes. A gamma probe is used during surgery to localize and remove the radioactive sentinel nodes. It is important that the sentinel node biopsy procedure is performed by a surgeon who is specifically trained in the technique and regularly performs the procedure. This will ensure that the correct lymph node is removed so that an accurate result can be obtained.

If a sentinel node, or for that matter, any lymph node is involved with melanoma, further investigation and treatment will be necessary. This includes staging investigation with CT and/or PET scan. In cases of nodal metastasis, definitive surgery necessitates the removal of lymph node groups within a specific region. This is known as Nodal Clearance or Nodal Dissection. The terminology for this procedure will vary depending on the site of the nodal involvement e.g. Axillary Dissection (for nodes in the axilla/armpit), Neck Dissection and Groin Dissection. Once completed, referral to an Oncologist may be required for consideration of other treatment modalities e.g. Radiotherapy, drug therapy. There has been significant progress in recent times with regards to drug treatment (e.g. BRAF Inhibitor) for melanoma with promising results achieved in cases of metastatic disease. This will likely become a standard treatment option for patients with melanoma in the near future.

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