What is the recommended excision margin for a pT2a melanoma?

From the Guidelines

For a pT2a melanoma, the recommended excision margin is 1 cm, as stated in the most recent guidelines 1. This means that during the surgical removal of the melanoma, the surgeon should remove 1 cm of normal-appearing skin around the visible or previously biopsied melanoma site. The purpose of this margin is to remove any potential microscopic spread of melanoma cells beyond the visible tumor, reducing the risk of local recurrence. The excision should extend down to the fascia (the layer covering the muscles) to ensure adequate depth. After excision, the specimen should be sent for pathological examination to confirm clear margins. If the pathology report shows that cancer cells extend to the edge of the specimen, additional surgery may be needed to achieve clear margins. This recommendation balances the need to remove all cancer cells while preserving as much normal tissue as possible, and is supported by the guidelines from the Journal of the American Academy of Dermatology 1. Some studies have suggested that wider margins may be associated with a slightly lower rate of local recurrence, but this has not been shown to improve overall survival 1. The European Organisation for Research and Treatment of Cancer (EORTC) has also recommended excision margins of 1 cm for tumors with a thickness of up to 2 mm, and 2 cm for thicker tumors 1. Overall, the recommended excision margin for a pT2a melanoma is 1 cm, based on the most recent and highest quality evidence.

Key points to consider:

• The excision margin should be based on the tumor thickness, with 1 cm recommended for pT2a melanomas 1.
• The excision should extend down to the fascia to ensure adequate depth.
• Pathological examination of the specimen is necessary to confirm clear margins.
• Additional surgery may be needed if cancer cells are found at the edge of the specimen.
• The recommendation balances the need to remove all cancer cells while preserving normal tissue.

From the Research

Excision Margin for pT2a Melanoma

• The optimal excision margin for primary cutaneous melanoma, including pT2a, is a topic of ongoing debate 2, 3, 4.
• A systematic review and meta-analysis found no statistically significant difference in locoregional recurrence, distant recurrence, or death between narrow (1-2 cm) and wide (3-5 cm) excision margins 2.
• A retrospective study based on the Surveillance Epidemiology and End Result (SEER) database found that wider excision margins (>2 cm) did not provide additional therapeutic benefits compared to narrow excision margins (1-2 cm) for high-risk primary melanoma of the skin thicker than 2 mm 3.
• Another study found that a 2-cm margin is adequate and safe for high-risk primary melanoma of the skin thicker than 2 mm 3.

Surgical Considerations

• Wide local excision prior to sentinel lymph node biopsy may disrupt lymphatic channels, but studies have shown that sentinel lymph node biopsy can still be successfully performed after previous wide local excision 5, 6.
• A pilot international study (MelMarT) compared 1-cm and 2-cm surgical margins for patients with primary melanoma >1 mm in Breslow thickness and found that more patients in the 2-cm margin group required reconstruction, but there was no difference in quality of life between groups 4.

Key Findings

• Narrow excision margins (1-2 cm) may be sufficient for pT2a melanoma, with no significant difference in outcomes compared to wide excision margins (3-5 cm) 2, 3.
• The choice of excision margin should be individualized based on tumor characteristics, patient factors, and surgical considerations 2, 3, 4.