After controversies regarding which are the best surgical excision margins for skin melanomas thicker than 2 mm, a study published Online First by The Lancet indicates that a 2 cm excision margin is safe and sufficient, as results in similar levels of recurrence and death compare with that of 4 cm margin.

Skin melanoma is rising by about 4% in both men and women in Sweden. Figures in Scandinavia and other countries with predominantly white populations are also increasing, and compared with other cancers, the average age of patients diagnosed is low. Doctors have to strike a balance when surgically removing melanomas, as there may be the risk of relapse if the excision is too narrow. This could compromise disease-free survival and in the worst-case scenario even result in death.

Dr Peter Gillgren at the Karolinska Institutet and Stockholm Söder Hospital in Stockholm, Sweden, and his team conducted a randomized controlled trial in nine European centers across Sweden, Norway, Denmark, and Estonia to establish which size of excision would be most appropriate. The trial involved a total of 936 patients at clinical stage IIA-C with skin melanoma that was thicker than 2 mm with the primary endpoint being survival.

Researchers divided participants into 2 groups, with one group of 465 participants allocated to receive a 2 cm-resection and the second group of 471 participants who received a 4-cm resection. Although each group lost one patient to follow-up, their data was included in the analysis.

At the median follow up at approximately 7 years, the researchers discovered that similar numbers of patients in each group had died i.e. 39% (181) patients in the 2-cm group and 38% (177) in the 4-cm group. Both the 5-year overall survival was the same at 65% in both groups as was the 5-year-recurrence at 44%, meaning that 56% of patients in both groups did not have a relapse.

At present, recommendations in terms of the size of surgical excision margins commonly vary between 2 and 3 cm in different countries. The researchers also pointed out that in surgical sections of 2 cm, the skin can be closed without the need of skin grafts or skin flaps in most cases. Wider excisions could also potentially lead to lymphatic obstruction, bad cosmetic results, long hospital stays as well as a frequent need for skin grafts, or complicated skin flap reconstructions.

Based on their findings, the researchers suggest:

"Our large study shows that melanoma patients with a tumor thicker than 2 mm can be safely treated with a 2-cm margin without any effect on overall survival and recurrence...meta-analysis should be done of all randomized trials of cutaneous melanoma thicker than 2 mm."

Professor John F Thompson from the Melanoma Institute Australia in North Sydney, NSW, Australia, and Dr David W Ollila from the Division of Surgical Oncology and Endocrine surgery, University of North Carolina at Chapel Hill School of Medicine in Chapel Hill, NC, USA, write in a linked comment:

"The next question to be addressed is whether a 2-cm margin is preferable to a 1-cm margin or whether a 1-cm margin is sufficient and safe. Morbidity and healthcare costs could be decreased if a 1-cm margin is equivalent or non-inferior to a 2-cm margin. A proposal for such a large scale, multicenter trial is being developed."

Written by Petra Rattue