Optimal surgery margins in stage 2 melanomas

This study investigated the safe margin (the tissue removed around the tumor during surgery) for stage 2 melanomas (tumors with 1-2 mm in thickness). Researchers suggested that the safe margin during melanoma surgery is between 8 and 16 mm. 

The standard treatment for patients with stage 2 melanomas (tumor between 1-2 mm of thickness) is surgery. During surgery the tumor is removed along with some healthy tissue around it, to make sure that all the cancer is removed. However, when a pathologist examines the removed tissue (under a microscope), the outer edges of this tissue may still have cancer present (this is called positive pathological margins). Because the cancer cells may be beyond the margins of the tumor that can be seen, pathological margins are likely to be a good predictor of the risk of recurrence (when the cancer comes back).

The current guidelines for treating stage 2 melanoma recommend surgical margins between 8 and 16 mm. However, these guidelines did not consider pathological margins.

The objective of this study was to determine the safe surgery margin for patients with tumors between 1-2 mm of thickness. This study also investigated whether the pathological margins were associated with prognosis and survival in these patients.

This study included information on 2131 patients with stage 2 melanoma, with a tumor thickness between 1-2 mm. Patients underwent surgery and were divided into four different groups based on surgical margin. 326 patients had margins of less than 8 mm. 1219 patients had margins between 8 and 16 mm. 544 had margins between 16 and 24 mm. 42 patients had margins of more than 24 mm. The average follow-up period was 46 months.

Of 2131 patients, 1005 were followed for 5 years. Recurrence was observed in 265 (26.4%) of these patients. In 11.1% of these patients recurrence was localized at the original tumor site. 15.6% of patients had a recurrence in a nearby lymph node and 16.1% had a distant recurrence. Patients with margins of less than 8 mm had a significantly higher recurrence rate (38.5%) when compared with patients with margins of 8 mm or more (24.8%).

5-year disease-free survival (DFS; time from surgery to disease progression) in patients with less than 8 mm margins was 75.3%. DFS was 82.6% in the 8-16 mm group. Patients with margins of less than 8 mm were 43% more at risk of developing a recurrence when compared with to the 8-16 mm group.

Increasing surgical margin to 16 or 24 mm did not benefit DFS or recurrence compared to 8 mm or greater. However an increasing deep margin was strongly associated with improved local recurrence. Patients with margins of less than 8 mm were more at risk of local recurrence when compared to the 8-16 mm group.

This study determined that an 8 mm pathological margin is sufficient for stage 2 melanomas.