based on data from a randomized, multicenter trial of 936 patients.
“Over time, and in light of the findings of several randomized studies, less extensive surgery for primary melanoma with tumor thickness greater than 2 mm has become more established,” and most recent guidelines recommend a 2-cm margin for these tumors, wrote Deborah Utjés, MD, of the Karolinska Institute in Stockholm and colleagues.
To reinforce the safety and effectiveness of the 2-cm margin, the researchers conducted an open-label, randomized trial of clinically staged melanoma patients aged 75 years and younger with localized cutaneous melanomas thicker than 2 mm, from January 1992 to May 2004. Patients were treated in Denmark, Estonia, Norway, and Sweden. The findings were published in the Lancet.
Patients were randomized to treatment with a 2-cm (471) or 4-cm excision margin (465). The melanomas were located on the trunk, upper extremities, or lower extremities.
The primary outcome of overall survival was similar between the groups. Over a median 20-year follow-up period, the death rate was approximately 50% in each group (49% in the 2-cm group and 51% in the 4-cm group). Disease-specific survival rates were similar as well. Of the 621 reported deaths, 397 were attributed to melanoma: 192 (48%) in the 2-cm group and 205 (52%) in the 4-cm group.
The study findings were limited by several factors, including a lower-than-expected number of patients, lack of nodal staging during the study period, and a focus only on the surgical margin without recording data on pathological excision margins.
However, the extended follow-up supports the safe use of the 2-cm margin for the treatment of melanomas thicker than 2 mm, the investigators wrote. In addition, results from an ongoing trial comparing 1-cm and 2-cm margins for melanomas at least 1 mm thick may yield more evidence to support still narrower surgical margins for some cutaneous melanomas.
The study notes that guidelines from organizations that include the American National Comprehensive Cancer Network and the American Academy of Dermatology recommend the 2-cm margin for tumors that are thicker than 2 mm.
The study was supported by the Swedish Cancer Society, Stockholm Cancer Society, Swedish Society for Medical Research, and the Stockholm County Council, and by funds from Radiumhemmet Research and Wallström. The authors reported no disclosures.
SOURCE: Utjés D et al. Lancet. 2019 Jul 4. doi: 10.1016/S0140-6736(19)31132-8.