WoW - Single- vs Two-staged Excisions of Thin Melanoma

Melanoma is one of the most common forms of skin cancer and has become the third most common type of cancer among men and the fourth most common among women in Sweden. The mortality associated with melanoma is strongly linked to the thickness of the original tumor. Thicker tumors generally have a worse prognosis compared to thinner tumors. In melanoma in situ (MIS), the tumor is confined to the epidermis and cannot spread. In invasive melanoma, the tumor has grown into the dermis. The thickness of these invasive melanomas is measured using the "Breslow thickness." Thinner invasive melanomas with a Breslow thickness of ≤1.0 mm constitute the majority of cases in Sweden and have an excellent prognosis with a 10-year disease-specific survival rate of 97%. Melanoma represents a significant economic burden with increasing healthcare costs. Early detection and cost-effective treatment strategies are therefore important to improve prognosis, reduce costs, and avoid unnecessary overtreatment. Surgical methods for treating melanoma vary depending on the thickness of the tumor. Traditionally, a two-step procedure has been used. Initially, a diagnostic excision (surgery to remove the tumor) with a narrow clinical margin is performed. Once melanoma is confirmed, a second wide local excision (WLE) is performed around the surgical scar with a 1-2 cm clinical margin depending on the exact Breslow thickness. This method has evolved over time, and narrower clinical margins are now used in the WLE than previously. However, researchers have begun to question whether a WLE is necessary at all for thin melanomas if the tumor is completely removed during the initial diagnostic excision. Researchers are now exploring a more personalized treatment strategy that considers histopathological margins instead of a standardized clinical margin. For well-defined melanomas, a clinical margin of 3-5 mm may be sufficient to ensure that the melanoma is removed with an acceptable histopathological margin (≥1.5 mm). The hypothesis is that this margin may be adequate and that the WLE does not reduce the risk of local, regional or distant disease nor melanoma-specific death. If the hypothesis is proven, unnecessary surgery, patient suffering, risk of complications, resource utilization, and healthcare costs could be reduced. The investigators now want to investigate whether there is a difference in the risk of recurrence, spread, and/or death for patients with thin melanomas (≤1mm Breslow thickness) treated with only one excision compared to the current standard of two excisions.