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TIP2. Melanoma Margins Trial-II: 1cm v 2cm Wide Surgical Excision Margins for AJCC Stage II Primary Cutaneous Melanoma (MelMarT-II)

Friday, March 6, 2026
3:51 PM - 3:55 PM MST
Location: Immuno-Oncology HUB Zone
Background: Wide local excision is standard treatment after diagnostic biopsy of primary cutaneous melanoma, yet the optimal margin for high-risk stage II disease remains debated. Although previous randomised trials support narrower margins in lower-risk melanoma, data for thicker tumours remain conflicting and concerns persist that wider excision may not improve oncological control yet increases morbidity and contribute to poorer patient experience and the likelihood of added reconstructive surgery. The MelMarT-1 pilot trial demonstrated the safety and feasibility of a randomised trial of excision margins resulting in the definitive phase III trial to clarify margin adequacy in stage II melanoma and address the potential excess morbidity associated with wider excision.


Methods: MelMarT-II is an international, multicentre, phase III randomised controlled non-inferiority trial comparing 1 cm versus 2 cm excision margins for local treatment of primary melanoma. Adults aged 18 years or older with cutaneous melanoma staged pT2b to pT4b (AJCC 8th edition) are eligible following diagnostic excision biopsy. All anatomical sites are eligible and patients are staged with sentinel node biopsy as standard of care. Participants are randomised 1:1 to a 1 cm or 2 cm radial excision margin around the primary scar. Randomisation is stratified by age, AJCC stage (IIA, IIB, IIC) and country. The primary endpoint is disease-free survival. Key secondary endpoints include melanoma specific survival, distant metastasis-free survival, surgical morbidity and reconstruction burden, and patient-centred outcomes incorporating quality-of-life assessment and health economic analysis. The sample size of 2,998 participants provides 80 percent power to demonstrate non-inferiority of the 1 cm margin. The primary analysis will follow the intention-to-treat principle. Recruitment has been completed across 9 countries in North America, Europe and Australasia and follow-up (5 years post randomisation) is ongoing. A planned a priori interim analysis is underway. The trial is coordinated by MASC Trials in Melbourne, Australia with international collaboration.
Clinical trial registration: NCT03860883

Learning Objectives:

  • Describe rationale for wide local excision for primary cutaneous melanoma.
  • Describe the inclusion criteria for MelMarT-Ii
  • Describe the study design of MelMarT-II and the stratification levels.