1 cm vs 2 cm wide surgical excision margins for primary cutaneous melanoma

INTERVENTION: A wide local excision involves removing an extra "safety margin" of skin surrounding the original melanoma site, to ensure that any remaining scattered melanoma tumour cells that may have been left behind after the first initial biopsy/surgery are removed. Patients will be randomised 1:1 using a randomisation system to one of two study arms: Experimental: arm A 1 cm wide local excision margin + sentinel lymph node biopsy +/‐ reconstruction Active comparator: arm B 2 cm wide local excision margin + sentinel lymph node biopsy +/‐ reconstruction Years 1 to 2: During the first 2 years patients should attend follow up at 3, 6, 12, 18 and 24 months (+/‐ 2 weeks) after surgery preferably in clinic, however telehealth consultations are permitted Years 3 to 5: Annual follow up study visits should be performed (+/‐ 4 weeks) preferably in clinic, however telehealth consultations are permitted. Years 6 to 10: Annual follow up study visits should be performed (+/‐ 4 weeks). These visits are optional and are based on local standard practice or clinician decision. The annual follow up visits in years 6‐10 can be performed via the patient’s regular scheduled study visit or via telehealth consultations with the patient or their treating clinician. If the patient cannot be contacted, survival data will be collected. CONDITION: Cutaneous melanoma ; Cancer ; Melanoma and other malignant neoplasms of skin PRIMARY OUTCOME: Disease‐free survival: time from randomisation to any clinically, histologically or radiologically confirmed local recurrence of melanoma including satellite lesions and in transit metastases to regional draining lymph nodes (time frame: 0‐60 months) INCLUSION CRITERIA: 1. Patients must have a stage II primary invasive cutaneous melanoma with Breslow thickness >2 mm without ulceration, or >1 mm (with ulceration only) (pT2b‐pT4b, AJCC 8th edition) as determined by diagnostic biopsy (narrow excision, incision or punch biopsy) and subsequent histopathological analysis 2. Must have a primary melanoma that is cutaneous (including head, neck, trunk, extremity, scalp, palm, or sole) 3. An uninterrupted 2 cm margin must be technically feasible around biopsy scar or primary melanoma 4. Staging sentinel node biopsy must be completed within 3 months (92 days) of the original diagnosis 5. Patients must be 18 years or older at time of consent 6. Patient must be able to give informed consent and comply with the treatment protocol and follow‐up plan 7. Life expectancy of at least 5 years from the time of diagnosis, SECONDARY OUTCOME: ; 1. Local recurrence: time from randomisation to any clinically, histologically or radiologically confirmed local recurrence of melanoma including satellite lesions and in transit metastases to regional draining lymph nodes (time frame: day 0 ‐ trial completion (max. 120 months)); 2. Distant disease‐free survival: time from randomisation to any clinically, histologically or radiologically confirmed distant recurrence of melanoma (time frame: day 0 ‐ trial completion (max. 120 months)); 3. Melanoma‐specific survival: time from randomisation to death due to melanoma (time frame: day 0 ‐ trial completion (max. 120 months)); 4. Overall survival: time from randomisation to death from any cause (time frame: day 0 ‐ trial completion (max. 120 months)); 5. Melanoma‐specific quality of life measured using the Functional Assessment of Cancer Therapy ‐ Melanoma (FACT‐M) questionnaire at baseline, 3, 6, 12 and 24 months; 6. Neuropathic pain assessed using PainDetect questionnaire at baseline, 3, 6, 12 and 24 months; 7. Health‐related quality of life measured using the EQ‐5D‐5L questionnaire at baseline, 3, 6, 12 and 24 months; 8. Surgery‐related adverse events (wound dehiscence, seroma/haematoma, haemorrhage, infection, skin graft failure, necrosis of flap used for reconstruction, deep venous thrombosis, urinary tract infection, pneumonia, cardiac complications, lymphedema), graded in severity according to the Clavien‐Dindo system, recorded from the time of surgery to 90 days following surgery (inclusive); 9. Adverse events (AEs): for the purposes of this trial, only those pre‐existing conditions and AEs related to the patient’s melanoma diagnosis and/or with study treatment (wide local excision surgery, including sentinel lymph node biopsy) will be reported. AEs and any pre‐existing medical conditions will be recorded at the baseline assessment and routinely until 12 months of follow up, or until the participant withdraws or dies (prior to completing 12 months of follow up).; 10. Health economic evaluation: resource utilisation and cost‐utility analysis from hospital notes, Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Scheme (?PBS) data (Australia) and patient‐reported outcomes (including an employment questionnaire), at baseline, 3, 6, 12, and 24 months and at melanoma recurrence;