Melanoma In Situ: New Study Reveals Low Recurrence and Potential for Simpler Treatments

Did you know that a groundbreaking study published in 2025 found no metastases or melanoma-specific deaths in over 400 patients with melanoma in situ, even after years of follow-up? This challenges traditional approaches and highlights the potential for less invasive treatments.

Key Areas We Will Cover

• What melanoma in situ is and why it’s increasing
• Overview of the recent Greek cohort study
• Key findings on recurrence, survival, and excision margins
• Implications for UK patients and NHS guidelines
• Limitations and the need for further research
• Practical advice for skin cancer prevention and monitoring

Introduction

Melanoma in situ (MIS), the earliest stage of melanoma confined to the epidermis, is on the rise in the UK and worldwide. With diagnoses increasing due to better awareness and screening, understanding its prognosis and optimal treatment is crucial. A new retrospective cohort study from Greece, published in JAMA Dermatology in September 2025, provides fresh insights into low recurrence rates for non-lentigo maligna/non-acral lentiginous MIS subtypes. At the SkinCare Network in London, we stay at the forefront of such research to offer evidence-based care. This article breaks down the study’s findings and what they mean for UK patients seeking effective, minimally invasive options.

Understanding Melanoma In Situ

Definition and Subtypes

Melanoma in situ represents stage 0 melanoma, where abnormal melanocytes are limited to the skin’s top layer. It excludes more aggressive subtypes like lentigo maligna (LM) and acral lentiginous melanoma (ALM) in situ, which often require different management.

• Prevalence: In the UK, MIS cases are rising, contributing to overdiagnosis concerns as per Cancer Research UK data.
• Risk Factors: Sun exposure, fair skin, and family history increase susceptibility.

Why Diagnoses Are Increasing

Improved dermoscopy and public awareness campaigns have led to earlier detections. However, this has sparked debates on overdiagnosis, where indolent lesions are treated aggressively without impacting mortality.

• Fact: Studies show MIS patients often have better survival than the general population, suggesting many cases may not progress.

Overview of the 2025 Cohort Study

Study Design and Participants

Conducted at Andreas Sygros University Hospital in Athens from 1991 to 2023, this retrospective study included 401 patients (403 lesions) with non-LM/non-ALM MIS. Median age was 52 years, with a median follow-up of 5.2 years (up to 25.8 years).

• Exclusion Criteria: Patients with prior invasive melanoma or LM/ALM subtypes were omitted.
• Treatment: All underwent initial excisional biopsy; 92.3% had subsequent wide excision.

Methods and Outcomes Measured

Researchers reviewed medical records for demographics, histopathological margins, and outcomes like local recurrence, metastasis, and survival. Statistical analysis used tools like the Mann-Whitney test.

Key Findings from the Study

Low Recurrence Rates

Only one local recurrence occurred in a patient with involved margins who skipped wide excision, developing invasive melanoma after 14 months.

• No Recurrence Groups: 30 lesions with clear biopsy margins and no wide excision showed no recurrences over 8.1 years median follow-up.
• Narrower Margins: 23 lesions with <0.5 cm wide excision margins (mean 0.36 cm) had no recurrences over 4.3 years.

Survival and Metastasis

No patients experienced metastasis or melanoma-specific death. Six suspicious lesions near scars proved benign (nevus or solar lentigo).

• Statistic: 99.5% of patients were alive at last follow-up, with two unrelated deaths.

Implications for UK Patients

Potential Shift in Treatment Guidelines

Current NHS and European guidelines recommend wide excision with 0.5 cm margins for MIS. This study suggests clear margins from initial biopsy may suffice for non-LM/non-ALM subtypes, reducing unnecessary surgeries.

• Benefits: Less scarring, lower costs, and reduced patient anxiety, aligning with UK efforts to combat overdiagnosis.
• UK Context: With rising MIS diagnoses, this could ease NHS burdens; however, consult specialists for personalised advice.

Role of Early Detection

Regular skin checks remain vital. At the SkinCare Network in London, we use advanced dermoscopy to differentiate MIS from benign lesions accurately.

• Tip: Annual screenings for high-risk individuals can catch MIS early, potentially avoiding extensive treatments.