What is the cure rate for melanoma in situ (malignant melanoma in its initial stage)?

From the Guidelines

Melanoma in situ has an excellent cure rate of approximately 99-100% when treated appropriately with complete surgical excision, as evidenced by the most recent guidelines from 2019 1. The standard treatment involves wide local excision with a 0.5 cm margin of normal skin surrounding the tumor, as recommended by the European Society for Medical Oncology (ESMO) guidelines 1. This high cure rate is due to the fact that melanoma in situ is confined to the epidermis (the outermost layer of skin) and has not yet invaded the deeper dermis, meaning it has not developed the ability to metastasize to other parts of the body. After surgical removal, patients should undergo regular skin examinations, typically every 3-6 months for the first few years, then annually thereafter, to monitor for recurrence or new melanomas, although some guidelines suggest that patients with a surgically treated single in situ melanoma do not require follow up 1. Some key points to consider in the management of melanoma in situ include:

• Wide local excision with a 0.5 cm margin is recommended for in situ melanomas 1
• Sun protection is essential following treatment, including daily use of broad-spectrum sunscreen with SPF 30+, wearing protective clothing, and avoiding peak sun hours
• The excellent prognosis for melanoma in situ underscores the importance of early detection and treatment of skin cancers before they progress to invasive stages. It's worth noting that the management of lentigo maligna and in situ melanoma may present unique problems due to the characteristic, yet unpredictable, subclinical extension of atypical junctional melanocytic hyperplasia, which may extend several centimeters beyond the visible margins, as discussed in the National Comprehensive Cancer Network (NCCN) guidelines 1.

From the Research

Cure Rate for Melanoma in Situ

The cure rate for melanoma in situ (MIS) can be determined based on the treatment method and patient follow-up.

• The study by 2 reported a cure rate of 93.3% after using topical imiquimod for residual head and neck melanoma in situ.
• Another study by 3 found a cure rate of 98.6% for MIS treated with Mohs micrographic surgery, with a mean follow-up of 50 months.
• The same study by 3 also reported a cure rate of 98.2% for MIS treated with Mohs micrographic surgery, with a mean follow-up of 63 months.
• A study by 4 reported a recurrence rate of 1.1% after complete excision of MIS, and a recurrence rate of 2.9% for the Lentigo Maligna (LM) subgroup.

Treatment Methods and Recurrence Rates

Different treatment methods have varying recurrence rates for MIS.

• Mohs micrographic surgery has been shown to have low local recurrence rates, with one study by 5 reporting a recurrence rate of 0.1%.
• Surgical excision with at least 5-mm margins is the standard therapy, but a study by 6 found that bread-loafing may not be reliable for detecting residual melanoma at the surgical margins.
• Topical imiquimod has been proposed as a treatment for residual MIS, with a study by 2 reporting a cure rate of 93.3% after treatment.

Factors Affecting Cure Rate

Several factors can affect the cure rate for MIS, including:

• The type of MIS, with the LM subgroup having a higher recurrence rate after complete excision 4.
• The treatment method, with Mohs micrographic surgery and topical imiquimod reporting high cure rates 2, 3.
• The follow-up time, with longer follow-up times reporting slightly lower cure rates 3.