The goal of this clinical trial is to compare the safety and effects of sulforaphane with the safety and effects of placebo on people's risk of developing melanoma. The main question it aims to answer is:

Will giving sulforaphane (a broccoli sprout extract) have a meaningful effect on how your atypical moles change over time? If there is an effect, will this lower your risk of developing melanoma?

Participants will:

Take sulforaphane or a placebo for 12 months Visit the clinic once every 3 months for checkups and tests You will keep a calendar which will help you keep track of when you take your tablets

Inclusion Criteria:

• Patient must have ≥ 3 clinically atypical nevi, assessed within 30 days prior to randomization, that are consistent with the International Agency for Research on Cancer (IARC) definition as follows.27
• Must have a diameter of ≥ 5mm in one dimension
• Must include a macular component in at least one area
• Must have at least two of the following features: ill-defined borders, color variegation, uneven contour, and erythema
• Patient must have a prior diagnosis of early-stage melanoma, defined as either melanoma in situ, localized resected stage I-II node negative melanoma, or resected node positive stage III melanoma who in the assessment of their physician have a low risk of relapse of their prior melanoma within one year of randomization.
• Patient must not be currently on targeted or checkpoint immunotherapy or treated within 365 days prior to randomization.
• Patient must be ≥ 18 years of age.
• Patient must have the ability to understand and the willingness to sign a written informed consent document. Patients with impaired decision-making capacity (IDMC) who have a legally authorized representative (LAR) or caregiver and/or family member available will also be considered eligible.
• Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months of randomization are eligible for this trial.
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated.
• Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load.
• Patients with a prior or concurrent malignancy (other than the melanoma for which they are on this study), whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen, are eligible for this trial.

Exclusion Criteria:

• Patient must not be pregnant.
• Patient must not have a known allergy to cruciferous vegetables.
• Patients must not use any other sulforaphane-containing dietary supplement during the study period.
• Patient must not be on any current systemic treatment for melanoma.