What is the latest in immunotherapy for melanoma? I had PUVA therapy.

The PUVA therapy occurred in the 70’s and 80’s. As a result have have constantly reoccurring squamous cell cancers treated with 5fu every month. 2 years ago I had a melanoma insitu removed from my back. Yesterday I had one removed from my right arm. I have many dark spots on my arms. Is there any way to remove the dark spots so they do not evolve into melanoma?