“Melanoma is treated by boosting the immune system.”
Early in the 20th century one of the cures for skin cancer was exposure to sunlight. There were some clinics in Europe in the mountains where people would soak up the sun as therapy (there were reportedly cures, but I don’t know much about it).
Sunlight gets converted to Vitamin D in the body, which has been shown to prevent cancer.
D is critical with cancer, both prevention and aid in combating it. it is interesting that the recurrence of Malignant melanoma is less for those who get sun compared to those who shun it. It is all in vitamin D.