Stage III Melanoma
Melanoma is a skin cancer that affects the skin cells that produce melanin. Stage III melanoma is when the cancer cells have spread to the lymph nodes; stage IIIA has microscopic node involvement; stage IIIB has 1-3 nodes involved; and stage IIIC has more than 4 nodes. The five-year survival according to the American Cancer Society is 78% for stage IIIA, 59% for Stage IIIB, and 40% for Stage IIIC.
The 10-year survival rate is 68% for stage IIIA, 43% for stage IIIB, and 24% for Stage IIIC. The highest risk for recurrence of melanoma is during the first three years after diagnosis. The highest risk is for > 4 nodes involved or size of nodes > 3cm.
In 2019 pembrolizumab (Keytruda) was FDA approved for stage III melanoma following complete resection. The dose of pembrolizumab is 200mg every three weeks intravenously over 30 minutes for a total of 12 months. The benefit of pembrolizumab was irrespective of PD-L1 expression. Pembrolizumab is an anti PD-1 monoclonal antibody that binds to the PD-1 receptor resulting in decreased tumor growth.
For grade one or two infusion reaction the pembrolizumab infusion should be slowed or interrupted. For grade three or four infusion reaction the monoclonal antibody needs to be discontinued. The most common adverse events occurring in at lease 20% of patients are fatigue, pain, anorexia, rash, itching, nausea, diarrhea, fever, cough and constipation.
Other complications that occur less frequently but can be severe and require discontinuation of pembrolizumab are immune mediated pneumonitis, colitis, nephritis, hepatitis, endocrinopathy and skin reactions.
The recurrence-free survival was 20 months in the placebo group and was not yet reached in the pembrolizumab arm. Pembrolizumab is currently standard of care for stage III melanoma.