Treatment options for advanced non-melanoma skin cancers are ever-changing. Dr. Diwakar Davar reviews current treatment options and discusses which medical professionals are involved in treating advanced non-melanoma skin cancers.
Dr. Diwakar Davar is the Clinical Director of the Melanoma and Skin Cancer Program at UPMC Hillman Cancer Center. Learn more about Dr. Davar.
What approaches are currently available to treat these more common forms of advanced non-melanoma skin cancer?
Right now, the most common mode of treatment is typically treating cancer that is localized.
Again, even with the extremely increasing incidence of these cancers, the vast majority of cancers that we detect are still localized and are amenable to easy surgical eradication by a trained dermatologist or a trained mole surgeon. A trained dermatologist, a trained mole surgeon, a plastic surgeon, these are commonly the physicians that encounter these patients. Surgical removal is still the primary mode of eradications of these lesions. However, increasingly, there is a role for early systemic therapy and local regional therapy to improve patient outcomes for reasons that we can talk about. Still, the vast majority of patients are still treated surgically and then increasingly, there is the role for referral to medical oncologists and radiation oncologists to talk about alternative forms of treatment that may be needed after that.
What sort of alternative therapies? Are you looking at targeted therapies? Immunotherapies?
The primary reason for which advances have happened in this disease is really the advent of effective systemic immunotherapy and the spillover of immunotherapy into the patient landscape in these diseases. The reason for that is as follows. Immunotherapy essentially is most effective in tumors that carry a high tumor mutation burden. For example, melanoma has a tumor mutation burden on average of about 15, and the tumor mutation burden in melanoma is driven by the fact that melanoma, cutaneous melanoma is an ultraviolet light-driven skin cancer.
However, non-melanoma skin cancers have tumor mutation burdens that are many, many magnitudes higher than that of melanoma. For example, the median tumor mutation burden in cutaneous squamous cell carcinoma is 50. Melanoma is 15. The median tumor mutation burden in cutaneous squamous cell carcinoma is three times that of melanoma. Similarly, for Merkel cell carcinoma. A large majority of Merkel cell carcinoma is caused by an unusual virus known as a Merkel cell polyomavirus. Both the viral driven tumors and the non-viral driven tumors have high tumor mutation burdens, and the same is true of basal cell carcinoma because of ultraviolet light exposure.
The primary reason why immunotherapy has gotten a foothold in these diseases is because the underlying etiologic agent that drives carcinogenesis, ultraviolet light for the majority of these, and the Merkel cell polyomavirus for the subcategory of non-melanoma skin cancer that is Merkel are both associated with a response to immunotherapy.
As a result of that, immunotherapy, anti-PD-1 immunotherapy is now standard of care for patients with tumors that are either locally advanced undissectible or locally advanced and/or metastatic, that is, that they have spread. They are now available for use and FDA-approved for this indication in both Merkel, basal, as well as non-melanoma cutaneous squamous cell carcinoma.