Non-invasive Testing to Diagnose Skin Cancer
Posted on: January 24, 2018
Mr. R is a 58 year old man with a history of recurrent basal cell carcinoma; in 2013 a dermatologist treated skin cancer on the right side of his nose by shaving off layers of skin in what is called Mohs surgery. Three years later, in 2016, Mr. R developed a basal cell carcinoma on the left side of his nose and got treated with radiation therapy. Recently, he noticed a new rough red spot on the left side of his nose. While concerned that it might be cancer, his immediate reaction was something many people can identify with: “Is there any other way to diagnose skin cancer without cutting off a piece of my skin?”
Basal cell carcinoma (BCC) of the skin is one of the most common malignancies diagnosed in the US, with over 4 million new cases each year. The lesions occur most frequently on sun-exposed skin in Caucasians, and people who have a history of BCC are at a higher risk of developing future lesions. BCC is associated with exposure to ultraviolet light from the sun, tanning beds, therapeutic radiation, or immunosuppression. BCC also occurs more often in men over 40 years old.
Basal cell carcinoma may be diagnosed by a doctor during a clinical examination, but a skin biopsy is usually done to confirm the diagnosis. Shave biopsies or punch biopsies are often performed, or lesions may be surgically removed for diagnosis. Unfortunately, the best way to diagnose skin cancer is by undergoing a biopsy.
Fortunately, researchers are developing less invasive methods for diagnosing skin cancers, such as Dermtech’s Pigmented Lesion Assay, or PLA. This PLA test uses a sticky adhesive patch (similar to Scotch tape) to gather skin cells from a lesion. The sample is then analyzed for specific RNA molecules to diagnose melanoma, with a reported false positive rate of <1%. This test is available for the detection of melanoma, but the company is also developing a similar test for other skin cancers as well. Initial studies of this method showed promising results in identifying primary basal cell carcinomas and squamous cell carcinomas. For a patient, this would mean that instead of undergoing a procedure with a scalpel, the diagnosis could be made without any incisions at all.
To answer my patient’s question: unfortunately, for now, the answer is no – biopsies remain the best method for diagnosing skin cancers. In the future, however, newer genetic tests may allow doctors to diagnose skin cancer non-invasively, without the need for scalpels or stitches.
Dr. Chung is a board certified radiation oncologist with Diablo Valley Oncology & Hematology Medical Group in Pleasant Hill. She has a special interest in treating skin and breast cancer. Dr. Chung sees patients in Pleasant Hill and Berkeley. For more information call: 925-677-5041.