SAN DIEGO—The cancer field is rich with registry data on lung cancer, breast cancer, and other types of cancer, but there is no such data available for squamous cell and basal cell carcinoma of the head and neck. This leaves a limited evidence base for learning how to identify a high-risk case and how to choose treatments accordingly, an expert said here during a panel discussion at the Triological Society Combined Sections Meeting.
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March 2020But enough data from the literature is available to give some guidance, said Timothy Johnson, MD, professor of dermatology and otolaryngology-head and neck cancer at the University of Michigan in Ann Arbor. He encouraged clinicians and surgeons to run through a checklist of factors when they see these lesions.
Risk Determines Approach
In basal cell carcinoma, the most high-risk areas for subclinical extension and local recurrence are anywhere on the face other than the middle-risk areas of the cheek, forehead, scalp, and neck, according to National Comprehensive Cancer Network guidelines. Lesions in those middle-risk areas become high risk if they are 10 mm or bigger, and low risk if they’re smaller than that, Dr. Johnson said. Other risk factors are recurrent lesions, lesions with the aggressive growth or micronodular histologic patterns, neurotropism, a site of prior radiation, immunosuppression, and poorly defined borders.
“When I look at a basal cell, I ask myself (about) these eight factors,” he said. “The majority of basal cell skin cancers are small, low-risk lesions.” Most can be treated with excision, radiation or curettage, and electrodessication, he said, with cure rates on par with Mohs surgery.
“But when you start seeing more of these factors, you need to start considering Mohs surgery,” Dr. Johnson said. “Or, if you’re going (to do) standard incision, consider wider margins and deeper margins.”
Squamous cell carcinoma involves the same locations, tumor sizes, and other considerations as basal cell when it comes to assessing risk. Clinicians also should consider tumors to be high risk when they are 2 mm or greater in thickness, or they penetrate through the bottom layer of the dermis into fat. Tumors arising from radiation, those with rapid growth, and chronic inflammation such as an ulcer or a burn scar are also high-risk lesions, he said.
The majority of basal cell skin cancers are small, low-risk lesions. —Timothy Johnson, MD
Dr. Johnson said when many of these risk factors are present, he considers a sentinel lymph node biopsy for staging.