Conference Coverage

Fine-tune staging for better SCC risk stratification


 

EXPERT ANALYSIS FROM ODAC 2019

– When caring for individuals with sun-damaged skin, dermatologists need comfort with the full spectrum of photo-related skin disease. From assessment and treatment of actinic keratoses (AKs) and field cancerization, to long-term follow-up of cutaneous squamous cell carcinomas (SCCs), appropriate treatment and staging can improve patient quality of life and reduce health care costs, Vishal Patel, MD, said at the Orlando Dermatology Aesthetic and Clinical Conference.

Dr. Vishal Patel, director of cutaneous oncology at GW Cancer Center, Washington. Kari Oakes/MDedge News

Dr. Vishal Patel

“Actinic keratosis/squamous cell carcinoma in situ is not a disease; it’s a symptom of cutaneous carcinogenesis or field cancerization,” said Dr. Patel, director of cutaneous oncology at George Washington University Cancer Center, Washington. On the other hand, he added, “field disease can be a marker for invasive squamous cell carcinoma risk, and it requires field treatment.” Treatment that reduces field disease is primary prevention because it decreases the formation of invasive SCC, he noted.

“But this level of disease – AKs and SCC in situ – doesn’t kill people,” he emphasized. “I want to leave you with an ability to stage this disease,” said Dr. Patel, noting that SCC mortality may eventually surpass melanoma mortality as deaths from the latter decline and numbers of older Americans with high ultraviolet light exposure and other risk factors climb.

While the majority of AKs regress within 5 years, he looks at the total burden of AKs as a marker for field cancerization “because having less than five in situ or actinic lesions puts you at less than a 1% risk of squamous cell carcinoma formation. Having more than 20 increases that risk 20-fold to 20%,” he said. “That’s the way we need to start thinking about this: Is this a disease – or a symptom?”

Rather than thinking of each AK or SCC in situ as a separate disease event, “the disease we need to be focusing on and treating is field cancerization,” he continued. Within this context, “we should not be thinking that … we need to be aggressive in our management,” which is what results in high costs.

“The reality is that this is a big quality of life issue for our patients. So what do we do?” Field treatment is appropriate for field disease, he said. Dr. Patel said that at GW only field treatment is used; destructive treatment for AKs and SCC in situ is not used. In the absence of patient and lesion characteristics that elevate risk,“surgery is really not the standard of care for in situ lesions for us,” he commented.

“We start by discerning the field disease from the invasive disease” with an initial round of field treatment and, if needed, adjunctive oral chemoprophylaxis. “We lather, rinse, and repeat” the field therapy, continuously if needed, Dr. Patel said.

“We like to do that because we can then identify those specific lesions we want to go after. No cryosurgery, no destructive therapy, because we run the risk of burying those tumors under the scar. They may recur and make it more difficult to accurately stage them in the future,” he noted.

“I like to be more sophisticated in thinking about our approach to the outcomes of these individual lesions,” he said. When it comes to excising lesions that have been biopsied and show invasive SCC, “disc excision may be a more cost-effective way to treat many low-risk SCCs,” he noted. In any case, “removal with clear surgical margins is key.”

Primary tumors with such low-risk attributes as diameter under a centimeter and thickness under 2 mm; well-defined borders; location on the trunk, neck, or extremities; well-differentiated histology; and lack of perineural invasion can all be considered for a disc technique, especially if the patient is immunocompetent without background chronic inflammation or a history of prior radiation therapy.

Staging SCCs, said Dr. Patel, is where things really get tricky. Older staging systems for SCC “led us to overtreat nonaggressive disease and undertreat aggressive disease. I think we have the responsibility to lead the charge to having a more sophisticated approach.” For example, patients whose tumors were staged T2 in the American Joint Commission on Cancer (AJCC) 7 classification system were most likely to have poor outcomes – in part because so few tumors were staged higher – which meant AJCC 7 didn’t provide adequate differentiation for useful risk prognostication.

A group of researchers at the Brigham and Women’s Hospital (BWH), Boston, “came up with a better system to better differentiate those T2 tumors into a high-risk and a low-risk subtype,” according to Dr. Patel.

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