Delphi method identifies a role for imaging in the treatment of cutaneous squamous cell carcinoma

Most people with cutaneous squamous cell carcinoma (CSCC) are successfully treated with surgery. But most is not all. CSCC after surgery can be aggressive, spread to lymph nodes, metastasize and, in the most severe cases, be deadly. The American Cancer Society estimates that between 2,000 and 8,000 people die each year from either basal or CSCC with most of those deaths coming from CSCC. The estimate has a wide range partly basal and CSCC are not tracked in cancer registries

Some research has suggested that imaging CSCC could help with early detection of recurrence and be useful in guiding initial treatment choices. But imaging is not part of routine clinical practice, and guidelines are vague on the topic.

To fill that void, 54 experts participated in a modified three-step Delphi process to arrive at a consensus about how imaging might fit into the care of CSCC and which imaging technology should be used. Fifteen of 45 experts completed all three rounds of consensus-building were dermatologists. The others were medical oncologists and radiation oncologists. radiologists, surgeons and otolaryngologists. All had a documented background showing expertise in CSCC. Consensus was defined as 80% agreement or greater agreement, and near consensus as 70% to 79% agreement.

The results of the process, which were published earlier this month in JAMA Dermatology, showed agreement on using imaging for staging and surveillance for CSCC when there is at least a 15% predicted risk of nodal metastasis. Consensus or near-consensus was also reached in favor of staging and surveillance imaging when there is a possibility of metastasis, bone invasion, invasion beyond subcutaneous fat, large-caliber nerve invasion or if the CSCC tumor has a diameter of four centimeters or larger.

Consensus in favor of incorporating imaging into CSCC care was also reached when the CSCC cells were poorly differentiated and other conditions were met, such as the tumor having a diameter of two centimeters or larger or the presence of ymphovascular invasion plus subcutaneous fat invasion.

The experts did not reach consensus for imaging in several scenarios, including when the patient had limited life expectancy, when the tumors were at lower stage and considered definitive for radiotherapy.

As for the type of imaging, the experts favored computed tomography (CT) imaging with intravenous contrast for nodal staging and surveillance. Positron emission tomography (PET) in combination with CT imaging was the preferred method for patients with underlying hematologic cancers. For patients for whom CT contrast is contraindicated, the most favored choice was PET-CT followed by ultrasonography, CT without contrast and magnetic resonance imaging. Among the nine radiologists who participated in the Delphi process, two indicated that they currently performed ultrasonography for nodal staging, yet five reported feeling comfortable interpreting ultrasonography to evaluate for metastatic skin cancer in nodal basins.

The panelists were largely in agreement that surveillance imaging should be done at least every six months during the first year and second years after surgery and then annually by the third year.

Corresponding author Emily S. Ruiz, M.D., M.P.H., the academic director of the Mohs and Dermatologic Surgery Center at Brigham and Women’s Hospital in Boston and an associate professor at Harvard Medical School, and her colleagues said that their ambitions for Delphi process results were that they “serve as a framework to help standardize staging and surveillance imaging” for CSCC. They noted in the introduction of the JAMA Dermatology article that the current National Comprehensive Cancer Network guidelines recommendations are broach, advising clinicians “to discuss and consider radiologic imaging” and to consider using imaging for surveillance “if clinical examination is insufficient.”

While the topic at hand was imaging, Ruiz and her colleagues also mentioned the importance of the traditional ways of assessing CSCC. “Although this Delphi focused on imaging use, careful examination of the primary site and draining lymph node basin remains a cornerstone to surveillance, and some recurrences, especially in-transit metastasis, are more likely to be identified on physical examination,” they wrote.