Systemic Treatment of Metastatic Cutaneous Squamous Cell Carcinoma - Episode 2

Updated Diagnosis and AJCC Staging Guidelines in CSCC

Michael R. Migden, MD:The patients that are at highest risk for developing advanced forms of cutaneous squamous cell carcinoma would be those where prior surgeries had failed; so 2 or more prior surgeries. Those where the biopsies show perineural invasion, especially nerves that are greater than 0.1 mm, those with the subtype of histology being moderately to poorly differentiated; so those are more aggressive cancers; those where the width of the tumor is 2 cm or larger and those where the invasion depth on histology is 2 mm or greater.

The workup for advanced cutaneous squamous cell carcinoma, of course, depends on the specific problem at hand. If you know you have perineural invasion, the thought is that the MRI [magnetic resonance imaging] is a better tool for looking at the extent of perineural invasion, which is often a big determinant on how serious the disease is, and also what treatment options are available. Patients may have a hard time holding still for a slow study, like an MRI, and then they have the artifact if the patient can’t remain still. CT [computed tomography] is a generally faster study with a more uniform accuracy because it’s not dependent on whether the patient can remain still. Certain tissues show up better in MRI, certain tissues show up better with CT. It’s a judgment depending on the biopsy results and the location of the tumor.

So, let’s talk about how to communicate the extent of disease and the areas of involvement. My preferred way to look at this is the way the studies are designed, and that’s either having contiguous, which would be your locally advanced subdivision of advanced, or metastatic, which is your discontiguous subdivision of the term advanced. When we have discontiguous disease, otherwise known as metastatic disease, that can be locoregional such as neck nodes, or parotid nodes, or distant, such as organ involvement or bony involvement. I prefer to think about this disease as either contiguous or discontiguous disease, ie, locally advanced versus metastatic disease.

The staging criteria, the AJCC (American Joint Committee on Cancer) is a work-in-progress. We went from 7th edition to 8th edition, in attempt to try and improve it. The outcome of the changes has not had time to be measured yet, so we don’t know if the 8th edition of AJCC correlates with known outcomes from treatment of disease. I like the Brigham and Women’s [Hospital] staging criteria because it attempts to incorporate as many different risk factors, features, and staging. We went through some of these already, such as the 2 mm or greater depth, 2 cm or greater width, the poorly differentiated tumor, the perineural tumor. So, we don’t know yet how well AJCC 8 will perform. I like Brigham and Women’s, and if I had to choose, I would stick with the way the studies are designed, which would be locally advanced or metastatic disease. It’s more important for a TNM [TNM Staging System], or disease stage, if you’re trying to communicate for surgery and/or radiation, in my opinion, than it is for systemic therapy, especially immunotherapy. And, in that case, again, I’d rather have locally advanced or metastatic as my assessment of the disease.

Transcript edited for clarity.