SITC Immunotherapy for the Treatment of Nonmelanoma Skin Cancer Guideline Summary

Diagnosis, workup, and initial staging for MCC

Histopathological diagnosis of MCC should include hematoxylin and eosin (H&E) and IHC with evaluation by a pathologist with experience in the diagnosis of skin cancers, when feasible.
For patients with MCC, multidisciplinary care team management is optimal.
Baseline imaging should be considered in all patients with MCC for the detection of metastatic disease (LE:4).
Baseline MCPyV oncoprotein serology testing (eg, AMERK) should be considered, as this has implications for surveillance (LE:3).
If, by clinical examination or imaging, a patient is suspected of having nodal or distant metastatic disease, a biopsy should be performed for histological confirmation (LE:3).
If imaging and clinical evaluation are negative for metastatic disease, patients should be considered for sentinel lymph node biopsy for staging (LE:1).

For patients with metastatic, recurrent, or locally advanced MCC that is not amenable to curative surgery or radiation and for whom no contraindications to immunotherapy are present, first-line therapy with an approved anti-PD-(L)1 ICI is recommended (LE:2).
For patients with MCC who experience disease progression while on anti-PD-(L)1 immunotherapy, therapeutic options are limited and include the addition of an anti-CTLA-4 antibody to anti-PD-(L)1 therapy, clinical trials, or chemotherapy. Switching treatments from one anti-PD-(L)1 antibody to another anti-PD-(L)1 antibody is unlikely to be beneficial.
While responses to PD-(L)1 blockade are frequent and generally durable, disease progression may occur in a subset of responders, and hence, continued surveillance for MCC progression is warranted.
For patients with MCC being treated with anti-PD-(L)1 ICIs, there are no validated biomarkers to predict benefit (including MCPyV viral status or PD-L1 expression).

Immunotherapy for the Treatment of Nonmelanoma Skin Cancer