Discussion
This patient underwent a resection of her trachea in 2017 for reportedly HPV positive squamous cell carcinoma (SCC). She was then lost to follow-up and received no treatment up until 2020, when she reappeared with stridor and a significantly obstructing tracheal mass just below the thoracic inlet, with apparent transmural invasion and involvement of at least the esophageal adventitia. In turn, mechanical ventilation could not be performed.
This SCC was a typical pattern HPV tumor with clear confirmation by diffuse nuclear cytoplasmic p16 immunohistochemical positivity. The PD-L1 for Keytruda (Pembrolizumab) was positive with a combined positive score (CPS) of 15. The PD-L1 for Opdivo was also positive. Pembrolizumab is a selective humanized IgG4 kappa monoclonal antibody that inhibits the programmed death-1 (PD-1) receptor, an integral component of immune checkpoint regulation in the tumor microenvironment9. The PD‑L1 and PD‑L2 ligands on tumors can bind with PD-1 receptors on T cells to inactivate them9. Pembrolizumab binds to the PD-1 receptor and blocks its interaction with PD‑L1 and PD‑L2, which helps to restore the immune response9. The drug is currently approved by the Food and Drug Administration (FDA) for the treatment of metastatic or unresectable, recurrent head and neck SCC whose tumors express PD-L1 [CPS >=1], with disease progression on or after platinum-containing chemotherapy. It has also been approved for treatment of advanced melanoma and metastatic squamous and nonsquamous non-small cell lung cancer (NSCLC)9. Ultimately, according to a 2015 study by Bowman, the greatest value to be derived from tracking PD-L1 testing is the ability to link test results to treatment decisions10.
As of May 15, there has been no recurrence of the symptoms since surgery, and imaging shows a clear and patent trachea. The implications of PD-L1 staining in this patient and subsequent choice of chemotherapy will continue to be evaluated throughout the patient follow-up period.
Regarding the decision to not use any form of anticoagulation during the procedure, blood loss was minimal, less than 10 mL. There also were no thrombotic or hemorrhagic complications during or after this surgery. Based off of these positive results, we recommend that anticoagulation and its possible benefits and negative side effects be considered in full effect for any procedure dealing with a small opening in a head and neck procedure. For our group, the potentially catastrophic mid-procedure outcomes from use of anticoagulation caused us to decide against its use, especially given the very small opening through which the tracheal procedure occurred. In sum, the ultimate fear for our group was that intraoperative bleeding in the small operative space would lead to an inability to continue and successfully complete the operation. With limited visualization, the resection of 90 percent of the tracheal mass would not have been possible. As mentioned above for the PD-L1 staining, thrombotic and hemorrhagic events will continue to be at forefront of our minds during this postoperative and follow-up period. We will continue to monitor the patient and check for any changes or discrepancies in her CBC, BMP, and clotting factors.