Anaplastic thyroid cancer (ATC) is considered to be one of the most virulent, treatment-refractory malignancies. Recent molecular insights into the biology of thyroid cancer have transformed ATC management, and BRAF/MEK targeted therapy is now incorporated into guideline-based multidisciplinary care. We report visceral perforation in the setting of an extreme response to such therapy in a patient with ATC. Molecularly targeted therapy afforded a dramatic but life-threatening response to treatment. This report highlights the complexities of care for the patient and treating clinicians.

Background: Gastroesophageal cancers (GECs) carry considerable morbidity and mortality, and demonstrate geographical histological variances in addition to molecular heterogeneity. Consequently, the immunogenicity of the different subtypes, which can predict the likelihood of immunotherapy response, can vary. Immune checkpoint inhibitor (ICI) therapy has transformed the treatment of many cancer types over the past decade but has been slower to gain a foothold in the treatment paradigm of GECs. Methods: This article reviews the existing evidence and use approvals for immunotherapies and immune-based treatments in GECs, in the neoadjuvant, adjuvant and metastatic disease settings. The challenges of and limitations to ICI application in current clinical practice are examined. Ongoing clinical trials and future directions of research are also considered. Conclusion: ICI therapy has become an established treatment option within GECs, both perioperatively and in advanced disease. However, nuances in terms of its use are not yet fully understood. Ongoing research proposes to broaden the application of immunotherapies in GECs with the potential to continue to improve outcomes.