The advent of immune checkpoint inhibitors (ICIs) in the field of oncology has improved the outcome response rate for a variety of neoplastic pathologies with improved cellular specificity that lacks the traditional adverse effects associated with chemotherapy. However, ICIs are not without adverse associations, and a growing concern for modern clinicians is the balancing of interests that most occur to minimize these adverse effects while also improving patients’ conditions from an oncologic perspective. This case presents a 69-year-old man who developed multiple episodes of significant pericardial effusion while receiving infusions of pembrolizumab for stage III-A adenocarcinoma for which he underwent a pericardiostomy procedure. Given the positive response of this immunotherapy on disease progression, the decision was made to continue the administration of pembrolizumab following the pericardiostomy with the plan of using serial echocardiography studies to monitor for the presence of clinically significant pericardial effusion in the future. In this way, the patient will still be able to receive optimal treatment for his advanced cancer while preserving adequate cardiac function.