Pneumopericardium is a relatively rare entity mostly described in the literature as a result of causes such as penetrating/blunt trauma and iatrogenic causes during cardiothoracic procedures. We are presenting a case of pneumopericardium as a complication of progressed gastroesophageal junction tumor along with a literature review of all cancer-related pneumopericardium cases reported in the last decade. We present the case of a 65-year-old male with a past medical history significant for locally advanced gastroesophageal junction adenocarcinoma who presented to the hospital with complaints of shortness of breath and fever. A chest X-ray showed an intact esophageal stent along with radiolucency around the cardiac silhouette which suggested pneumopericardium. Computed tomography scan of the chest confirmed the presence of pneumopericardium in posterior pericardium with foci of gas above the esophageal stent likely to be communicating with the pericardium. An echocardiogram was obtained which showed no signs of tamponade. Given the advanced nature of the disease we applied a conservative management given that the pneumopericardium was deemed to be small with no tamponade. Goals of care were discussed with the patient and his family and the patient opted for comfort care measures. This case report prompted us to perform an extensive literature review of cancer-related pneumopericardium from 2008 to 2019. We found 11 cases where it was reported secondary to malignancies of different kinds. Our aim is to compile a review for clinicians to view varied presentations and better direct therapy dependent on the individual case and clinical presentation in patients with cancer-related pneumopericardium. Moreover, although pneumopericardium is rare, it should be considered in differential diagnosis in patients presenting with shortness of breath or chest pain especially with cancers involving the cardiothoracic region.