Letter by Jin-shan and Xue-bin Regarding Article, “Pericarditis as a Marker of Occult Cancer and a Prognostic Factor for Cancer Mortality”

We read with great interest the article by Sgaard and colleagues 1 about pericarditis as a marker of occult cancer. The article indicates that pericarditis may be a marker of occult lung and breast cancer, as well as hematologic and unspecified metastatic cancers, and it is associated with worse survival among patients with certain cancers. We have several questions about this article. First, pericarditis is the most common disease of the pericardium, with an annual incidence rate of 30 per 100 000 people; the causes include infection, trauma, autoimmune disease, and cancer. Considering economic and patient-related costs, performing extended screening such as whole-body scans for high-risk patients with cancer is reasonable. Other than old age and pericardial effusion, are there any other characteristics used as risk factors for pericarditis with cancer? Second, extended screening such as whole-body scans may increase patients' exposure to radiation and anxiety associated with the diagnostic workup. Are there special signs of computed tomography or magnetic resonance imaging examinations of patients of pericarditis with cancer to make the diagnosis simpler? What about positron emission tomography-computed tomography? Is it useful for increasing the diagnostic rate and lowering radiation exposure? Last, cancer-related pericarditis is most commonly caused by metastasis. However, in this research, among the patients with pericarditis, 40% have localized cancer, 36% have metastatic cancer, and 24% have an unknown or missing cancer stage. The corresponding proportions for patients without pericarditis are 42%, 37%, and 22%, respectively. Why is there no difference in the proportions of metastatic patients between them?