Background: Under the current epidemic of the coronavirus disease of 2019 (COVID-19), there is a need to distinguish the differences between the laboratory examinations of COVID-19-infected patients, tumor patients with fever, and those with normal fever patients. We aimed to investigate the temperature of tumor patients with different tumor burdens, stages, and cancer types. Methods: We recruited 3 groups of patients to this study: fever patients with malignant tumors, ordinary fever patients, and confirmed cases of COVID-19, with 31, 55, and 28 cases in each group, respectively. Results: The levels of leukocytes and neutrophils were the highest among non-tumor patients, and the count of COVID-19 was the lowest, with a P value of 0.000. Among the leukocytosis group, non-tumor patients had the highest proportion (43.6%), while that of COVID-19 was only 3.6% (P=0.000). Similarly, there were significant differences in the grading of neutrophils, where most of the infected patients were in the normal group and the P value was 0.000. The lymphocyte count of the tumor group was significantly reduced, with an average of (0.97 +/- 0.66) x109/L (P=0.004). In the lymphocyte grades, most of the infected patients were the normal group (71.4%), while tumor patients in the lymphocytopenia group accounted for 63.1% (P=0.006). There were also significant differences in the neutrophil to lymphocyte ratio (NLR) (P=0.006). There was a significant difference in temperature between different tumor burden groups (P=0.014). Conclusions: The normal fever group had the highest count of leukocyte and neutrophils, whereas the infected group had the lowest relative count. The NLR was the lowest in the infected group. The NLR was higher in the bigger tumor load group.