A high ferritin of 1000 is not necessarily cancer; the possibility exists that it is cancer. Ferritin is a soluble tissue protein that stores iron in the body, and the concentration of plasma ferritin is proportional to the iron stored in the body. Plasma ferritin concentration is proportional to the iron stored in the body. The reference range is 80~130ng/mL for men, 35~55ng/mL for women (premenopausal), and 50~120ng/mL (postmenopausal). Ferritin 1000ng/mL, which is an increase in ferritin, is commonly seen in excessive iron loading of the body due to repeated multiple blood transfusions, iron therapy, hemoglobin deposition disorder, etc.. It can also be seen in hemolytic anemia, pernicious anemia, cancer anemia, and primary liver cancer, cirrhosis, renal insufficiency and inflammation, early myocardial infarction. It can also be increased when there is metastasis in gastric cancer, rectal cancer, esophageal cancer, nasopharyngeal cancer and breast cancer. Therefore, when ferritin is high 1000ng/mL, it is not necessarily cancer, and it is necessary to further improve the examination under the guidance of the doctor to clarify the cause of the disease and follow the doctor’s instructions for treatment.