Abstract
A 40-year-old woman was diagnosed with gastric cancer and underwent laparoscopically assisted distal gastrectomy. During postoperative adjuvant chemotherapy, she exhibited a sharp rise in CA19-9 in a blood sample test about 4 months after surgery. Imaging did not show findings related to high CA19-9 levels, such as gastric cancer recurrence, other malignant diseases, or biliopancreatic abnormalities, and she was therefore placed under follow-up, but general malaise and dipsia intensified at about 8 months after surgery. Various tests revealed the presence of significant hyperglycemia resulting from type 1 diabetes. Later, as glycemic control improved, CA19-9 levels also normalized. As of the time of writing, 14 months since surgery, she has not shown a return to elevated tumor marker levels. Hyperglycemia is known to be one cause of a rise in CA19-9, and elevated CA19-9 levels after gastrectomy, which is prone to cause changes in blood sugar levels, require appropriate searching and treatment while also bearing the possibility of hyperglycemia-related false-positive results in mind.
