492. TYPES AND INCIDENCE OF POSTOPERATIVE ANEMIA AFTER ONCOLOGICAL ESOPHAGECTOMY AND GASTRECTOMY

According to current literature, anemias that develop after oncological esophageal and gastric resections are classified as deficiency anemias. Due to the surgery-related changes in the mechanical and biochemical conditions of the upper gastrointestinal tract, there is an alteration in the processing and absorption of hematopoietic-relevant vitamins and trace elements like iron, vitamin B6, vitamin B12, folic acid, copper and essential amino acids in the postoperative phase. Between January 2015 and December 2019, 232 patients underwent a (sub)total gastrectomy or esophagectomy at our center. In this monocentric retrospective analysis of prospectively collected follow-up data, 157 patients were included after applying the exclusion criteria: Age below 18, primary bone marrow disease, hereditary forms of anemia, postoperative tumor recurrence and R1/R2 situation. 103 patients (=66%) belonged to the esophagectomy group and 54 patients (=34%) to the (sub)total gastrectomy group. Preoperatively and three, six, twelve, 18, and 24 months postoperatively the following laboratory parameters were collected and descriptively analyzed: Hemoglobin, MCV, MCH, serum iron, ferritin, transferrin, and vitamin B12. Two years after the oncological resection 28% of patients with esophagectomy, EE, and 48% of patients with (sub)total gastric resection, (S)GE, show anemia. Normocytic anemia was the dominant type. The MCV distribution of anemic patients in the EE group was as follows: 3% microcytic, 77% normocytic, and 20% macrocytic. The anemic patients in the (S)GE group show the following MCV distribution: 16% microcytic, 81% normocytic, and 3% macrocytic. The (S)GE collective has more anemic patients in percentage terms than the EE collective throughout the whole follow-up period. This difference is significant at the 12th (p = 0.032) and 18th-month (p = 0.023) postoperative follow-up. A high percentage of patients with oncological resection of the upper gastrointestinal tract have a relevant postoperative anemia. The known postoperative iron and vitamin deficiencies, that would be associated with microcytic hypochromic and macrocytic hyperchromic anemia, are not the relevant causes for this anemia as it is predominantly a normocytic form. Normocytic anemia is an indication for an anemia of chronic disease. The reason for the predominance of normocytic anemia is not specifically known.