Risk of Diabetes Mellitus after Radiotherapy for Gastric Mucosa-Associated Lymphoid Tissue Lymphoma.

The long-term effect of radiation on pancreas has been mostly studied for pediatric patients with the lack of individual radiation dosimetric data. The purpose of this study was to investigate the effect of radiotherapy (RT) on the risk of newly developed diabetes mellitus (DM) in patients with gastric mucosa-associated lymphoid tissue lymphoma (GML) using individual radiation dosimetric analysis. We retrospectively reviewed 225 patients without history of DM who received curative aim treatment for stage IE GML between August 2007 and June 2020. Involved site RT to the whole stomach was delivered in 83 patients (36.9%). The pancreas was delineated in each patient's computerized tomography scan for dosimetric analysis. At a median follow-up time of 49.0 months (range, 3.0-155.3 months), the 3-year cumulative incidence of DM was 3.9% in all patients, and 7.9% and 1.6% in patients who received and did not receive RT, respectively (p=0.009). The mean pancreatic dose (D mean) was independently associated with DM (p=0.027). As a result of recursive partitioning analysis, patients were classified into low (D mean <21 Gy), intermediate (D mean ≥21 Gy and BMI <27.0kg/m2), and high-risk groups (D mean ≥21 Gy and BMI ≥27.0kg/m2) with 5-year DM incidence of 1.5%, 6.3%, and 54.3%, respectively (p<0.001). Our results indicate that incidental irradiation to the pancreas can increase the risk of DM, which was dependent on pancreas D mean. In addition, not only reducing pancreas D mean but also controlling BMI may need to be combined to effectively prevent DM after RT. [ABSTRACT FROM AUTHOR]