**14. Diabetes mellitus**

The increased risk of diabetes mellitus (DM) from abdominal RT has been increasingly recognized over the past two decades, the pathophysiology of which is not completely clear, but likely related to the damage of insulin-producing ß cells concentrated in the tail of the pancreas [57]. In a study of Scandinavian childhood cancer survivors, the relative risks for DM were significantly increased in patients with WT, with an observed-to-expected first hospitalizations for DM of 2.9 [58]. A report from the Childhood Cancer Survivor Study demonstrated that WT survivors were more likely to be diabetic than siblings (RR 3.77), and this association remained significant when adjusted for body mass index. Among cancer survivors treated with abdominal RT, greater attained age, higher body mass index and increasing pancreatic tail dose were associated with increased DM risk [59]. In addition, a statistically significant interaction was noted between younger age at cancer diagnosis and mean pancreatic tail dose, with greater differences in DM risk noted among those diagnosed at the youngest ages. Among survivors diagnosed at age 5 years, relative risk of DM was 2.98 after a mean pancreatic dose of 10–19.9 Gy, 3.62, after 20–29.9 Gy, and 4.66 after 30+ Gy, with reference group being 0.1–9.9 Gy [59].
