Radiation Dose and Volume Increase Diabetes Risk

A study published in the Journal of the National Cancer Institute found that childhood cancer survivors who received higher pancreatic tail doses of abdominal radiation at a younger age had an increased risk of diabetes later in life.

In this prospective, survey-based study, researchers assessed 20,762 five-year survivors (median age, 31.6 years; range, 10.2-58.3 years) of childhood cancer, 4,568 of whom were exposed to abdominal radiation, as well as 4,853 siblings. Researchers used radiation records to estimate maximum dose to abdomen, mean doses for whole pancreas, pancreatic head, body, tail, and percent pancreas volume receiving ≥10, ≥20, and ≥30 Gy.

There were 389 cases of diabetes among all survivors and 53 cases among siblings. Among the survivors treated with abdominal radiation, 2.3% (95% CI 1.9-2.8) reported having diabetes at a median age of 30 years (range, 3-53 years), while 1.2% (95% CI, 1-1.3) of survivors who did not receive abdominal radiation reported having diabetes at a median age of 28 years (range, 0-54 years).

Survivors who were exposed to abdominal radiation were 2.92-fold more likely than siblings (95% CI, 2.02-4.23) and 1.60-fold more likely than survivors who were not exposed to abdominal radiation (95% CI, 1.24-2.05) to develop diabetes.

Among survivors treated with abdominal radiation, the following were associated with increased risk of diabetes:

  • Greater attained age (relative risk [RR] per 10 years, 2.11; 95% CI, 1.70-2.62)
  • Higher body mass index (BMI; RR at a BMI ≥30 kg/m2, 5.00; 95% CI, 3.19-7.83 with reference to BMI 18.5-24.9 kg/m2)
  • Increasing pancreatic tail dose

Researchers also observed an interaction between younger age at cancer diagnosis and pancreatic tail dose with much higher diabetes risk associated with increasing pancreatic tail dose among those diagnosed at the youngest ages (P<0.001).

Radiation dose and volume to other regions of the pancreas were not statistically significantly associated with this risk.

“Targeted interventions are needed to improve cardiometabolic health among those at highest risk,” the researchers concluded.

A limitation of the study is the use of self-reporting of diabetes cases without confirmation by a treating physician, which poses a risk for bias. Read more