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Abdominal radiation dose linked to diabetes risk among childhood cancer survivors
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Higher pancreatic tail radiation doses during childhood cancer treatment appeared associated with higher risk for diabetes later in life, according to results of a prospective, survey-based study published in Journal of the National Cancer Institute.
“Due to improved therapies and supportive care for childhood cancer, 5-year survival rates now exceed 80%,” Danielle Novetsky Friedman, MD, MS, pediatrician at Memorial Sloan Kettering Cancer Center, and colleagues wrote. “Improved survival, however, has led to increased recognition of survivors’ excess risk of morbidity and mortality due to treatment-related late effects.”
Previous studies showed that survivors of childhood cancer who received abdominal radiation have an increased risk for diabetes. However, the relationship between risk and radiation dose had not been established.
In this study, Friedman and colleagues evaluated 20,762 5-year childhood cancer survivors (median age, 31.6 years; range, 10.2-58.3) — including 4,568 who were exposed to abdominal radiation — and 4,853 siblings.
The researchers used data from radiation records to estimate the maximum dose of radiation to the abdomen, in addition to calculating pancreas-specific dose metrics.
Results showed 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 median age of 30 years (range, 3-53), whereas 1.2% (95% CI, 1-1.3) of survivors who did not receive abdominal radiation reported having diabetes at median age of 28 years (range, 0-54).
Among siblings, 0.8% (95% CI, 0.6-1.1) reported having diabetes at median age of 34 years (range, 4-53).
Survivors who received abdominal radiation appeared 2.92 times (95% CI, 2.02-4.23) more likely than siblings to develop diabetes, and 1.6 times (95% CI, 1.24-2.05) more likely than survivors with no abdominal radiation exposure.
In addition, older age (RR per 10 years = 2.11; 95% CI, 1.7-2.62), higher BMI (RR for BMI > 30 = 5; 95% CI, 3.19-7.83) and higher mean pancreatic tail dose all appeared associated with higher risk for diabetes among survivors treated with abdominal radiation.
Among survivors aged 21 to 30 years, incidence of diabetes was 1.3% (95% CI, 1-1.9) for those treated with abdominal radiation, 0.8% (95% CI, 0.6-1) for those not treated with abdominal radiation and 0.4% (95% CI, 0.2-0.8) for siblings.
Among survivors aged older than 40 years, the incidence of diabetes was 4.6% (95% CI, 3.3-6.4) for those treated with abdominal radiation, 3.1% (95% CI, 2.3-4.1) for those not treated with abdominal radiation and 2.1% (95% CI, 1.4-3.2) for siblings.
Diabetes cases were classified by patients’ self-reporting without verification by a treating physician, which served as a potential study limitation.
“Among those treated with abdominal radiation, we found a linear dose-response relationship between diabetes risk and higher pancreatic tail dose, but not with other dosimetric or volumetric variables,” Freidman and colleagues wrote. “Younger age at cancer diagnosis was a key risk factor ... and should be factored into risk-based screening practices for this cohort. We have also shown that both simple and sophisticated models may be used to identify survivors at highest risk for diabetes after abdominal radiation.” – by John DeRosier
Disclosures: The authors report no relevant financial disclosures.
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