Obesity and Risk for Second Malignant Neoplasms in Childhood Cancer Survivors: A Case-Control Study Utilizing the California Cancer Registry.

backgroundObesity is a known modifiable risk factor associated with adverse outcomes in children with cancer. We sought to determine whether obesity during childhood cancer treatment increases risk for second malignant neoplasms (SMN).

methodsIn this case-control study, cases (with SMN) and controls (with a single-primary cancer) were selected from the California Cancer Registry who had primary cancer diagnosed <21 years treated at Children's Hospital Los Angeles between 1988 and 2014. Controls were matched 3:1 to cases at the registry level by clinical factors. Medical records were abstracted for cancer treatment exposures, cancer predisposition syndrome, body mass index (BMI), BMI Z-score, and BMI category at diagnosis and end of therapy (EOT).

resultsA total of 59 cases and 130 controls were included. Median age at primary cancer diagnosis was 6 years, 64.5% were male, median time from primary cancer to SMN was 7.5 years, and 31.7% were obese or overweight. In matched multivariable analyses, there were elevated but nonsignificant associations between SMN and higher BMI Z-score at diagnosis [OR 1.27 (0.99-1.63)] and higher BMI categories at diagnosis [adjusted OR (aOR) overweight, 1.25 (0.55-2.52); aOR obese, 2.51 (1.00-6.29)]. There was a significantly increased risk for SMN among patients who were obese at both diagnosis and EOT [aOR, 4.44 (1.37-14.34)].

conclusionsThis study suggests that obesity during childhood cancer treatment may be associated with increased risk for SMNs, particularly among those obese throughout therapy. IMPACT: Additional studies to confirm these findings and to develop interventions have the potential to impact SMN development in children with cancer.