Background: Survivors of childhood cancer with history of radiation therapy (RT) to the head/neck/chest are at increased risk for stroke. Children’s Oncology Group Guidelines recommend carotid ultrasound (CU) when clinically indicated or 10 years after RT ≥ 40Gy to the neck. Yet, the use of CU has not been previously described. Methods: 8,693 survivors of childhood cancer (median age at diagnosis 8.0 years, range 0-20; median age at evaluation 37.4, range 18-65) diagnosed between 1970-1999 were asked if they had ever had a CU. Cardiovascular disease (CVD) was defined as any of the following: stroke, congestive heart failure, hypertension, myocardial infarction, coronary heart disease, or arrythmia. Prevalence ratios (PR) were calculated; age and sex-adjusted multivariable Poisson regression models evaluated factors associated with CU. Results: 4.9% (427) of survivors had a history of stroke and 28% (2,442) had a history of any CVD. Of these, 40.0% (171) with a history of stroke and 28.6% (748) with any CVD had CU. Comparatively, 14.6% (1,404) without a stroke and 11.1% (798) without any CVD had a CU (both p<0.0001 vs those with condition). Among survivors without CVD, having seen only a primary care physician was not associated with CU (PR 0.84 95% CI 0.58-1.25, p = 0.36), while seeing a cancer specialist (+/- a primary care physician) (PR 1.83 95% CI 1.23-2.79, p = 0.036) was associated with increased likelihood of CU compared to seeing neither. Survivors who had had other surveillance studies, including a colonoscopy (PR 1.76 95% CI 1.44-2.17, p<0.0001), skin cancer exam (PR 1.62 95% CI 1.30-2.03, p=0.0002), or mammogram (PR 2.06 95%CI 1.42-3.07, p<0.0001) were more likely to have a carotid ultrasound, compared to those without that test. Having a history of anthracyclines or RT to the neck were associated with higher prevalence of CU, with RT to the neck exhibiting a dose-response relationship (Table). Conclusions: CU was more common among survivors with a history of stroke or other CVD event. In those without CVD, CU use was associated with anthracyclines and RT dose exposures and with care provided by a cancer specialist. A high proportion (70%) of survivors who received >40Gy RT to the neck have never had a CU, suggesting that greater awareness of guidelines is needed.

*Adjusted for attained age and sex.