Risks of leukemias increase after radiation treatment, including RAI, which is frequently used to treat WDTC. However, the risk of AML following RAI treatment in WDTC survivors has not been characterized.
In a population-based study, we queried all 18 Surveillance Epidemiology and End Results registries for WDTC cases treated with surgery or surgery followed by RAI. We assessed the risk dynamics of developing AML in WDTC patients and its association with RAI. We also studied the clinical outcome of AML that occurred after WDTC diagnoses in case-control studies.
Of 148,215 WDTC patients identified between 1973-2014, 55% received surgery alone and 45% received surgery and RAI. After a median 4.3 person years of follow up (IQR, 1.9-7.4), 44 patients developed AML after surgery alone for WDTC and 56 patients developed AML after surgery and RAI. Compared to the background rates in the general population, patients treated with surgery and RAI had an increased risk of developing AML that peaked within the first three years after RAI treatment (RR: 5.6, 95% CI: 3.8-8.1, P < 0.0001). After correction for sex and WDTC tumor size in a multivariate analysis, patient age (HR: 1.03, 95% CI: 1.02-1.05, P < 0.001), WDTC tumor stage (HR: 1.36, 95% CI: 1.04-1.79, P = 0.03) and RAI treatment for WDTC as compared with thyroidectomy alone (HR: 1.38, 95% CI: 1.09-1.75, P = 0.007) were independent prognostic factors for AML development. WDTC patients that developed AML after surgery and RAI had a truncated survival as compared with matched WDTC control patients that did not develop AML (median OS: 7.5 years vs. 24.4 years, P < 0.0001). Finally, patients that were diagnosed with AML after RAI treatment for WDTC had a worse prognosis than patients with AML that occurred spontaneously (median OS: 1.2 years vs. 3.5 years, P = 0.004).
RAI treatment is associated with an increased risk of developing AML in WDTC survivors. RAI-related AML has a poor survival, similarly to t-AML that arises after radiotherapy or chemotherapy. Considering young patient ages at WDTC diagnosis and high survival rates, the rates of AML in WDTC survivors are likely to continue to rise.
Clinical trial identification
Legal entity responsible for the study
American Cancer Society
All authors have declared no conflicts of interest.