Increased risk of second primary malignancy in thyroid cancer patients treated with radioactive iodine | J Natl Cancer Inst
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This study found an increased risk of second primary malignancy (SPM) for thyroid cancer patients treated with radioactive iodine (RAI), especially with cumulative RAI doses over 150 mCi.
Among 20,235 patients with thyroid cancer, 692 cases of SPM were identified.
Standardized incidence ratio (SIR) for any SPM was 1.41 (95% confidence interval [CI]=1.31 to 1.52).
Higher statistically significantly SIR was seen in leukemia (2.74), non-Hodgkin's lymphoma (2.38), and prostate (2.30), lung and mediastinum (1.93), pancreas (1.83), kidney (1.81), breast (1.48), and colon-rectum (1.31) cancers.
Cumulative RAI dose (per 30 mCi increase) conferred a strong risk for SPM (adjusted hazard ratio [aHR]=1.01, 95% CI=1.01 to 1.02, P<.001) and leukemia (aHR=1.03, 95% CI=1.02 to 1.04, P<.001).
Cumulative RAI dose 150 mCi possessed a statistically significant risk for all cancer combined (aHR=1.30) and leukem...