Second primary malignancy risk after radioiodine treatment for thyroid cancer: A systematic review and meta-analysis

Division of Endocrinology and Department of Medicine, University Health Network, Toronto, Ontario, Canada.
Thyroid: official journal of the American Thyroid Association (Impact Factor: 3.84). 04/2009; 19(5):451-7. DOI: 10.1089/thy.2008.0392
Source: PubMed

ABSTRACT The risk of second primary malignancies (SPMs) associated with cancer therapies is an important concern of thyroid cancer survivors and physicians. Our objective was to determine if the risk of SPMs is increased in individuals with thyroid cancer treated with radioactive iodine (RAI), compared to those not treated with RAI.
We performed a systematic review of the literature and meta-analysis. Two independent reviewers screened citations and reviewed full-text papers. If not reported by the primary authors, the relative risk (RR) of SPMs was calculated by dividing the standardized incidence ratio of SPM in individuals with thyroid cancer treated with RAI compared to those not treated with RAI (with associated 95% confidence intervals [CI]). The natural logarithms of RRs of respective SPMs, weighted by the inverse of the variance, were pooled using fixed effects models and the exponential of the results was reported.
Two multi-center studies (one from Europe and the other from North America) were included in this review. The RR of SPMs in thyroid cancer survivors treated with RAI was significantly increased at 1.19 (95% confidence interval [CI] 1.04, 1.36, p = 0.010), relative to thyroid cancer survivors not treated with RAI (data from 16,502 individuals), using a minimum latency period of 2 to 3 years after thyroid cancer diagnosis. The RR of leukemia was also significantly increased in thyroid cancer survivors treated with RAI, with an RR of 2.5 (95% CI 1.13, 5.53, p = 0.024). We did not observe a significantly increased risk of the following cancers related to prior RAI treatment: bladder, breast, central nervous system, colon and rectum, digestive tract, stomach, pancreas, kidney (and renal pelvis), lung, or melanoma of skin.
The risk of SPMs in thyroid cancer survivors treated with RAI is slightly increased compared to thyroid cancer survivors not treated with RAI.

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    • "Typically, acute toxicity resolves rapidly. Patients also can develop chronic toxicity from I-131, such as xerostomia and subsequent dental caries [30], lacrimal duct dysfunction [31], chronic sialoadenitis [32], and rarely second malignancy [33]. I-131 toxicity is dose dependent; patients receiving higher activities of I-131 (>150 mCi) experience increased toxicity [34]. "
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    ABSTRACT: Background. The most appropriate therapy for papillary microcarcinoma (PMC) is controversial. Methods. We reviewed the therapy and outcome of 407 patients with PMC. Results. Three hundred-eighty patients underwent total thyroidectomy, and 349 patients received I-131 therapy. The median followup was 5.3 years. Forty patients developed recurrent disease. On univariate analysis, development of disease recurrence was correlated with histological tumor size > 0.8 cm (P = 0.0104), age < 45 years (P = 0.043), and no I-131 therapy (P < 0.0001). On multivariate analysis, histological tumor size > 0.8 cm, positive lymph nodes, and no I-131 therapy were significant. The 5-year RFS for patients treated with I-131 was 95.0% versus 78.6% (P < 0.0001) for patients not treated with I-131. Patients with lymph node metastasis who did not receive I-131 had a 5-year RFS of 42.9% versus 93.2% (P < 0.0001) for patients who received I-131. Conclusions. Recommend I-131 remnant ablation for patients with PMC, particularly patients with lymph node metastasis.
    03/2012; 2012:816386. DOI:10.5402/2012/816386
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    • "Such risk was particularly higher for the development of leukemia and linearly associated with the accumulated radioiodine dose. However, previous exposure to 131 I therapy was not related to increased risk for neoplasias in the breast, central nervous system, colon, rectum, kidneys, or stomach of patients with DTC as compared to the general population [13]. The differences in the findings from different studies may be related to a number of factors, among which are the particular characteristics of the studied populations. "
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    ABSTRACT: Objectives. To compare the frequency of another primary malignancy in patients with differentiated thyroid carcinoma (DTC) who received radioiodine therapy or not ((131)I). Material and Methods. 168 cases of DTC patients were retrospectively evaluated as to the frequency of another neoplasia by comparing patients with and without it, taking into account clinical, laboratory, and therapeutic parameters. Results. Another primary malignancy occurred in 8.9% of patients. Of these, 53.3% showed the malignancy before (131)I and 46.7% after it. By comparing both groups, the age at the moment of diagnosis of another neoplasia was 46.1 ± 20.2 years for the group before (131)I therapy and of 69.4 ± 11.4 years for the group after it (P = 0.02). Of the 148 patients treated with (131)I, 4.7% developed another malignancy. The latter were older (61 ± 17 years) than those who did not show another cancer type (44.1 ± 14.2 years) (P < 0.05). Conclusion. The frequency of another neoplasia found after (131)I was similar to that found before (131)I.
    08/2011; 2011:708343. DOI:10.5402/2011/708343
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    ABSTRACT: Radioiodine is a safe and well-established therapeutic modality for the ablation of thyroid remnants and the treatment of locoregional and distant metastases from differentiated thyroid carcinoma. However, a careful hazard assessment is mandatory in order to establish the risk–benefit ratio, especially in low-risk patients. Induction of second primary malignancies is one of the most serious possible untoward effects of radioiodine treatment. The limited incidence both of this effect and of thyroid cancer and the paucity of available dosimetric data make it difficult to perform high-quality studies that could provide evidence-based indications. A number of bias and confounding factors can blur data and must be considered, evaluating studies, addressing this topic. Data from the main surveys confirm that radioiodine can induce second primary tumors, with a probability comparable to that of external radiotherapy and lower than that of chemotherapy. Even though radioiodine treatment of thyroid cancer carries a low relative risk, the process of therapy justification must be carefully conducted and every measure that can reduce patient exposure must be taken, especially in children, adolescents and young adults.
    06/2013; 1(3). DOI:10.1007/s40336-013-0022-2
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