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Article: Saara Metso, Pia Jaatinen, Heini Huhtala, Anssi Auvinen, Heikki Oksala, and Jorma Salmi Increased cardiovascular and cancer mortality after radioiodine treatment for hyperthyroidism J Clin Endocrinol Metab 2007; 0: jc.2006-2321v1 [Abstract]

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Response to: Increased mortality after radioiodine treatment for hyperthyroidism: who is the culprit

Saara Metso, Pia Jaatinen and Jorma Salmi   (13 July 2007)

Increased Mortality after RadioIodine Treatment for Hyperthyroidism: Who is the Culprit?

Muthukrishnan Jayaraman, A Verma, Harikumar KVS, KD Modi   (25 June 2007)

Response to: Increased mortality after radioiodine treatment for hyperthyroidism: who is the culprit 13 July 2007
Saara Metso, M.D. Department of Internal Medicine, Tampere University Hospital, FIN-33520 Tampere, Finland, Pia Jaatinen and Jorma Salmi Send letter to journal: Re: Response to: Increased mortality after radioiodine treatment for hyperthyroidism: who is the culprit saara.metso{at}pshp.fi Saara Metso, et al.	We thank Dr. Jayaraman and colleagues for their interest in our study and for their remarks. We would like to make some additional comments to clarify our conclusions. It is impossible to distinguish with certainty between the effects of radioactive iodine (RAI) treatment and those of hyperthyroidism, unless an untreated patient group is used as a reference, because both patient and disease characteristics affect the choice of treatment. However, a study with an untreated hyperthyroid control group would be impossible to conduct for ethical reasons. In presenting our study, we concluded that hyperthyroidism per se probably accounts for the increased cardiovascular mortality, since the cardiovascular mortality increased immediately after RAI treatment and was not explained by prevalent cardiovascular diseases (1). Three facts justify this statement. First, the cancer risk increased with the cumulative dose of RAI. Second, there was a latent period following the RAI treatment before the cancer incidence started to increase among the patients, suggesting that the difference between the RAI-treated hyperthyroid patients and the control group was caused by RAI treatment and was not due to baseline differences. Third, the increased cancer incidence was seen in organs known to concentrate iodine or to be sensitive to radiation- induced cancer, namely stomach, breasts, and kidneys (2). Our results do not imply any major need to change the present strategies in the treatment of hyperthyroidism. RAI remains the primary treatment option for most patients with hyperthyroidism. However, physicians treating hyperthyroidism must be aware of the long-term effects of hyperthyroidism and RAI treatment and take them into account in the life-long follow-up recommended for every patient treated with RAI for hyperthyroidism (3). References 1. Metso S, Jaatinen P, Huhtala H, Auvinen A, Oksala H, Salmi J 2007 Increased cardiovascular and cancer mortality after radioiodine treatment for hyperthyroidism. J Clin Endocrinol Metab 92:2190-2196 2. Metso S, Auvinen A, Huhtala H, Salmi J, Oksala H, Jaatinen P 2007 Increased cancer incidence following radioiodine treatment for hyperthyroidism. Cancer 109:1972-1979 3. Patel NN, Abraham P, Buscombe J, Vanderpump MP 2006 The cost effectiveness of treatment modalities for thyrotoxicosis in a U.K. center. Thyroid 16:593-598
Increased Mortality after RadioIodine Treatment for Hyperthyroidism: Who is the Culprit? 25 June 2007
Muthukrishnan Jayaraman, Trainee Endocrinology Dept of Endocrinology , Medwin Hospitals, Hyderabad-500001, India, A Verma, Harikumar KVS, KD Modi Send letter to journal: Re: Increased Mortality after RadioIodine Treatment for Hyperthyroidism: Who is the Culprit? jmuthukrishnan{at}hotmail.com Muthukrishnan Jayaraman, et al.	I believe that the title of the article by Metso et al. (1) seems misleading--suggesting that the greater mortality in treated hyperthyroid patients was due to radioiodine therapy. Because the study was designed to compare mortality in patients with hyperthyroidism treated with radioiodine versus healthy age- and gender-matched controls, either hyperthyroidism itself or radioiodine could have been culprit behind the observed increase in mortality. Indeed, the sustained higher mortality risk in the study population up to 25 years of follow up, as suggested by the Kaplan Meier analysis, actually strengthens the alternate hypothesis that hyperthyroidism per se, rather than radioiodine therapy, may have been a greater contributor to the increased mortality observed. Radioiodine has increasingly been recognized as a safe and effective modality of treatment for hyperthyroidism in all groups of patients, including children and younger adults (2). This article with its alarmist title, limited design, and indefinite conclusion may send a wrong message to the public, adversely affecting clinical practice. References 1. Metso S, Jaatinen P, Huhtala H, Auvinen A, Oksala H, Salmi, J 2007 Increased Cardiovascular and Cancer Mortality after Radioiodine Treatment for Hyperthyroidism. J Clin Endocrinol Metab 92:2190-2196 2. Rivkees SA, Sklar C, Freemark M. 1998. The Management of Graves’ Disease in Children, with Special Emphasis on Radioiodine Treatment. J Clin Endocrinol Metab 83:3767-3776