Jotanyc

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I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome!  — Kralizec! (talk) 11:16, 29 March 2010 (UTC)

Dose vs. danger

After some research, I was unable to verify the accuracy of this statement: "For this reason, high doses of the isotope are sometimes paradoxically less dangerous than low doses, since they tend to kill thyroid tissues which would otherwise become cancerous as a result of the radiation.[citation needed]." In fact, most reputable sources suggest that the lower the dose, the less dangerous it is to human health. I think that paragraph ought to be deleted. Jotanyc (talk) 21:21, 30 March 2011 (UTC)

The relative absense of thryoid cancer after therapeutic I-131 to treat Graves' disease makes it rather self-evident that if you kill all thyroid tissue with I-131, there's no thyroid tissue left to get cancer IN. How can you argue otherwise?

[1] And here is your better cite discussing I-131 treatment of Graves' disease, especially in children, which I will add: [2]:

The increased risk of thyroid cancer after thyroid irradiation in childhood has been recognized for nearly 50 yr (119).

Thus, a major concern of iodine-131 therapy relates to the risks of thyroid and nonthyroid cancers. Not surprisingly, this issue has been the focus of several long term follow-up studies involving more than 60,000 patients (56, 120–123). Studies of the effects of external radiation, diagnostic iodine- 131 use, and environmental radioiodine and g-ray exposure have also provided important insights regarding the risks of radiation exposure and thyroid carcinomas (26, 28, 124–128). These studies show that the risk of thyroid cancer is increased with exposure to low or moderate levels of external radiation. In contrast, thyroid cancer risks are much lower after high level irradiation that results in thyroid cell death or

reduced capacity of cells to divide (128, 129).

[...]

The large scale epidemiological surveys of the CTSG involving 36,050 patients in the United States (56) and the Swedish cohort studies (16, 121, 141) have provided considerable information about the relative cancer risks after iodine-131 therapy. After treatment of Graves’ disease in adults with iodine-131, which exposes the thyroid gland to high levels of radiation, rates of thyroid cancer and thyroid cancer mortality were not increased (56, 121, 141, 160).

Follow-up data involving children in the CTSG showed that thyroid adenomas developed in 30% of the patients treated in one center with low doses of iodine-131 (50 mCi/g) estimated to result in thyroid exposure of 2500 cGy (56, 88). Yet, in the other centers where children were treated with higher doses of iodine-131 (100–200 mCi/g), the incidence of thyroid neoplasms was not increased (56).

SBHarris 00:59, 31 March 2011 (UTC)

Thanks for the clarification. I guess I'm thrown by the "sometimes" -- i.e. when are high doses, in fact, more dangerous than low doses? This may seem elementary, but to the lay reader this is actually a bit confusing. (Jotanyc (talk) 15:46, 31 March 2011 (UTC))