sábado, 16 de junio de 2012

Low-Dose Radioactive Iodine Destroys Thyroid Tissue Left after Surgery - National Cancer Institute

Low-Dose Radioactive Iodine Destroys Thyroid Tissue Left after Surgery - National Cancer Institute


Low-Dose Radioactive Iodine Destroys Thyroid Tissue Left after Surgery

Adapted from the NCI Cancer Bulletin.
A low dose of radioactive iodine given after surgery for thyroid cancer destroyed (ablated) residual thyroid tissue as effectively as a higher dose, with fewer side effects and less exposure to radiation, according to two European randomized controlled trials published May 3, 2012, in the New England Journal of Medicine. Both trials also showed that either administering thyrotropin alfa or withdrawing thyroid hormones before administering radioactive iodine was effective for thyroid ablation at both radioactive iodine dose levels.
Researchers from France and the United Kingdom enrolled 752 and 438 patients with low-risk thyroid cancer, respectively, in their trials (here and here). Both studies randomly assigned patients to receive either low-dose radioactive iodine (1.1 GBq) or high-dose radioactive iodine (3.7 GBq) several months after surgery.
For radioactive iodine treatment to work, thyroid-stimulating hormone (thyrotropin) levels must be elevated. The researchers therefore randomly assigned study participants in both dose groups to either withdrawal of the replacement thyroid hormones given after surgery (to allow the body’s own thyrotropin level to rise) or administration of recombinant thyrotropin (thyrotropin alfa). Although thyrotropin alfa causes less discomfort than the withdrawal of replacement thyroid hormones, there was some concern that the drug might interfere with the effectiveness of radioactive iodine treatment.
Low-dose and high-dose radioactive iodine resulted in similar numbers of successful ablations in both trials: about 95 percent of patients in the French trial and 85 percent of patients in the U.K. trial, which enrolled patients with larger tumors than the French trial. In both trials, at both dose levels, rates of successful ablation did not differ significantly between patients receiving thyrotropin alfa or those undergoing replacement thyroid hormone withdrawal.
Ablation of residual thyroid tissue with radioactive iodine makes it easier to monitor patients with low-risk disease for local or distant recurrence, and its use has been rising in the United States. One study found that the use of ablation in younger patients with low-risk thyroid cancer rose from about 3 percent in 1973 to about 40 percent in 2007.
But whether radioactive iodine improves survival for low-risk patients remains unknown. “That benefit is much harder to prove in low-risk individuals because their survival from this disease is so good to begin with,” explained Erik Alexander, M.D., of Harvard Medical School, who co-authored an editorial accompanying the two trials. A trial testing whether radioactive iodine improves disease-free survival in low-risk patients was recently launched in the United Kingdom.
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Thyroid Cancer Seldom Shortens Lifespan, Study Finds

Only difference seen in patients in most advanced stages

By Robert Preidt
Monday, June 11, 2012
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MONDAY, June 11 (HealthDay News) -- Most people with thyroid cancer live as long as people who don't have the disease, a new study finds. Patients with advanced thyroid cancer are the exception.
German researchers analyzed data from 1,502 patients with differentiated thyroid cancer (which includes two types of thyroid cancer, follicular and papillary) had been treated with radioiodine therapy. Only patients with advanced disease (stage 4-c) had a lower chance of long-term survival than the general population.
Survival did not vary based on age or sex, or even if a patient's cancer had reached the beginning of stage 4.
The study was scheduled for Monday presentation at the Society of Nuclear Medicine annual meeting in Miami Beach, Fla.
"With these survival rates, patients with differentiated thyroid cancer in stages 1 to 4-a could even be considered healthy patients," lead investigator Dr. Alexis Vrachimis, at the department of nuclear medicine, University Hospital Muenster, said in a society news release.
The researchers said the findings highlight the excellent diagnostic and treatment methods available to patients with differentiated thyroid cancer, which is the most common form of the disease.
More than 56,000 Americans will be diagnosed with thyroid cancer and nearly 1,800 will die of the disease in 2012, according to the U.S. National Cancer Institute.
Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
SOURCE: Society of Nuclear Medicine, news release, June 7, 2012
HealthDay
More Health News on:
Thyroid Cancer

 
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Thyroid Cancer


 
 
Your thyroid is a butterfly-shaped gland in your neck, just above your collarbone. It makes hormones that help the body work normally. Anyone can get cancer of the thyroid gland. But certain factors may increase the risk. These include
  • Being between ages 25 and 65
  • Being a woman
  • Being Asian
  • Having a family member who has had thyroid disease
  • Having radiation treatments to your head or neck
You should see a doctor if you have a lump or swelling in your neck. Your doctor can order tests to see if you have cancer and, if so, which type. Treatment depends on the type and how far the cancer has spread. They include surgery, radioactive iodine, hormone treatment, radiation therapy or chemotherapy. Some patients receive a combination of treatments.
NIH: National Cancer Institute

Illustration of the thyroid showing the parathyroid glands

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