27 Avril 2012
April 27, 2012
There are concerns that radiation from the Fukushima No. 1 Nuclear Power Plant may cause thyroid gland cancer. The Mainichi answers common questions readers may have about this cancer.
Question: Why is there concern about thyroid gland cancer?
Answer: After the 1986 Chernobyl nuclear disaster, thyroid gland cancer increased among children who ate foods contaminated with radioactive iodine. The surge in thyroid gland cancer started four years after the disaster, and the progress of the cancer is slow, so in the case of the Fukushima disaster, an increase in thyroid gland cancer would not be seen yet.
At Chernobyl, thyroid gland cancer increased after radiation exposure equivalent to around 10 sieverts across one's lifetime. In the case of Fukushima, regulations on radioactive food were soon put in place, so the amount of radioactive exposure is much less, and medical professionals have projected that thyroid gland cancer cases will not increase.
Q: How have thyroid gland ultrasound tests for children under 18 in Fukushima Prefecture gone?
A: Results as of November last year, released by the Fukushima Prefectural Government, were that among 3,765 people tested, around 30 percent had tumors of two centimeters or smaller found, but no children had malignant tumors. If a tumor is nonmalignant then treatment is not necessary. It is also said that nonmalignant tumors hardly ever change into malignant tumors.
Q: What does the thyroid gland do?
A: The thyroid gland, an organ around five centimeters tall and three centimeters wide located beneath the Adam's apple, makes growth and digestion hormones using iodine as a base material. These hormones are essential to growth, and children have a high absorption rate for iodine.
Q: Can thyroid gland cancer be cured?
A: Both adults and children can be treated if thyroid gland cancer is detected. Over 90 percent is a type called papillary, and if surgery is done the rate of survival for the next five years is 92 percent. According to hospital head and thyroid gland specialist Koichi Ito, the younger the patient the better the chance of recovery.
Q: How many people get thyroid gland cancer?
A: According to research by Doctor Shinichi Suzuki of Fukushima Medical University, it is very rare among children, with patients 14 or under accounting for only 0.3 percent of cases. According to the National Cancer Center, as of 2006 the thyroid gland cancer rate was 6.2 people per 100,000. As of 2010, the death rate from it was 0.6 people per 100,000. Compared to other cancers affecting Japanese people, the death rate was low. It is said that because the progress of the cancer is slow, many people die of other ailments before noticing they have it. (Answers by Hanayo Kuno, Science & Environment News Department)