DR.TSUBOKURA'S RADIATION LECTURE VOL.160

Author: Masaharu Tsubokura M.D., PhD.

Editor: Yudai Kaneda

319　 Attacking Bone Cancer with Radiation

March 20, 2021

The primary treatment for thyroid papillary carcinoma is surgery, but after the surgery, the patient can take a capsule containing radioactive iodine. The radioactive iodine taken in by the body gathers in the thyroid cancer and exposes the cancer cells to radiation.

This treatment takes advantage of thyroid cancer’s tendency to take up and accumulate radioactive iodine that has entered the body.

A treatment that uses a similar mechanism is radioactive radium therapy, which is applied to prostate cancer that has metastasized to the bones and is no longer responding to treatments that control male hormones.

This radium-223 has the same tendency to accumulate in bones as calcium, which is a component of bones. Therefore, when radium-223 is administered into the bloodstream, it gathers in the bones where cancer cells with an active metabolism are located. This is where the cancer cells are exposed to radiation, attacking them and suppressing the symptoms associated with bone metastasis.

On the other hand, because this treatment uses radium’s tendency to accumulate in the bones, the therapeutic drugs do not gather in the prostate or in the lymph node metastasis, and thus the treatment is not effective in those areas.

In addition to thyroid and prostate cancers, similar treatment options are available for malignant lymphoma, a type of blood cancer.

320　 Medical Treatment, Usually Iodine Restriction

March 28, 2021

In the treatment of papillary thyroid cancer, a capsule containing radioactive iodine is taken after surgery. The radioactive iodine accumulates in the thyroid cancer, which exposes it to radiation. In a similar treatment, radioactive radium, which tends to gather in the bones, is administered into the bloodstream when prostate cancer has spread to the bones and no longer responds to male hormone suppression therapy.

These treatments are called internal therapy, whereby radioactive materials are administered orally or into the bloodstream to expose cancer cells to radiation.

In contrast to this internal therapy, a treatment exists in which a small, encapsulated radioactive substance is inserted directly into the cancer cells in and around the body from outside to expose the cancer cells to radiation. This is called brachytherapy.

For example, in the treatment of early-stage prostate cancer, radioactive material is encapsulated in a titanium capsule about 1 mm x 5 mm in size, and 50 to 1,000 of these capsules are implanted in the prostate gland and the cancer cells are exposed to radiation.

The capsules remain in the prostate permanently, but the emitted radiation gradually decreases and is gone in about a year. A similar treatment may be chosen for small cancers of the tongue.The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 6 and 13 March 2021 was reproduced for MRIC Global under the author's permission.

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The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 20 and 28 March 2021 was reproduced for MRIC Global under the author's permission.