Thyroid Cancer and Radioactive Iodine and Leukemia
January 10, 2018 / Posted by Dr. Virender Sodhi, MD (Ayurveda), ND
The Japanese atomic bomb survivors from Nagasaki and Hiroshima were exposed to ionizing radiation. The Chernobyl nuclear accident also exposed many people to radiation due to the nuclear fallout. Even nuclear factory workers are exposed to radiation. What do these people exposed to radiation have in common? They are all at a much higher risk of leukemia!
Patients with breast, gynecological, and prostate cancers, as well as patients with Hodgkin and non-Hodgkin lymphoma are often treated with radiation under a physician’s supervision. There is a lot of proof that exposure to ionizing radiation increases the risk of leukemia. Surprisingly, there is a greater risk of leukemia in patients who have had exposure to external radiation alone or with chemotherapy. Even research shows that patient exposure to radiation via diagnostic imaging devices such as CT scans, increases the risk of leukemia. Normally, the higher the total dose or volume of radiation a cancer patient has been exposed to, the greater the risk of leukemia.
Dr. Sudipto Mukherjee (an oncologist from Ohio) and his colleagues presented a study to the 2017 European Society for Medical Oncology Congress in September 2017. Dr. Mukherjee and his colleagues evaluated the risk of blood cancers such as acute myeloid leukemia and chronic myeloid leukemia in well-differentiated thyroid cancer patients treated with radioactive iodine. Radioactive iodine is a unique kind of radiation, because thyroid cancer patients must ingest it, and it becomes absorbed into the bloodstream.
The inquiry was a registry, population-based study consisting of approximately 148,000 thyroid cancer patients from 1973 to 2014, extracted from the US national cancer registry. A total of about 55% of these patients were treated with surgery alone, while about 45% had radioactive iodine following surgery. The average follow-up of these patients was approximately 4.5 years. (Mukherjee, 2017)
Among the survivors of thyroid cancer, a total of 783 patients developed leukemia after a median interval of 6.5 years from the diagnosis. The incidence of acute myeloid leukemia but not chronic myeloid leukemia in patients with thyroid cancer was linked to a truncated overall survival. In a multivariable analysis, surgery plus radioactive iodine treatment was associated with a significantly higher risk of developing acute myeloid leukemia as compared with surgery alone. The investigators discovered that in the group treated with surgery alone, there were 45 cases of acute myeloid leukemia, while the group treated with both surgery and radiation had 59 cases of acute myeloid leukemia. Other types of leukemia included: chronic myeloid leukemia, chronic lymphocytic leukemia, Hodgkin lymphoma, multiple myeloma, and non-Hodgkin lymphoma. (Molenaar, et al., 2017)
The researchers next assessed the changes in the risk of acute myeloid leukemia in both of the treatment groups by observing the change of leukemia with time and comparing the risk in these thyroid cancer groups to US population leukemia rates. In contrast to the background US population rates, the risk of leukemia was 7.1 times higher in thyroid cancer patients. The scientists noticed that after two years of post-exposure to the radioactive iodine, the risk of leukemia declined and reached a population-level rate by six years. If a thyroid cancer patient got acute myeloid leukemia, the survival rate was 8 years. If a thyroid cancer patient did not get leukemia, the survival rate was 31 years. (Mukherjee, 2017)
In recent times, there has been a significant rise in the utilization of radioactive iodine in US for treating thyroid cancer patients. In 1973, 6.1% of the patients were treated with surgery and radioactive iodine. In 2006, this number arose to 50%. Most studies report almost no advantage from radioactive iodine in low-risk and intermediate-risk tumors, a case where a five-year recurrence-free survival is greater than 97% without radioactive iodine. (Mukherjee, 2017)
It is crucial that the risks and benefits of the use of radiation therapy in cancer patients be properly weighed out beforehand. The radioactive iodine treatment in leukemia patients should be applied if absolutely necessary, because otherwise the patient is at a high risk of developing leukemia. Patients who are treated with radioactive iodine should be closely monitored, and alternative and complementary medicine can certainly come to rescue. We have patients in our clinic who have opted out to not do radioactive iodine against the wishes of their endocrinologist and are doing perfectly fine. We also have patients who got radioactive iodine, and Ayurvedic and Naturopathic medicine is also making them healthy.
A quick glance at the paper published by Dr. Mukherjee & his colleagues in the Journal of Clinical Oncology in December 2017
The primary findings of the study are the following:
- The patients with well-differentiated thyroid cancer exposed to radioactive iodine have a significantly increased risk of acute myeloid leukemia and chronic myeloid leukemia compared to general US population
- There is an increased risk for acute myeloid leukemia and chronic myeloid leukemia even in low-/intermediate-risk patients with thyroid cancer treated with radioactive iodine
- Even though the risk of acute myeloid leukemia decreases fast to baseline rates by 3 years, the risk of chronic myeloid leukemia remains elevated for up to 10 years after radioactive iodine therapy
- Patients with thyroid cancer who develop acute myeloid leukemia have shorter survival compared to those who do not have thyroid cancer
The treatment of thyroid cancer with radioactive iodine must be avoided in patients with low-risk or intermediate-risk disease, in which radioactive iodine has demonstrated almost no benefit. Always go for second opinion, and seek complementary and alternative medicine help.
- Molenaar, R. (2017). 9960 Risk of developing acute myeloid leukemia (AML) in well-differentiated thyroid cancer (WDTC) patients treated with radioactive iodine (RAI): a population-based study.
- Molenaar, R. J., Sidana, S., Radivoyevitch, T., Advani, A. S., Gerds, A. T., Carraway, H. E.,… Mukherjee, S. (2017, December 18). Risk of Hematologic Malignancies After Radioiodine Treatment of Well-Differentiated Thyroid Cancer. Journal of Clinical Oncology, 1-10.
- Mukherjee, S. (2017, December 21). Risk of AML in Thyroid Cancer Patients Treated With Radioactive Iodine. Retrieved from CancerNetwork – Home of the Oncology Journal: http://www.cancernetwork.com/