Thyroid function after cancer treatment

Photo: Allie Smith/Unsplash. Design: BOOST Thyroid.

Photo: Allie Smith/Unsplash. Design: BOOST Thyroid.

How chemotherapy and radiotherapy impact thyroid function

An unfortunate side effect of cancer treatment is developing thyroid problems—this can occur from both radiotherapy and chemotherapy. While most thyroid problems happen within five years of completing cancer treatment, for some people thyroid problems might happen decades after treatment (1).

Underactive thyroid caused by radiotherapy

Radiotherapy aimed at the head and neck might affect the thyroid gland, causing it to become underactive.. Radiotherapy has a huge impact on thyroid cells, causing many to die, as well as changing the inner structure of the thyroid gland and causing chronic inflammation (2).

This effect of radiotherapy typically occurs years after treatment, , on average about 2–7 years later depending on the dose and the length of the treatment (3-5).

Half of patients who receive radiotherapy will develop an underactive thyroid (6-9).

Underactive thyroid caused by chemotherapy

Both traditional chemotherapy as well as its “smart” drugs (medications that target specific molecules almost exclusively found in cancer cells) can also cause hypothyroidism. Chemotherapy can cause an underactive thyroid in 7 in 10 patients (10-13).

Smart drugs that may cause side effects include (14 - 23):

  • Bexxar

  • Gleevec/Glivec

  • Recentin

  • Sprycel

  • Sutent

  • Tasigna

  • Targretin

Traditional chemotherapy (through medications such as Cytoxan, Neosar, Methotrexate, Adrucil, Carac, Efudex, Efudix, Navelbine, Adriamycin, Caelyx, Myocet, Blenoxane, Velban, DTIC-Dome, Prednisolone, Matulane, Natulan, Indicarb, Oncovin, Vincasar, Platinol, Etopophos, Toposar, Ellence, Xeloda, Eloxatin, Leucovorin, Nolvadex, Genox, Tamifen) can also affect thyroid function (24).

Furthermore, drugs modulating the immune system (including interleukin-2, interferon-alpha, Thalomid, and Revlimid) can also cause an underactive thyroid (25-27). If an underactive thyroid occurs when a patient is treated with this type of medication, it usually happens around 4 months after starting treatment (28).

The drug ipilimumab (Yervoy) affects thyroid indirectly, by triggering autoimmune destruction of the pituitary gland which leads to lower TSH and an underactive thyroid (28).

How to get diagnosed post-treatment

Thyroid problems can happen at any point—between a few weeks to several decades after the cancer treatment. It depends on the type of therapy, dosage, and duration of treatment, as well as individual genetic predispositions.

The most common signs and symptoms of an underactive thyroid are fatigue, weight gain, sleep problems, and headaches. However, lots of people experience less common symptoms as well.

If you suspect you might have an underactive thyroid, tell your doctor the details of your cancer treatment, as well as the intensity and the type of symptoms you are currently experiencing.

This will help your doctor with establishing your health history and with selecting an appropriate way to manage your condition.

Download BOOST Thyroid today. You can track your symptoms and quickly gauge if and how well your treatment is working.


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  2. Nishiyama K, et al. A prospective analysis of subacute thyroid dysfunction after neck irradiation, 1996

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  6. Garcia-Serra A, et al. Thyroid function should be monitored following radiotherapy to the low neck, 2005

  7. Norris AA, et al. Hypothyroidism when the thyroid is included only in the low neck field during head and neck radiotherapy, 2006

  8. Chow LM, et al. Survival and late effects in children with Hodgkin’s lymphoma treated with MOPP/ABV and low-dose, extended-field irradiation, 2006

  9. Metzger ML, et al. White race as a risk factor for hypothyroidism after treatment for pediatric Hodgkin’s lymphoma, 2006

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  11. Rutkowski P, et al. The outcome and predictive factors of sunitinib therapy in advanced gastrointestinal stromal tumors (GIST) after imatinib failure—one institution study, 2012

  12. Del Fabbro E, et al. Extreme hypothyroidism associated with sunitinib treatment for metastatic renal cancer, 2012

  13. Feldt S, et al. Incidence of thyroid hormone therapy in patients treated with sunitinib or sorafenib: A cohort study, 2012

  14. Khaleel KJ, et al. Thyroid dysfunction in chronic myeloid leukemia patients on nilotinib, 2018

  15. Faivre S, et al. Molecular basis for sunitinib efficacy and future clinical development, 2007

  16. Cella D, et al. Health-related quality of life in patients with metastatic renal cell carcinoma treated with sunitinib vs interferon-alpha in a phase III trial: Final results and geographical analysis, 2010

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  18. de Groot JWB, et al. Imatinib induces hypothyroidism in patients receiving levothyroxine, 2005

  19. Goss GD, et al. Randomized, double-blind trial of carboplatin and paclitaxel with either daily oral cediranib or placebo in advanced non-small-cell lung cancer: NCIC clinical trials group BR24 study, 2012

  20. Kim TD, et al. Thyroid dysfunction caused by second-generation tyrosine kinase inhibitors in Philadelphia chromosome-positive chronic myeloid leukemia, 2010

  21. Gopal AK, et al. High-dose [131I]tositumomab (anti-CD20) radioimmunotherapy and autologous hematopoietic stem-cell transplantation for adults > or = 60 years old with relapsed or refractory B-cell lymphoma, 2007

  22. Press OW, et al. Phase II trial of CHOP chemotherapy followed by tositumomab/iodine I-131 tositumomab for previously untreated follicular non-Hodgkin’s lymphoma: Five-year follow-up of Southwest Oncology Group Protocol S9911, 2006

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  25.  Hancock SL, et al. Thyroid disease after treatment of Hodgkin's disease, 1991 

  26. Sklar C, et al. Abnormalities of the thyroid in survivors of Hodgkin's disease: Data from the Childhood Cancer Survivor Study, 2000

  27. Braverman L. E., Cooper D. S., editors. Werner & Ingbar’s the thyroid: A fundamental and clinical text. Philadelphia, PA: Lippincott Williams & Wilkins; 2000

  28. Riksfjord HOP, et al. Thyroid dysfunction from antineoplastic agents, 2011

Vedrana Högqvist Tabor