Thyroid cancer is the fifth most common cancer among women and disproportionately affects us more than men.1 Recent studies have shown that hysterectomy—the surgical removal of the uterus and the second most common gynecological operation in the US among women of reproductive age—may be a risk factor for developing thyroid cancer.2,3,4,5
Over a decade ago, a Finnish study showed that having a hysterectomy increased the risk of thyroid cancer during the first 2 years following surgery.3 In 2016, the International Journal of Cancer published a Swedish study agreeing with these results, linking hysterectomy for the treatment of non-cancerous conditions with cancer later on in life.4
To better understand the link between hysterectomy and thyroid cancer, the scientific community has looked at other factors such as estrogen. Estrogen is thought to encourage the growth of non-cancerous and cancerous thyroid cells, prompting researchers to examine how removing the ovaries during surgery or hormone replacement therapy affects a woman’s risk of thyroid cancer.1,5
A 2016 US study examined this potential relationship and found hysterectomy to be a risk regardless of keeping or sparing the ovaries. “Our large prospective study observed that hysterectomy, regardless of oophorectomy [removal of the ovaries] status, was associated with increased risk of thyroid cancer among postmenopausal women,” writes Dr. Juhua Luo, PhD, Associate Professor of Epidemiology and Biostatistics at Indiana University Bloomington in Bloomington, Ind., and lead researcher of the study.5
Luo and her team observed 127, 566 postmenopausal women ages 50-79 in 40 clinics across the US who were part of the Women’s Health Initiative study that took place from 1993-1998. Each woman participating in the study reported if she had a hysterectomy with or without removal of the ovaries. Researchers used this information along with their medical records and confirmed any cases of thyroid cancer. The researchers followed up for an average of 14.4 years.
Results published in The Journal of Clinical Endocrinology and Metabolism showed that 36.7% of women had a hysterectomy and 55% had both their fallopian tubes and ovaries removed. After analyzing the data, researchers saw 344 cases of thyroid cancer. In comparison to women who didn’t have a hysterectomy, those who underwent surgery had a significantly higher risk of being diagnosed with thyroid cancer—regardless of whether ovaries were removed or spared. This risk was seen to increase if the surgery was done before age 50.
What’s more, hormone replacement therapy was seen to reduce the risk of thyroid cancer among women who had hysterectomy alone. This trend between hormone therapy and cancer risk wasn’t significant among women without hysterectomy or those with hysterectomy and fallopian tubes and ovaries removed. “Our data did not support the hypotheses that exogenous estrogen is a risk factor or that estrogen deprivation is a protective factor for thyroid cancer,” Luo and her team note.5
Given these results, does hysterectomy itself contribute to the risk of developing thyroid cancer?
At this time, more research is needed. It’s not clear if hysterectomy is a risk factor or if the bleeding conditions that lead to a hysterectomy have a common connection with thyroid cancer.3,5 If hysterectomy is necessary, it shouldn’t be avoided despite its possible link to cancer. However, talking to your doctor about your medical history and learning the signs and symptoms of thyroid cancer are the first steps to understanding your own personal risk.
ABOUT THE AUTHOR Alicia Armeli is a Health Freelance Writer, Editor, Registered Dietitian Nutritionist, and Certified Holistic Life Coach. She has master’s degrees in English Education and Nutrition. Through her writing, she empowers readers to live optimally by building awareness surrounding issues that impact health and wellbeing. In addition to writing, she enjoys singing, traveling abroad and volunteering in her community.
- American Thyroid Association. (2016). Clinical Thyroidology for the Public. Retrieved December 30, 2016, from http://www.thyroid.org/patient-thyroid-information/ct-for-patients/december-2016/vol-9-issue-12-p-3/
- Centers for Disease Control and Prevention. Data and Statistics: Hysterectomy. Retrieved December 30, 2016 from https://www.cdc.gov/reproductivehealth/data_stats/
- Luoto, R., Grenman, S., Salonen, S., & Pukkala, E. (2003). Increased risk of thyroid cancer among women with hysterectomies. American Journal of Obstetrics and Gynecology, 188(1): 45-48. https://www.ncbi.nlm.nih.gov/pubmed/12548194
- Altman, D., Yin, L., & Falconer, H. (2016). Long-term cancer risk after hysterectomy on benign indications: Population-based cohort study. International Journal of Cancer, 138(11): 2631-2638. doi: 10.1002/ijc.30011. https://www.ncbi.nlm.nih.gov/pubmed/26800386
- Luo, J., Hendryx, M., Manson, J., Liang, X., & Margolis, K. (2016). Hysterectomy, oophorectomy, and risk of thyroid cancer. The Journal of Clinical Endocrinology and Metabolism, 101(10): 3812-3819. https://www.ncbi.nlm.nih.gov/pubmed/27459531