Higher Chance of Thyroid Cancer After Hysterectomy

By Alison McCook

NEW YORK (Reuters Health) - A woman's chance of developing thyroid cancer appears to increase immediately after she undergoes surgery to remove her uterus, a procedure called hysterectomy, according to researchers from Finland.   The authors note that the risk of thyroid cancer likely increases as a result of the conditions that cause a woman to undergo hysterectomy, and not from the procedure itself. Dr. Riitta Luoto and colleagues discovered that women who had a hysterectomy were twice as likely to be diagnosed with thyroid cancer within 6 months to 1 1/2 years after the operation, relative to women in the general population. The overall risk of thyroid cancer among women who underwent hysterectomy--either with or without the removal of their ovaries as well--was almost 40% higher than average, but these risks dropped significantly 1 1/2 years after the surgery. In an interview with Reuters Health, Luoto explained that women often undergo hysterectomies as a result of benign tumors called uterine fibroids, or due to bleeding disorders, often marked by heavy bleeding during menstruation. And it is likely these conditions which lead to the increased risk of thyroid cancer, Luoto said. "Hysterectomy itself does not cause increased risk of thyroid cancer," the University of Tampere researcher said. "The operation itself does not increase the risk, but stands as a marker for an increased risk," Luoto added. "Thyroid cancer and bleeding disorders...may share a common background." The precise reason why menstrual problems might be linked to thyroid cancer remains unknown, Luoto noted. The researchers obtained their findings from a review of the records of almost 18,000 women who underwent hysterectomies between 1986 and 1995 who were tracked to see if any developed thyroid cancer. Thyroid cancer occurs three to four times as often in women than in men, the authors note in the January issue of the American Journal of Obstetrics and Gynecology (news - web sites). The cancer is also diagnosed more frequently in women after they go through menopause than while they are menstruating; however, whether there are hormonal risk factors for thyroid cancer remains unclear, they write. More people are living longer now after thyroid cancer diagnoses in comparison to previous decades, Luoto and colleagues note. As of 1994, they write, 88% of people diagnosed with the disease were still alive five years later. SOURCE: American Journal of Obstetrics and Gynecology 2003;188:45-48.