Thyroid Cancer Therapy
May Up Breast Cancer Risk
Excerpt By Suzanne Rostler

NEW YORK (Reuters Health) - Women who undergo treatment for thyroid cancer may be at increased risk of developing breast cancer up to 20 years later, according to US researchers.

Their national study found that, overall, women with thyroid cancer had an 18% higher-than-average risk of developing breast cancer. Premenopausal white women were 42% more likely to develop breast cancer, the researchers report in the July 15th issue of the journal Cancer.

``Women with a history of thyroid carcinoma have a greater than expected risk of developing breast carcinoma. This risk is most pronounced in premenopausal white women,'' write Dr. Amy Y. Chen and colleagues from University of Texas M.D. Anderson Cancer Center in Houston.

However, women with breast cancer were not found to have a higher risk of developing thyroid cancer, and black women with thyroid cancer were not found to have a higher risk of breast cancer, the investigators note.

While the findings support earlier research linking the two cancers, it is not clear why thyroid cancer might increase the risk of malignant breast tumors. One possibility is that radioactive iodine (RAI) treatment for thyroid tumors may contribute to the development of breast cancer.

``The uptake of the radioactive iodine, although low, by the breast may influence the susceptibility of the premenopausal breast tissue to the development of cancer,'' the study authors explain.

In an interview with Reuters Health, Dr. Rena Vassilopoulou-Sellin, the study's senior author, stressed that RAI remains an important and effective therapy for thyroid cancer.

``We are not suggesting that it be omitted or replaced--rather, that the possible late effect described in the paper be taken into consideration when deciding how to use RAI in the patient's care plan,'' she said.

The findings are based on data from nearly 300,000 cases of breast cancer and more than 23,000 cases of thyroid cancer reported to the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database from 1973 to 1994. Of those cases, 612 women had diagnoses of both thyroid and breast cancer, and the researchers included 365 of these women in the study.

SOURCE: Cancer 2001;92:225-231.

Reference Source 89

For more information on how to prevent other diseases, use
PreventDisease.com's "Quick Prevention Resources".