The study reviewed here looked at the health histories of more than 30,000 women and men from 2 months to almost 30 years after they were treated for thyroid cancer. The researchers found that people diagnosed with thyroid cancer had a slightly higher risk of developing a second cancer within the first 10 years after their thyroid cancer treatment. After these first 10 years, risk WASN'T higher for a second cancer.
A second cancer is a new, different type of cancer, not the previously treated thyroid cancer coming back. Several different types of second cancers were seen, including breast cancer in women and prostate cancer in men.
Women between 25 to 49 years old who were previously treated for thyroid cancer had a small but definite increase in their risk for breast cancer. Because of this, the researchers recommended that younger women diagnosed with thyroid cancer start having annual mammograms within 3 years after diagnosis.
Researchers aren't sure why thyroid cancer treatment seems to increase the risk of a second cancer. Radioactive iodine is a common treatment for both an overactive thyroid gland and thyroid cancer. This treatment is considered safe and effective, but it's possible that radioactive iodine could trigger cancer in a very small number of people. Other research has shown that cancer risk, including breast cancer risk, is higher after radioactive iodine is used to treat an overactive thyroid gland. It's also possible that the genetic or other factors that contributed to a person developing thyroid cancer might increase risk for other types of cancer.
If you've been treated for any type of cancer in the past, make sure your doctor understands your unique medical history and is aware of any risks related to your past treatments. Your doctor can give you the counseling, monitoring, and screening you need to manage those increased risks. Your plan might include a more aggressive approach to breast cancer screening, including starting annual mammograms at an earlier age and other imaging techniques, such as MRI.
NEW YORK (Reuters Health) - After treatment for thyroid cancer, patients may face a slightly increased risk of developing a second primary malignancy elsewhere in the body, research suggests.
Dr. Jonathan D. Tward from University of Utah in Salt Lake City and colleagues investigated the risk of non-thyroid second primary malignancies after differentiated thyroid cancer in more than 30,000 patients diagnosed between 1973 and 2002.
During follow-up ranging from 2 to 359 months, 2158 patients developed second primary malignancies, "significantly more than that expected in the general population," the investigators report. However, the absolute excess risk was "relatively small at only about 6.5 additional cancers diagnosed per 10,000 persons per year," Tward told Reuters Health.
There was a significantly increased risk for cancers of the central nervous system, breast, prostate, kidney, Hodgkin lymphoma, leukemia, myeloma, and salivary gland, the investigators report, and a significantly decreased risk for cancers of the head and neck, lung, esophagus, and bladder.
The overall risk of second primary cancers was significantly elevated in the first 10 years after thyroid cancer diagnosis, but not for longer latency periods, the researchers note.
Patients who received radioisotope therapy -- which is commonly used to diagnose and treat certain cancers and thyroid disorders -- were at increased risk of developing non-thyroid second primary cancers, the investigators say, compared with the general population and with non-irradiated survivors of thyroid cancer.
However, Tward stressed to Reuters Health, that "radioisotope use is a safe and effective therapy whose merits far outweigh the small probability of developing a secondary cancer."
Results also showed that women in the 25-49 year age group at diagnosis of thyroid cancer had a significantly elevated risk of developing breast cancer, "although the absolute excess risk over these people's lifetimes was only an additional 4 cases of breast cancer per 10,000 persons per year," Tward explained.
"Therefore, we would advocate that any woman younger than age 40 at diagnosis perform routine breast self-examination monthly, get an annual breast physical examination by a health care provider, and begin routine, annual screening mammograms within 3 years of their thyroid cancer diagnosis," he advised.
"Screening in this manner should persist until age 40 where national consensus guidelines such as those of the American Cancer Society or the National Comprehensive Cancer Network would then take over."
"We would also recommend that all patients under age 40 at diagnosis get annual blood work to screen for hematologic (blood) abnormalities indefinitely," Tward added.
"The additional risk of prostate cancer, the other malignancy routinely screened for in the United States population, was restricted to men over the age of 50 at the time of their thyroid cancer diagnosis," he noted. "Therefore, those patients would also fall into screening standards already being implemented in the general population."
SOURCE: The Journal of Clinical Endocrinology & Metabolism, February 2008.
Breastcancer.org 7 East Lancaster Avenue, 3rd Floor Ardmore, PA 19003
Learn more about our commitment to your privacy
© 2009 Breastcancer.org - All rights reserved.
Breastcancer.org is a non-profit organization dedicated to providing information and community to those touched by this disease. Learn more about our commitment to providing complete, accurate, and private breast cancer information.
