There has been a lot in the news recently about increases in the incidence of thyroid cancer, especially in women. There certainly are more cases detected now than in the past, but does that mean the cancer is actually more prevalent, or are we just much better equipped to find it? These are questions that endocrinologists are asking and most experts agree that there are no definitive answers yet.
Here’s what we know.
• The rate of mortality for men with thyroid cancer increased by 2.4 percent per year between 1922 and 2000 (the largest increase for all cancers).
• While many people develop benign thyroid lumps or nodules in the neck, only about one in twenty, less than 45,000 cases a year, are malignant.
• Even fewer have an aggressive form of the disease, which results in about 1,690 deaths per year nation-wide.
• There is a 97% survival rate after five years for those patients who do develop the aggressive form of the disease.
• Survival rates after five years in women, who are three times more likely to develop thyroid cancer than men, increased by 4.7 percent.
While we have statistical proof that the number of cases of thyroid cancer being diagnosed has increased dramatically, we also have to consider the role technology might play in helping physicians detect cancers that once would have been overlooked. In the past thirty years, ultrasound and fine-needle biopsies have helped diagnose thousands of cases that would never have been found before. Often these cancers, some of which are less than two centimeters in size, are discovered by accident during a test for another medical condition.
When small cancerous nodules are detected in the thyroid, patients usually undergo a thryoidectomy, which is the surgical removal of the entire thyroid gland, or a partial thyroidectomy. Afterward, many patients also may receive a dose of radioactive iodine to kill any remaining malignant thyroid cells. Following iodine therapy a physician can better monitor the patient with whole body scans over time to see if the cancer recurs or spreads.
Possible risk factors for thyroid cancer.
The exact cause of thyroid cancer is unknown. But, we do know that thyroid cancer occurs more often in women than men, and affects Hispanics and Asian Pacific Islanders more often than whites or blacks. There is no way for physicians to know exactly why one person develops cancer and another doesn’t, but there are some potential risk factors that may give a person a greater chance that he or she will develop the disease.
Radiation. People exposed to high levels of radiation are much more likely than others to develop thyroid cancer. One important source of radiation exposure is x-rays. Between the 1920s and the 1950s, doctors used high-dose x-rays to treat children who had enlarged tonsils, acne, and other problems affecting the head and neck. Later, scientists found that some people who had received this kind of treatment developed thyroid cancer.
Today, routine diagnostic x-rays – such as dental x-rays or chest x-rays – use very low doses of radiation. Their benefits usually outweigh their risks. However, repeated exposure could be harmful, so it’s a good idea to talk with your dentist and doctor about the need for each x-ray and to ask about the use of shields to protect other parts of the body.
Family history of medullary thyroid cancer. Medullary thyroid cancer sometimes runs in families. A change in a gene called RET can be passed from parent to child. Nearly everyone with the changed RET gene develops medullary thyroid cancer. The disease occurs alone as familial medullary thyroid cancer or with other cancers as multiple endocrine neoplasia (MEN) syndrome.
A blood test can detect the changed RET gene. If it’s found in a person with medullary thyroid cancer, the doctor may suggest that family members be tested.
Family history of goiters or colon growths. A small number of people with a family history of having goiters (swollen thyroids) with multiple thyroid nodules are at risk for developing papillary thyroid cancer. Also, a small number of people with a family history of having multiple growths on the inside of the colon or rectum (familial polyposis) are at risk for developing papillary thyroid cancer.
Personal history. People with a goiter or benign thyroid nodules have an increased risk of thyroid cancer.
Being female. In the United States, women are almost three times more likely than men to develop thyroid cancer.
Age over 45. Most people with thyroid cancer are more than 45 years old. Most people with anaplastic thyroid cancer are more than 60 years old.
Iodine. Iodine is a substance found in shellfish and iodized salt. Scientists are studying iodine as a possible risk factor for thyroid cancer. Too little iodine in the diet may increase the risk of follicular thyroid cancer. However, other studies show that too much iodine in the diet may increase the risk of papillary thyroid cancer. More studies are needed to know whether iodine is a risk factor.
Source: National Cancer Institute
Symptoms to look out for.
Early thyroid cancer often does not have symptoms, but as the cancer grows, symptoms may include:
• A lump in the front of the neck
• Hoarseness or voice changes
• Swollen lymph nodes in the neck
• Trouble swallowing or breathing
• Pain in the throat or neck that does not go away
Most often, these symptoms are not due to cancer. An infection, a benign goiter, or another health problem is usually the cause of these symptoms. Anyone with symptoms that do not go away in a couple of weeks should see a doctor to be diagnosed and treated.
Can we prevent thyroid cancer?
There is no definite way to prevent thyroid cancer. In fact, many people with thyroid cancer have no association with the possible risk factors. However, eating a healthy diet high in fruits and vegetables and low in animal fat, and maintaining a healthy weight can help to prevent many cancers.