What is screening for thyroid disease?
Screening aims to detect early thyroid disease, hopefully before there are any symptoms. These are important facts to realize about screening:
Screening tests are never 100 percent accurate.
Some who are screened for thyroid disease will get an abnormal screening result even though nothing is wrong with their thyroid
Others may have a normal screening test even though they have thyroid problems
These things happen with all types of screening tests.
Screening for benign (noncancerous) thyroid disease that increases or decreases the amount of thyroid hormones in the body involves a simple blood test. It is unlikely to cause you any harm, other than the inconvenience and cost of the blood test.
"About 14 in 1,000 women and about 9 in 1,000 men aged 60 years or older probably have undetected thyroid disease involving abnormal thyroid hormone levels. Through screening, these people may be identified and treated." -National Cancer Institute
Thyroid cancer screening
Doctors screen for thyroid cancer by feeling the gland, to check for a lump or nodule. If a doctor feels a nodule, it does not mean cancer is present. Most thyroid nodules are not cancer!
There are two methods of investigating a thyroid lump or nodule:
1) ultrasound, to locate and characterize the lump
Thyroid ultrasound creates pictures by bouncing sound waves off the gland. This technique is painless and quick. But it cannot, by itself, determine whether a lump is cancerous. A computer uses the ultrasound echoes to create a picture called a sonogram. From the pictures, the surgeon can see how many nodules are present, how big they are, and whether they are solid or filled with fluid.
2) biopsy, to determine if the lump may be cancerous.
Confirmation of cancer requires biopsy, usually using a fine needle (fine needle aspiration, aka FNA). Cells removed from the nodule during biopsy are sent to the laboratory where a pathologist will look at them under the microscope. If the FNA is not adequate to determine the exact nature of the cells, a surgical biopsy may be needed.
What are the pros of thyroid cancer screening?
#1 Reassurance for people who do NOT have cancer.
Most people who are screened do not have cancer. These people benefit by being reassured that they do not have cancer.
#2 Early detection for people who DO have cancer.
A few people will have cancer. These people will have their cancer found earlier than they would have otherwise, perhaps while it is very small. So, they may require less complicated treatment and have better chances of survival.
What are the cons of thyroid cancer screening?
#1 False alarms for people who do NOT have cancer.
Some people will be falsely alarmed because a nodule is found. They may need to have repeat scans, fine needle aspiration, or surgery to see whether they have cancer. Ultimately, these people learn they do not have cancer.
#2 False reassurance for some people who DO have cancer.
Screening does not find all the cancers. A few people will be falsely reassured. They do have cancer but their screening test is normal.
How many people have cancer correctly detected and how many people get false alarms?
Screening people by neck exam and ultrasound
92%-96% people will be correctly assured they do not have cancer.
4%-8% people will have false alarms and will be offered follow-up tests:
- 4%-8% people will be offered ultrasound scan
- 2%-4% people will be offered fine needle aspiration as well as ultrasound
- 1% people will be offered surgery as well as ultrasound and fine needle aspiration
People who have cancer found early may need less complex treatment and may have better chances of cure.