What if detecting a cancer early—even before signs develop—were actually bad for your health?
That appears to be the case for thyroid cancer.
Although it’s one of the fastest-rising forms of cancer in the US, much of that is due to more screening—not more cancer. More disturbing is the growing evidence that, on balance, treating these early cases does more harm than good.
Background: Each of the past 10 years, nearly 5% more cases of thyroid cancer have been diagnosed in the US than in the year before. Unlike many cancers, thyroid cancer is easily diagnosed early—all it takes is a simple, inexpensive ultrasound of the neck, followed by a biopsy. But does finding it early save lives? Is it good medical practice for doctors to screen people with no symptoms? That was the main question posed to the US Preventive Services Task Force, a panel of independent experts who make recommendations that often become clinical standards for the medical community.
Study: The panel conducted a systematic review, looking at evidence accumulated over the years on the benefits and harms of screening for thyroid cancer. They reviewed 67 studies that involved nearly 400,000 people.
Results: The researchers found…
- No evidence that screening for thyroid cancer decreases mortality from thyroid cancer—or improves patient health outcomes. Although the rate of diagnosis has increased dramatically over the past decade or so, the rate of death from thyroid cancer hasn’t changed at all.
- One reason: It’s common for screening to identify harmless nodules containing cancer that would never have caused symptoms during that person’s lifetime.
- There is evidence that people are harmed from the treatment for the disease. Nearly everyone with papillary cancer (the most common form of thyroid cancer) has an operation to remove the thyroid. Not only are these people dependent on thyroid hormone pills for the rest of their lives, but the operation itself can cause permanent damage to the parathyroid (a gland that regulates calcium in the body) as well as to nerves around the voice box—neither of which are uncommon events.
For these reasons, the task force recommended that people who don’t have symptoms should not be routinely screened for thyroid cancer.
Bottom line: Screening people for thyroid cancer who have no symptoms does more harm than good—these tumors grow so slowly that for most people, they’re not likely to ever cause harm. But that doesn’t mean you should ignore symptoms. If you have chronic hoarseness, throat pain, difficulty swallowing or other throat symptoms…or lumps or swelling in your neck…by all means see your doctor for a neck examination, advises the task force. If it turns out to be thyroid cancer that’s causing your symptoms, treatment—which has a very high success rate—may well be the best course.
To learn more, see Bottom Line’s article “Thyroid Cancer: An Epidemic of Disease…Or Overdiagnosis?“