Thyroid cancer rates are skyrocketing. In 1992, 5.9 in 100,000 Americans were diagnosed with thyroid cancer, and in 2002, 9.2 in 100,000 got the diagnosis. By 2012, the most recent year for which data are available, the rate has risen to a whopping 14.9 -- two and a half times as high as it was just two decades before.
But the percentage of Americans who die of cancer in the thyroid -- a butterfly-shaped hormone gland in the neck -- hasn't budged a bit since 1992. Indeed, it's virtually the same as it was as far back as 1935.
According to a study published this week in journal Thyroid, that's because the entire increase in thyroid cancer diagnoses is the result of more effective screening methods, not more cancer. Modern diagnostic methods, such as MRIs, CT scans and ultrasound-guided biopsies, allow doctors to detect thyroid tumors -- especially small ones -- far more easily than they could before.
Yet the study noted that the small, slow-growing tumors that doctors are now able to catch aren't actually life-threatening. Indeed, they often don't cause any symptoms at all.
But isn't knowing about them better than staying in the dark?
Not necessarily. Because when screening picks up a growth, patients and doctors often move to treat it with surgery -- even if doing so wouldn't help the patient's health, and can actually hurt it.
For that reason, Mayo Clinic endocrinologist Dr. Juan Brito Campana, the lead author on the Thryoid study, said in an email, "There is absolutely no evidence that screening for thyroid cancer provides any benefit to the patients."
Unnecessary thyroidectomies always cost money -- money that could be better spent elsewhere. The researchers noted that Americans spend a total of $1.6 billion a year on thyroid cancer treatment, and that being diagnosed with thyroid cancer increases a person's risk for bankruptcy by a factor of 2.5.
But more importantly, unnecessary treatments also endanger patients' health. Anyone who has their thyroid removed must take hormones to replace those produced by the thyroid for the rest of their life. And as with any surgery -- especially one in as sensitive an area as the throat -- there are risks of complications.
Thyroid cancer is just one of a number of types of cancer that some experts say is being overdiagnosed and overtreated, to the detriment of both individual patients and the health care system as whole. Though early detection and treatment are crucial for aggressive cancers, such as those of the lungs, liver and pancreas, there's growing consensus that our approach to less aggressive cancers is flawed.
Most experts now agree that women should not be screened for ovarian cancer in the absence of symptoms of the disease. They have long cast doubt on the benefits of routine mammography and prostate cancer screening. And this summer, a major study of so-called "Stage 0" breast cancer -- formally called ductal carcinoma in situ, or DCIS -- made front-page news for its finding that treating this condition doesn't reduce breast cancer death rates at all.
Though the specifics vary from cancer to cancer, the basic principle of the argument against screening is that the harms often outweigh the benefits.
"Each individual person who is a missed diagnosis is a tragedy," explained bioethicist Dr. Robin Fiore of the University of Miami. "But every individual person who has unnecessary surgery is a tragedy as well. And in some types of cancer, there are more of the latter than the former."
Not everyone agrees, though. Dr. Therese Bevers, a professor of clinical cancer prevention at M.D. Anderson Hospital in Houston, for example, thinks that in cases where the benefits and harms of screening are close to even, the emphasis should be on reducing the harms of screening, not getting rid of it altogether.
"My concern is that we're throwing the baby out with the bathwater," she said. "Screening isn’t a bad thing as long as we aren’t treating thing that don’t need to be treated."
Many experts point to the recent experience with prostate cancer as a model for approaching this issue. In the early '90s, prostate cancer rates soared as doctors started testing many men over the age of 40 for a biomarker of the cancer, the prostate-specific antigen, or PSA, in their blood. Doctors responded by ramping up treatment, administering more radiation and removing more prostates, both of which can lead to serious side effects. But prostate cancer often grows so slowly that a large share of men with the disease often die of another condition before it becomes a problem.
For that reason, the U.S. Preventive Service Task Force recommended in 2012 that doctors stop screening most men for PSA. Screening rates have fallen modestly since then.
But doctors -- even before the governmental screening recommendation -- also shifted to a different approach to prostate cancer that is often called "active surveillance." Dr. Ashutosh Tewari, chairman of urology at Mt. Sinai Health System in New York, explained that new diagnostic tools allow doctors to monitor the progression of prostate cancer very accurately, so that they can begin treatment only when -- and if -- it starts to endanger a patient's health.
"In patients on active surveillance, we do frequent imaging and genomic analysis on biopsies of the prostate, which can tell us if the cancer is low risk or high risk," he explained. "And we've found that in between 50 and 70 percent of patients, the cancer remains indolent."
That means that a huge share of men diagnosed with prostate cancer never get treatment -- and that's a good thing.