In the last 40 years thyroid cancer rates have tripled, yet mortality has stayed the same. Has there been an unusually aggressive rush to judgment in diagnosing thyroid cancer?
Since 1975, thyroid cancer incidence has tripled, while the mortality rate has stayed virtually the same. In “Current Th yroid Cancer Trends in the United States,” published in JAMA Otolaryngology — Head & Neck Surgery, researchers led by Louise Davies, MD, MS, of the Department of Veterans Aff airs Medical Center, White River Junction, Vt., and the Geisel School of Medicine, Dartmouth College, Hanover, N.H., found that this thyroid cancer “epidemic,” was attributable to overdiagnosis, particularly in women.
“The problem of increasing incidence of thyroid cancer has accelerated since we first published on the topic in 2006. Small tumors continue to make up the bulk of new thyroid cancer diagnoses, with no change in the number of people dying from thyroid cancer. Identification of small tumors without changes in the number of people dying strongly suggests we are detecting subclinical disease — cancers not destined to be a threat to that person’s life,” says Davies. This finding begs the question, are clinicians looking too hard for thyroid cancer?
Risks versus Benefits
“I think the answer is yes,” says Endocrine Society expert R. Michael Tuttle, MD, of the Memorial Sloan Kettering Cancer Center and the Joan and Sanford I. Weill Medical College, Cornell University, both in New York City. “If you look hard enough, you can find thyroid cancer, but if you are finding something that is not life-threatening and is not likely to hurt somebody, then you have to question — what is the benefit?” Th ere are negative consequences of both overtreatment and of overdiagnosis. “The downside is that patients may end up with a surgery they don’t need, and another downside is that they are now labeled as cancer patients,” Tuttle adds.
Surgery — typically total thyroidectomy — carries a 1% – 2% chance of damaging the patient’s voice and a 1% – 2% chance of causing permanent hypoparathyroidism and requiring lifelong medication. “One or two percent seems very low unless it happens to be you, in which case it’s 100%,” Tuttle says. Th at trade-off seems particularly high for a disease that probably will not ever harm the patient. Notably, before detection methods improved in the 1990s, autopsy commonly uncovered thyroid nodules in patients that died of other causes and were never aware of the neck tumors.
As for being labeled as cancer patients, Tuttle says they begin to behave and to think diff erently, which can precipitate a diff erent set of negative consequences. “My patients tell me that before they got their thyroid cancer diagnosis they described their lives as ‘before college or after college’ or ‘before I got married or after I got married.’ When they get that diagnosis, their story changes to ‘before thyroid cancer and after thyroid cancer.’ It’s a pivotal point in their lives,” he explains.
Patients begin to defi ne themselves in terms of having cancer, which becomes an emotional burden. Even when they are told not to worry because the cancer is small and probably will not progress, all they hear is, “I have cancer.” Some spend the rest of their lives wondering if they will fall into that 1% – 2% that dies of thyroid cancer or experiences recurrence. “Th is drive to fi nd every little small thyroid cancer and get it treated is certainly part and parcel of our medical community, and I’m not certain that’s a good thing,” Tuttle laments. “When you’re trying to fi nd thyroid cancer, you have to balance not only the benefi t but also these unexpected consequences.”
To Treat or Not To Treat
. . . and, If So, When?
Th e question then becomes, what would happen if papillary microcarcinoma (PMC), tumors 1 cm or less, went untreated? “Probably nothing,” says Tuttle. Because the overall survival rate is 99%, size is not a factor here, according to research. “Th e hard part is that the vast majority of them never do anything, but there are a small number of them that grow and metastasize. It’s that small number that grow and metastasize that has everybody worried,” Tuttle says. Nevertheless, detecting and treating a 1-mm tumor does not improve on the survival rate of detecting and treating a 4-cm tumor.
In the face of these data, the decision to pursue more aggressive therapies for thyroid cancer should be made after due consideration and probably a period of watchful waiting. “By and large, if we fi nd a small thyroid nodule, we should resist the urge to stick the needle into it,” Tuttle says. He recommends telling the patient it might or might not be thyroid cancer and an ultrasound will be repeated in a year. Th e vast majority will not have changed or grown, and the observation phase continues. If it has begun to grow, or if it has metastasized to a lymph node, “that marks one that was going to behave a little more aggressively, and you appropriately treat it at that time,” Tuttle says. “Th e key point is that this is not melanoma; this is not pancreatic cancer — you’ve got time here.”
The efficacy of this so-called “salvage therapy” — that is, waiting until something changes to treat — for thyroid cancer was demonstrated recently in “An observational trial for papillary thyroid microcarcinoma in Japanese patients,” published in World Journal of Surgery. Researchers led by Yasuhiro Ito, MD, PhD, of the Kuma Hospital in Kobe, Japan, studied PMC in 1,395 patients and found that those tumors that did grow or metastasize in the cohort of 309 observation patients who did not undergo immediate surgery were treated very well with surgery at a delayed date after follow-up of five or 10 years.
Risk-Adapted Therapy
Knowing that thyroid cancer is still very treatable even if it has progressed is enough for many patients to be comfortable with the wait-and-see approach; however, some patients prefer immediate biopsy. “It’s important to have the discussion up front,” Tuttle says. “I’m not saying it’s wrong to stick a needle into something small, but the patient needs to understand all of the ramifications, whereas some doctors just assume that the earlier they treat, the better. The patient needs to understand that treatment is not just a pure benefit.” Davies agrees. “Women have been affected by the problem more than men, and should be advised of both the potential harms, as well as benefits, of working up and aggressively treating incidentally detected small, asymptomatic thyroid findings,” she says.
The decision-making process between surgery and observation should be shared, but with PMC, the choice is most often between two right answers. As the expert, the clinician should guide the process, but ultimately support the patient in either approach, as long as the patient truly understands the risks and benefits of both.
However, as the idea spreads that thyroid cancer might be generally overtreated, endocrinologists are beginning to see patients with serious clinical risks rejecting surgery or who look for miracle cures in herbs and other unconventional treatments. “Thus far nobody’s been successful, and they eventually come back for surgery,” Tuttle says. “We’re not saying that thyroid cancer never needs to be treated; go stick your head in the sand. We’re saying that low-risk thyroid cancers that are a large proportion of what we’re dealing with shouldn’t be overtreated yet not to ignore real thyroid cancer and the aggressive stuff that needs to be treated in an appropriate and aggressive fashion.”
This “risk-adapted therapy” allows the clinician to slow down and be cautious with lowrisk patients, but to get high-risk patients appropriately diagnosed and treated.
Another aspect of thyroid cancer that demands a more balanced view is with access to care. While most PMC patients are being overdiagnosed, some populations with inadequate access are being undertreated, such as African American men, as reported in the March 2014 issue of Endocrine News, probably due to presentation at a more advanced stage. “Everybody wants to deal with thyroid cancer as one big group, and it’s not,” Tuttle says. “The general concept here is not to convey the idea that thyroid cancer is not cancer. There are people who die of thyroid cancer, and there are patients who need to be diagnosed sooner than they are.”
Experts agree, however, that much of the problem of overdiagnosis of thyroid cancer can be mitigated with frank patient conversations and perhaps a higher threshold to biopsy, particularly for women. Although the clinician cannot know which microtumors might become problematic, active surveillance probably will not hurt the patient’s prognosis. Moreover, less aggressive, though still experimental, therapies may be in the offing, such as very targeted laser treatment. Partial thyroidectomy or a minimalist surgical approach is sometimes another possibility. As has been demonstrated with other cancers such as breast and prostate, shared decision making in which the patient understands that he or she faces risks alongside any potential benefits, can go a long way toward reducing unnecessarily aggressive treatment.
— Horvath is a freelance writer based in Baltimore, Md. She wrote about delayed
puberty in the October 2014 issue.
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