Josh Green’s novel — and recent film — The Fault In Our Stars (TFIOS) is a new classic of young adult fiction, deservedly famous, and it’s easy to see why. The story is simultaneously deeply sad and really funny, mostly due to the narrator, Hazel. She is an intensely likable 16-year-old, who charms you even while she explains, stoically, that she is dying of thyroid cancer that has spread to her lungs and is slowly making it impossible for her to breathe. If you are over 30 and not masochistic, nothing about this description probably makes you want to read the book, but read it anyway.

I say that even though I was the wrong audience. The problem was that I treat a lot of patients with thyroid tumors. This made me experience TFIOS off-kilter, in sort of the same way that some physicists watched Gravity without realizing that the title is mostly a metaphor. Unlike Gravity, though, Green’s book gets the technical details right. Essentially everything medical that happens to Hazel really does happen to a very small percentage of patients with thyroid cancer. I met families with stories very similar to hers when I was training at a specialized cancer hospital.  But, those are very rare cases. You might meet hundreds of young people with thyroid cancer before you met one with a story remotely like Hazel’s.

As literary criticism, that observation isn’t worth anything. The fact that a disease is rare doesn’t make it less important to the person who has it, and TFIOS is about individuals, just like life. But, the difference between Hazel’s plausible narrative and the typical case of thyroid cancer isn’t just a dry statistical claim — it’s a gulf, wide and deep, part of a fault that runs right through our language.

If you formed your whole impression of thyroid cancer from TFIOS you would simultaneously be right about many facts but fundamentally wrong about the nature of the disease. You would think of it as a typical cancer: relentless, deadly, life-altering, in need of the most aggressive treatment. That conception, which is reinforced by almost everything anybody writes or says about cancer, will shape the kinds of treatment you and your doctor choose, possibly pushing you both to make bad decisions. This really matters, because here is the thing about thyroid cancer: There’s at least a 10 percent chance that you have it right now.

We believe that a large, double-digit percentage of the population eventually develops cancer of the thyroid; it just progresses so slowly that you never find out about it and eventually you die of something else instead. Autopsy studies have generally shown that about 10 to 15 percent of people — who all died of other causes — have cancerous cells in their thyroid. Experts speculate that if researchers looked harder — essentially sectioned the thyroid more finely and looked at more slides of tissue — they might have found such cells in even more people.

In medical care, it’s very unusual ever to search through the thyroid in such detail, but even so enough thyroid cancer is detected in living patients to make it one of the most common cancer diagnoses in the U.S. Over 500,000 Americans are currently living with it. Systematic screening (which nobody recommends) would increase that number to the millions, possibly to over ten million. In that sense, Hazel is in company with an astonishingly large number of people.

But in other sense, she is almost alone. It is remarkably rare for thyroid cancer to progress to life-threatening complications. The large majority of patients are diagnosed at stage 1, and for them the 5-year death rate is indistinguishable from the general population. Behind these numbers is a fact that matters to the individuals involved: While there is tremendous variation in what can happen, and some cases are aggressive and deadly, the vast majority of people diagnosed with thyroid cancer never even come close to the complications Hazel experiences. No metastases to the lung, no shortness of breath or  oxygen cannulae, no visits to urgent care or the emergency room or intensive care unit, no chemotherapy.

Despite this, thyroid cancer is still called cancer. You hear the word, and a certain kind of narrative — Hazel’s — always flashes in your mind. Treatment is aggressive. About 63,000 new cases of thyroid cancer are diagnosed each year in this country and almost all are treated with surgical removal of the thyroid. Thyroidectomy is safe, for a surgery, but still has risks, most significantly a 1 percent risk of permanent vocal cord paralysis. Around the surgery are concentric rings of other costs – emotional stress, repeated visits for monitoring, lifelong need for thyroid hormone supplementation, and many more.

These treated cases might still represent a triumph of modern medicine if the result were a fall in the rates of death or complications from thyroid cancer, but in fact the death rate has stayed flat even while the rate of diagnosis and treatment has tripled since the 1970s. The epidemiology and biology suggest an explanation: Most of the cases being treated are early stage cancer that might have never progressed to endanger patients, or even cause symptoms. The net impact of this vast effort seems to be little or no benefit, balanced against the mental and physical toll of a cancer diagnosis followed by surgery and other treatments. The result is a strange near-paradox that’s not uncommon in modern medicine: We are diagnosing many people with a disease who would be better off if they never knew they had it.

How did we get here? For most of the 20th century, thyroid cancers were usually diagnosed only once there was a mass in the neck that a person could see or feel. That usually happened when a tumor was growing quickly or already very large, signs associated with bad disease. These patients were much more likely to develop serious, life-threatening complications, and there was little doubt that surgery and further aggressive treatment were right for them.

In this century, MRI, CT, and ultrasound scans are widely available and can image the thyroid in detail. It is particularly easy to do a thyroid ultrasound on the faintest suspicion of a thyroid abnormality. Some doctors even obtain thyroid ultrasounds as a screening test for all their patients, contrary to professional guidelines. Screening 100 randomly selected people with such an approach will typically diagnose several cases of thyroid cancer. But, the vast majority of these diagnoses are so-called incidental discoveries, akin to the tiny thyroid cancers discovered on autopsy. Statistics strongly suggest that most of these progress so slowly that the best course of action would be no treatment.

But that’s an inference, made with reasonable confidence based on epidemiologic data, that can’t be applied with true certainty to a given individual. These incidental discoveries are still biologically cancers, however slow growing. Few patients are comfortable allowing a known cluster of malignant cells to stay in their bodies, and most physicians don’t argue the point. There are a few small studies underway to establish the safety of monitoring patients with the smallest thyroid cancers, without resorting to surgery right away. But the overall trend is still in the other direction, towards more diagnoses and more surgeries.

This is a health policy problem without an easy solution. It is awful to contemplate diagnosing a seemingly typical case of early-stage thyroid cancer, failing to treat it aggressively, and seeing the patient be one of the very few who develop widespread metastases and die. The most substantive solution so far has been changes in professional guidelines to encourage less use of diagnostic tests so that we diagnose fewer asymptomatic cases. It’s so hard to counsel watchful waiting once the cancer diagnosis is rendered that we’ve decided it’s best to try not to look too hard at your thyroid in the first place, because we can give you better medical advice by knowing less about you.

Another promising idea is a purely linguistic fix: Just stop calling the disease cancer. The idea is to re-name many thyroid cancers “indolent lesions of epithelial origin.” (The proposal that this phrase can be turned into the acronym IDLE is probably a bridge too cute). The arcane specificity of this terminology would scare fewer people, and set the stage for a more balanced discussion of the clinical options.

There’s nothing silly about the proposal: Names are very powerful in medicine. All diagnosis is is accurate naming. Hazel had thyroid cancer. Most of us have IDLEs (fine, the acronym can stay). Presumably a simple re-naming wouldn’t radically change anything, but would gradually allow standards for diagnosis and management to evolve in a more rational, less aggressive direction. Nonetheless, it’s hard to avoid feeling that this a little glib, and that patients who go home and Google the phrase may feel more than a little deceived when they learn that a commonly used alternative name for their condition is “cancer.”

Personally, I think this is a problem where the solution is to talk about it for a long time. Patients with known or suspected thyroid cancer deserve a long conversation with their doctor, one that includes both the term “IDLE” and the word “cancer.” If you take enough time in the consultation room, people understand the nuances of the situation. In most cases, what has to be explained is that thyroid cancer is a potential threat, but one that is very different from a literary cancer diagnosis. In TFIOS, cancer has the guaranteed lethality of a gun on the mantelpiece. In life, sometimes it’s something you grow old with.

James Flory is an endocrinology fellow.