Thyroid Cancer: When "Watchful Waiting" Makes Sense
The most common type of thyroid cancer, called papillary thyroid cancer, traditionally has been treated with surgical removal of part or all of the thyroid gland. But, like prostate cancer, this type of cancer is rarely fatal. And so, like prostate cancer, a small tumor can be dealt with by keeping an eye on it, rather than removing the gland.
In the developed world, the number of papillary thyroid cancer cases diagnosed has jumped significantly over the past 30 years. This is due to increased use of thyroid ultrasound screenings, as well as imaging tests, like CT scans or MRIs, administered for other reasons. Most thyroid cancers, particularly small tumors, do not present with symptoms and so are often found incidentally when these tests are conducted for other health issues. Thus, more and more people are facing the issue of what to do when diagnosed with thyroid cancer.
What Is the Thyroid Gland?
Situated in the center of the neck, the thyroid gland produces a hormone that circulates through the bloodstream, affecting a variety of organ systems that modulate the body's energy use and production. An excess of thyroid hormones increases your heart rate, makes you sweat with increased sensitivity to heat, causes unintentional weight loss,, and can lead to anxiety and nervousness. Not enough thyroid hormones can cause sluggishness, weight gain, hair loss, brittle skin, and poor wound healing.
Cell mutations leading to cancer can sometimes develop in the thyroid gland. There are different types of thyroid cancer, but by far, the most prevalent is papillary thyroid cancer, accounting for 80 percent of cases.
A large study in South Korea demonstrated that despite the increased incidence of diagnosis, the death rate from papillary thyroid cancer has not changed. In other words, early diagnosis and treatment did not improve survival; if the patients had not been diagnosed early, many of them never would have needed treatment, and others whose cancers grew to a palpable size would have been treated successfully later on.
Additional research out of Japan shows that the vast majority of patients with small papillary thyroid cancers never need surgery because their tumors don't grow. Among study participants whose tumors did grow, patients who had surgery further down the line did just as well as those who had had it right away. There was no missed opportunity.
That is why there is no recommended thyroid cancer screening test, other than a physician examining your neck during routine physical exams. If any lumps or nodules are felt, an ultrasound can be performed to evaluate their characteristics and risk for cancer. Higher-risk tumors should be further evaluated and treated promptly, but recent American Thyroid Association (ATA) guidelines recommend against biopsy for low-risk thyroid nodules: those that ultrasound shows to be less than one centimeter in diameter and confined to the thyroid gland. Surgery generally can be avoided for these small, clinically insignificant cancers.
This is where an observational approach called active surveillance, also known as "watchful waiting," comes in. This alternative to surgery is restricted to papillary thyroid tumors that are less than one centimeter in diameter, and that do not have the potential to invade the surrounding structures.
Under active surveillance, patients are closely monitored, typically through ultrasound exams every six months to a year for the rest of their life. (Thyroid cancer patients who have had their thyroid removed are monitored at similar intervals.) Ultrasound carries no health risks, as it is not associated with radiation. And any papillary thyroid cancer found to have grown significantly can still be treated effectively with surgery at that time.
As with prostate cancer, the risks of immediate surgical treatment of papillary thyroid cancer may outweigh the benefits for the patient, whose cancer may never cause any problems. With the thyroid gland surgically removed, the body no longer produces thyroid hormones, so patients have to take a daily medication to keep those hormones at normal levels. With surgery also comes the risk, though rare, of permanent injury to the nerves of the vocal cord or the parathyroid glands, which control the level of calcium in the body. Thyroid surgery is most commonly done under general anesthesia, which presents its own risks. Finally, it leaves a scar on the neck.
Whether patients choose active surveillance or immediate surgical treatment, the survival rate is similarly excellent at 10 years, but anytime that surgery can be avoided safely, doing so is the clinically preferred option.
Unfortunately, many candidates for active surveillance are still being biopsied and having surgery. Receiving a diagnosis of cancer and not treating it is understandably scary for many, even when they are assured that the cancer will likely never grow or need surgery. And surgeons tend to be aggressive in recommending thyroid gland removal and subsequent monitoring.
Still, it is important for patients to make an informed treatment decision. Thyroid cancer is addressed by a team of doctors, including a primary care physician, endocrinologist, and surgeon. When appropriate, both surveillance and surgery options should be presented with all the risks and benefits described.
Watchful waiting may help many patients avoid surgery altogether, but some people may feel too anxious living with a cancer diagnosis and still decide that surgery is right for them. No matter what the patient chooses, it is vital for the entire team to support his or her decision.