Thyroid cancer has been increasingly diagnosed over the last two decades because of advances in imaging, but the disease rarely poses a threat. Papillary thyroid cancer, the most common type, usually grows very slowly, so surgically removing the tumors could potentially do more harm than good.
Memorial Sloan Kettering offers patients with small, low-risk papillary thyroid tumors the option of active surveillance. In this method, doctors closely monitor the cancer rather than treating it with immediate surgery. MSK’s active surveillance program includes more than 300 patients, the largest group in the United States. Other leading cancer centers are now beginning to implement the same practice.
However, many doctors have been reluctant to adopt this approach. A study in Japan published in 2015 provided strong evidence that active surveillance is effective, but doctors in the United States have been wary of leaving any thyroid cancer untreated.
Now a study led by MSK doctors has shown virtually identical results in Americans with papillary thyroid tumors. The findings are published in the journal JAMA Otolaryngology — Head & Neck Surgery. The report validates active surveillance in the United States, providing conclusive evidence that could sway more doctors to offer the approach to their patients.
“This confirms the effectiveness of active surveillance beyond Japan. We hope it will start to change the practice of many doctors who have been on the fence,” says MSK endocrinologist Michael Tuttle, who led the study along with MSK surgical oncologist Luc Morris. “Doctors should start offering active surveillance as an option to patients and let them decide what’s right for them, even if it means a referral to another doctor.”
Slow and Steady Tumor Growth
Under MSK’s active surveillance program, tumor size is assessed by ultrasound every six months for two years, and then annually after that. This enables doctors to establish a rate of growth. The new study, which looked at 291 people who had undergone active surveillance with a median follow-up of 25 months, confirms that this growth is stable and predictable.
“The rate of growth may vary from patient to patient, but it’s always at a steady pace,” Dr. Tuttle explains. “I tell patients it’s like being on cruise control — some [tumors grow] at 10 miles per hour, some 15, and some 30. But whatever pace they’re growing, that’s the pace they stay on.”
Traditionally, if a tumor’s diameter increased by three millimeters or more — the smallest difference reliably measured by ultrasound — over any period, it was surgically removed. In the JAMA study, less than 4% had grown by that amount. Even in this small subset, some people chose to continue being observed rather than have surgery.
“We perform close to 1,000 thyroid surgeries a year here at MSK,” Dr. Morris says. “These are safe and effective operations, and cure rates for thyroid cancer are very high. But in many patients whose thyroid cancers are not destined to cause any problems for them, we can keep them just as healthy without needing to do any surgery at all.”
Although surgery for thyroid tumors is effective, it does carry minor risks of damage to the nerve that controls the vocal cords or the glands that regulate calcium in the bloodstream. In addition, people whose entire thyroid is removed have to take hormone supplements for the rest of their lives.
A Better Way to Measure
The JAMA study also showed that tumor growth could be detected more precisely by measuring for a change in three-dimensional volume rather than by looking only at the largest diameter of the tumor. This suggests that using 3-D measurement could someday become standard practice for assessing thyroid cancers because it will guide how often ultrasounds need to be done.
“Using tumor volume to measure during the first year could give us earlier answers about how fast it’s growing,” Dr. Tuttle says. “If it’s slow, you might not need an ultrasound every six months but rather every year. And then they could be spaced out even more after that.”
Dr. Tuttle emphasizes the importance of skilled ultrasound technicians and radiologists to interpret ultrasounds in order to obtain accurate tumor measurements. He says many doctors outside of cancer centers tell him they have not implemented active surveillance because they don’t feel comfortable relying on the imaging specialists that are available to them.
“If your medical practice doesn’t have access to experts that you fully trust, you still need to let patients know the option exists so they can seek that expertise elsewhere if they want,” Dr. Tuttle says.
Validation and Vindication
“I explain to some of our thyroid cancer patients that they don’t need surgery right now, and may not ever need it,” Dr. Morris says. “We talk about how we’re going to keep them under close surveillance and how we can do the surgery any time in the future if they change their mind or if their tumor keeps growing. Patients love having this option. Hearing the word ‘cancer’ is one of the scariest moments in a person’s life. Learning that your tumor may not require treatment is an incredible relief.”
Dr. Tuttle, who played a pioneering role in advocating for thyroid cancer active surveillance in the United States, is gratified to see the medical community accept a more conservative approach. He says that not long ago, the suggestion that papillary thyroid tumors could be left untreated was met with fierce resistance from many doctors — with some calling it unethical. But in 2015, the American Thyroid Association released guidelines, which Dr. Tuttle helped craft, saying that monitoring these tumors was a reasonable option.
The important message for patients, he explains, is that they should know that most thyroid cancers can be safely addressed, whether they opt for observation or surgery. Both approaches have very high success rates.
“It’s always up to the individual person and their situation,” Dr. Tuttle says. “I tell my own patients, ‘We’re going to choose between two right answers. One right answer is surgery. One right answer is watching. Let’s spend the next 30 minutes trying to figure out the right answer for you.’”
Hear Dr. Tuttle discuss this study and active surveillance in an interview with JAMA Otolaryngology–Head & Neck Surgery.