Thyroid Cancer: How Age Affects Risk of Recurrence

with Victor J. Bernet, MD, and Jonathon O. Russell, MD, FACS

So, you've been diagnosed with differentiated thyroid cancer and have had successful treatment. That’s great news. Yet, it would be well within reason, even expected, if you find yourself wondering—what is my risk of recurrence—at any point in the future?

Photo: Kali9 @ iStock

Many factors influence the chance that you may experience a return or relapse of thyroid cancer. New data suggest that age alone appears to be an independent risk factor for predicting whether differentiated thyroid cancer, the most common kind, will reoccur,1 according to study findings published in the journal, Thyroid.

It seems that the older you are at the time of your initial diagnosis for differential thyroid cancer, the greater your risk of recurrence may be. That said, it’s important to understand that it’s not definite that the thyroid cancer will return, just an increased likelihood. Other factors, such as the stage of the cancer at diagnosis, still play a role—and the stage at diagnosis may soften the effects of increasing age,1 the researchers report.

Age at Diagnosis of Thyroid Cancer Can Predict Recurrence

This finding is not surprising, says Victor J. Bernet, MD, chair of the division of endocrinology and associate professor of medicine at Mayo Clinic College of Medicine in Jacksonville, Florida, as well as president-elect of the American Thyroid Association. He was not involved in the study but reviewed the findings for EndocrineWeb.

Age is already ''plugged in'' when researchers and physicians are trying to determine how likely a patient is to survive—what is your prognosis—after being treated for thyroid cancer, Dr. Bernet says. Therefore, ''it is not surprising that [we] could use a parameter that predicts survival or death and [age] would also predict recurrence."

This matters because the thyroid gland produces hormones that help regulate metabolism, blood pressure, heart rate and body temperature.2 About 52,000 people will learn they have thyroid cancer during this year alone, and about 2,100 will die of the disease,3 based on estimates from the American Cancer Society.

We also know that women are more likely than men to be diagnosed with differentiated thyroid cancer, and at an earlier age. Women are typically diagnosed in their 40's and 50's, while men who develop thyroid cancer are more often in their sixth and seventh decades of life. Other factors, including having overweight or obesity as well as genetics (ie, a first degree relative with thyroid cancer ) also increases the risk that you’ll face differentiated thyroid cancer.2

While the death rate has increased slightly from 2008 to 2017, the good news is that this trends to be stabilizing,2 the American Cancer Society says.

How Does Age Matter Once You've Had Thyroid Cancer?

To date, the the American Thyroid Association (ATA) guidelines focus on three categories to calculate the risk that someone who has been treated for differentiated thyroid cancer will face recurrence.4 When assessing your risk of developing thyroid cancer again, the current ATA system classifies thyroid cancer status into low, intermediate or high risk for recurrence, taking into account the stage, whether the cancer is invasive, if neck lymph nodes are involved, as well as other factors.

This team of researchers drilled down further to look at whether age at the time of a patient’s diagnosis has any direct impact on the chance that thyroid cancer will come back.  In particular, they looked at the association between age at diagnosis and rate of thyroid cancer recurrence and whether age has any influence on the accuracy of thyroid cancer reappearing based on the ATA diagnosis methods.1

To study the effect of age alone on risk of cancer recurrence, this team of researchers evaluated 1,603 patients with differentiated thyroid cancer. The patients had a median age of 49 years (half older, half younger) and a disease-free survival time of 44 months, meaning the chance of avoiding relapse of thyroid cancer was about four years for those at under age 50.1

The patients had undergone treatment at four different institutions and had undergone both thyroidectomy (a complete removal of the thyroid) and radioiodine therapy. They were followed for at least one year after treatment.  

What the researchers found was that differentiated thyroid cancer returned in 8% of these patients during the study period of January to December 2018.1 Most thyroid cancers are differentiated,2 according to the American Cancer Society, and are categorized into include one of three specific types:

  • Papillary
  • Follicular
  • Hurthle cell

In this study, the researchers divided patients into four subgroups: low-risk, intermediate-risk, high-risk younger than 56 years, and high-risk patients older than 55 years. The high-risk patients over 55, and even more so, those over 70 years at first diagnosis of thyroid cancer, were most likely to experience a recurrence of thyroid cancer.1

That pattern was true, however, only if the patient was over 55 years AND in the high-risk group; these patients were about two times more likely to have a relapse of their thyroid cancer. 1 For patients deemed at high-risk for future thyroid cancer but whose age was less than 56 years, ''showed no difference in the risk of relapse than the whole group of intermediate-risk patients," the authors said.

Based on their findings,1 the researchers suggest that the American Thyroid Association add age at diagnosis to their risk classification system to more narrowly and accurately identify patients at highest likelihood of experiencing a return of thyroid cancer. This isn’t an novel concept since age is added in another cancer staging system called the TNM (tumor, lymph node, metastasis) system.

Like all studies, this study has some limitations, say the authors. In particular, this was a ''look back'' or retrospective study that was limited to patients who had been treated with both thyroid removal and radioiodine therapy.

Therefore, the effect of age can really only be applied with assurance to someone who had undergone dual treatment like this patient population. For now, we can say that there is a relationship between age and high risk but cannot claim that age has a direct role.

Link Between Age and Repeat Thyroid Cancer is Good News

While the connection between age and return of thyroid cancer may be unsettling for anyone who is older when receiving a diagnosis of differentiated thyroid cancer, Dr. Bernet stresses that ''the vast majority [of individuals] with differentiated thyroid cancer tend to do well."

Even in patients who are at stage 3 or 4 and over 55 year, he says, many patients can expect to live for many more decades, although for some people, he acknowledges, ''there is a higher chance of [thyroid cancer] recurrence."

What does this mean for you? “If you are 55 years of age older and have one of the higher-stage cancers, be prepared for a more frequent check-up schedule. "Your doctor is going to be watching your more closely," Dr. Bernet says.

Raising another point, says Dr. Bernet, is there are no data, as yet, about whether the patients at highest risk should have different or more intensive treatments. This is a good question for further study.

Jonathon O. Russell, MD, FACS, director of endoscopic and robotic thyroid and parathyroid surgery at Johns Hopkins Medicine in Baltimore, Maryland offers further insight regarding what these findings might mean for you; he reviewed the study paper and was not involved in the study.

"We have known for decades that advanced age is one of the factors that is associated with a worse prognosis," says Dr. Russell. "This study suggests that an increased risk of recurrence may play a part in why the circumstance is often worse in older patients. However, thyroid cancer has an excellent prognosis for almost all patients, but there are a few patients who will be at increased risk of having a worse outcome."

Team Management Assures Best Thyroid Care

Dr. Russell tells EndocrineWeb: "The most important part of managing thyroid cancer is the initial treatment."  He suggests that patients ask your doctor how often they care for patients with thyroid cancer and whether a thyroid cancer specialist (oncologist) is consulted. This is important to give your some reassurance that your care is being considered by someone who is well-versed in managing all types of thyroid cancer.

"One marker of quality team-based care is having the participation of a regular and dedicated thyroid tumor conference, where specialists from multiple disciplines meet and discuss challenging cases as well as anticipated outcomes," says Dr. Russell. In this way, you can have greater confidence that your individual circumstances will be fully assessed.

The information gained from this study can be empowering and help guide the questions you may want to ask your doctor after you’ve been treated for thyroid cancer initially, Dr. Bernet tells EndocrineWeb. Three critical questions that you can raise, include:

  • What is the stage of my cancer?
  • What will the follow-up plan be? (ie, how often will you want me to return for monitoring and testing?)
  • Does my age and stage affect the frequency of how you plan to follow me? If so, how?

It's important to remember that there are a lot of individual differences to how people respond to treatment and to living with thyroid cancer, he says.  He knows of patients that he was very worried about due to their higher stage of thyroid cancer found at diagnosis, ''and then they do phenomenally well."

Neither the study authors nor Drs. Bernet and Russell have any financial conflicts regarding this research.

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