TUESDAY, Jan. 24, 2017 (HealthDay News) -- Younger survivors of thyroid cancer are at increased risk for certain types of health problems later in life, a new study suggests.

"As the number of thyroid cancer survivors grows, more people are living with other serious health conditions resulting from treatment," study lead author Brenna Blackburn said in an American Society of Clinical Oncology news release.

Blackburn is a graduate research assistant at the University of Utah in Salt Lake City.

In the new study, her team tracked data from more than 3,700 thyroid cancer survivors in Utah diagnosed between 1997 and 2012. The researchers compared those patients' long-term health to that of more than 15,500 people who did not have thyroid cancer.

The study found that thyroid cancer survivors diagnosed before age 40 were five times more likely to develop swelling around the heart, and more than twice as likely to develop heart valve disease, compared to people in the other group.

People diagnosed with thyroid cancer when young were also more than seven times more likely to develop osteoporosis, and more likely to have high blood pressure and heart rhythm disorders, Blackburn's team said.

Even people diagnosed with thyroid cancer at a later age -- after 40 -- had an increased risk for various health problems, but the effect wasn't as strong as was seen in people diagnosed at a younger age. People diagnosed when over 40 were 46 percent more likely to develop high blood pressure and more than twice as likely to develop osteoporosis than people who'd never had thyroid cancer, the study found.

The study was presented on Monday at a meeting of the American Society of Clinical Oncology in San Diego.

Blackburn stressed that, nowadays, "patients diagnosed with thyroid cancer often have an excellent prognosis and survival rate, especially those diagnosed at younger ages, with less than 3 percent of thyroid cancer deaths occurring in patients diagnosed before age 40."

However, longer-term risks to health may emerge later, she added.

"It's important to understand these long-term risks so that we can not only help manage their health, but also inform how oncologists care for these patients from the onset of diagnosis," Blackburn said.

Two experts in thyroid cancer care said that a more nuanced view of the disease and its treatment may help lower long-term health issues in the future.

"In the recent past, most patients with thyroid cancer were treated with surgical removal of the entire gland, followed by radiation given in the form of radioactive iodine," explained Dr. Daniel Kuriloff. He directs the Center for Thyroid & Parathyroid Surgery at Lenox Hill Hospital in New York City.

"Standard treatment in the past has also required thyroid hormone replacement at much higher doses than normally required for general health," he added. That can boost the risk of osteoporosis and heart disease, Kuriloff said.

But better detection means that thyroid tumors are now being spotted earlier and more frequently. Many may be so "slow-growing" they pose little threat to health," Kuriloff said.

With that in mind, "we are developing new standards of less aggressive treatment for young, 'low risk' patients under the age of 45," he said.

"This study underscores the importance of risk stratifying patients into low, intermediate and high risk disease, to help determine if any treatment is needed," Kuriloff said.

Dr. John Allendorf is vice chair of surgery at Winthrop-University Hospital in Mineola, N.Y. He said the study findings aren't surprising, since many of these long-term health risks from thyroid treatment were already well-known.

He agreed with Kuriloff that "there is likely a population of patients that can be identified whose risk of recurrence is so low that the standard practice of thyroid hormone replacement does more harm than good."

According to the study authors, thyroid cancer incidence is increasing more rapidly in the United States than any other cancer. This year, about 64,300 adults will be diagnosed with the disease. However, treatment is usually very effective, so the vast majority of patients survive their disease.

More information

The U.S. National Cancer Institute has more on thyroid cancer.