Late Effects of Thyroid Cancer Are More Prevalent in Younger Survivors

There was an increased risk of late effects such as hypertension, heart disease and osteoporosis in patients who were diagnosed with thyroid cancer before the age of 40, according to the results of a recent study.

The findings were presented by Brenna Blackburn, M.P.H., of the Huntsman Cancer Institute, at a press briefing in advance of the 2017 Cancer Survivorship Symposium to be held Jan. 27-28 in San Diego.

Thyroid cancer is the most rapidly increasing cancer in the United States, with 64,300 cases diagnosed in the US last year. It is also considered a “young disease,” in that nearly 2 out of 3 cases are diagnosed in patients under the age of 55, Blackburn noted.

“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,” she said.

However, as the number of thyroid cancer survivors grows, more people are living with other serious health conditions resulting from treatment. “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.”

For their study, researchers examined whether younger thyroid cancer survivors were at greater risk of late effects than older patients for diseases associated with aging, such as osteoporosis and cardiovascular disease. Researchers defined late effects as “conditions or diseases occurring after the cancer diagnosis, caused by the cancer treatment years later.”

Using the Utah Population Database, the researchers matched five cancer-free individuals for every thyroid cancer survivor, between the years 1992 and 2012. To identify late effects, researchers used electronic medical records, statewide ambulatory surgery and inpatient discharge data. The patients were analyzed over three time periods: one to five years after cancer diagnosis, five to 10 years after cancer diagnosis and more than 10 years after cancer diagnosis. The models were adjusted for birth year, birth state (whether in Utah or outside the state), gender, race, baseline body mass index and baseline Charlson Comorbidity Index, which assesses patients’ health status using comorbid conditions such as diabetes and congenital heart failure.

A total of 1,365 thyroid cancers diagnosed before the age of 40 were matched to a total of 6043 cancer-free control participants. The thyroid cancer survivors compared with matched cancer-free individuals had over twice the risk of hypertension in the one to five year period, and their risk remained significantly increased across all three study time periods. Thyroid cancer survivors were nearly five times as likely to develop swelling around the heart in the less than 10 years’ time period and 7.5 times as likely to develop osteoporosis overall.

For the patients diagnosed at age 40 or older, 2,341 thyroid cancer survivors were matched to 9,544 cancer-free individuals. When compared with the cancer-free group, thyroid cancer survivors had significant risk increases, but not as high as the younger population. For example, survivors had a 1.5 fold increased risk of hypertension across all three time periods, and double the risk of osteoporosis in the one to five year time period.

The increased risk of late effects for patients diagnosed younger than age 40 could be caused by more aggressive treatment for younger patients in the form of hormone therapy and radiation, Blackburn noted. Preliminary analysis suggests that younger patients are more likely to receive radiation than older patients.

Blackburn explained that we do not know enough about late effects for this relatively young disease. “Younger patients are often considered healthier, and it’s assumed they’re better equipped to handle aggressive types of therapy that have been linked to heart damage, such as radiation and hormone therapy. But we’ve seen that they’re also developing worrisome side effects later,” Blackburn said.

ASCO Expert Merry Jennifer Markham, M.D., who moderated the press cast, concurred, noting, “This study helps to underscore the need for personalized survivorship care and highlights areas to focus on in these patients, particularly cardiac risks.”

New guidelines from the American Society of Clinical Oncology address cardiac dysfunction in cancer survivors and recommend that clinicians complete a careful history and physical examination in patients who are receiving treatments that can potentially result in heart damage. The guidelines also refer patients to cardiologists for early management.