According to the National Cancer Institute, there are currently about 16 million cancer survivors in the United States. And new findings published in the journal Cancer suggest that some of these survivors are more likely to suffer from fatigue, even decades after treatment, reports HealthDay.

Investigators analyzed data concerning more than 300 cancer survivors (average age 74) and 1,330 individuals who hadn’t had the disease (average 69) from a long-term study on normal aging. After completing regular treadmill tests and 400-meter walks, participants rated their level of fatigue.

Cancer survivors with a history of treatment tire more easily on treadmill tests and take longer to complete the walking tests than those without cancer. (Overall, survivors walked 14 seconds slower.) Findings also showed that cancer treatment was associated with an increased risk of tiredness and being over the age of 65 was linked with a 5.7 greater risk for this decline in endurance.

“The main goal of cancer treatment has been survival, but studies like this suggest that we need also to examine the longer-term effects on health and quality of life,” said Jennifer Schrack, PhD, the study’s senior author and an assistant professor at the Johns Hopkins School of Public Health.

Once scientists are able to determine those long-term effects, Schrack believes it will help both providers and patients determine how best to treat various types of cancer.

Click here to learn how cancer treatments cause long-term problems linked to aging.