Chronic conditions appear to be causing a poorer quality of life for childhood cancer survivors, according to a new study.

Young adults who survived cancer as children had health and wellbeing comparable to that of people nearly two decades older than them, researchers found.

"Our study is the first to use a summary measure of health-related quality of life to understand how overall well-being of adult childhood cancer survivors compares with individuals without a cancer history," said lead author Jennifer Yeh of the Harvard T.H. Chan School of Public Health in Boston.

While more than 83 percent of children diagnosed with cancer today will go on to live at least another five years, 40 percent of survivors face severe ongoing health problems, Yeh and her colleagues write in the Journal of the National Cancer Institute.

For the new study, the researchers compared the overall wellbeing of 7,105 childhood cancer survivors, ages to 18 to 49 years, with 372 of their siblings and 12,803 people in the general population.

To assess wellbeing, the researchers used participants' survey responses to assign them a score that ranged from 0 to 1, with 1 representing perfect health.

Childhood cancer survivors had a score of about 0.77, compared to a score of about 0.81 in the general population and among the siblings.

The scores for cancer survivors ages 18 to 29 were similar to scores for 40- to 49-year-olds in the general population, the researchers found.

"We found that the presence of chronic conditions was largely responsible for the difference in health-related quality of life between survivors and the general population," Yeh told Reuters Health in an email.

Past research has found that adult survivors of childhood cancer are prone to many health conditions, including weak bones, cardiovascular disease and general frailty.

In the current study, survivors who reported no chronic conditions had the same score as the general population - about 0.81.

More on this...

However, survivors' scores eroded as they reported more and more chronic conditions.

"Survivors with chronic conditions report lower health-related quality of life than individuals without a history of cancer," said Yeh. "However, survivors without chronic conditions are similar to the general population in terms of well-being. Our findings are very encouraging for the latter set of survivors."

Since the data is limited to people in early to middle adulthood, Yeh said, they can't say how survivors will fare as they get older. But their results suggest that survivors experience accelerated aging.

However, she added, it's encouraging that siblings of cancer survivors had similar health to the general population. It suggests, she said, "the cancer experience itself has minimal spillover effects on sibling long-term health."