Childhood cancer survivors may have an increased risk of death from other forms of cancer, cardiac and cerebrovascular causes more than 25 years after their initial illness, UK scientists have found.

A research team at the University of Birmingham examined long-term death rates among 17,981 childhood cancer survivors, all of whom had been diagnosed before the age of 15 years between 1940 and 1991 and had lived for at least five years from their initial diagnosis.

Participants were followed up until the end of 2006, during which time there were 3,049 deaths.

Researchers found that the risk of death among childhood cancer survivors was 11 times higher than expected for the general population.

This increase in risk shrank as time went by, but was still three times higher than expected 45 years after an initial cancer diagnosis.

Although the risk of dying from cancer recurrence decreased over time, the risk of dying from second primary cancers, heart disease or stroke increased.

After 45 years, the risk of dying from a second primary cancer was 3.6 times higher for cancer survivors than for the general population.

Writing in the Journal of the American Medical Association, the study authors noted that survival from childhood cancer has improved "dramatically" in recent decades, but that survivors continue to have a heightened risk of dying for many years.

They revealed: "Beyond 45 years from diagnosis, recurrence accounted for seven per cent of the excess number of deaths observed, while second primary cancers and circulatory deaths together accounted for 77 per cent.

"Second primary cancers are a recognised late complication of childhood cancer, largely due to exposure to radiation during treatment, but specific cytotoxic [toxic to cells] drugs also have been implicated in the development of second primary cancers."

The researchers also observed: "These findings confirm the importance of very long-term outcome data and that survivors should be able to access healthcare programmes even decades after treatment.

"Finding ways to successfully intervene to reduce these potentially preventable premature deaths will be complex."

Dr Joanna Owens, science information manager at Cancer Research UK, said: "Large studies like these are essential for us to understand the long-term effects of being treated for cancer. This information will play an important part in shaping the care of children diagnosed with cancer and ensuring that they receive appropriate physical and psychological support during their treatment and beyond.

"But it's worth noting that the people in this study were diagnosed and treated between 1940 and 1991, and children diagnosed today can benefit from considerable advances in treatment. Survival rates for childhood cancer have risen rapidly since the 1960s, and it is estimated that there are at least 26,000 people alive in the UK today who have been successfully treated for childhood cancers."