July 13, 2010 -- Children who beat cancer face an increased risk of death from second primary cancers and cardiovascular diseases 25 years or more after their initial diagnosis and treatment, says a new study in The Journal of the American Medical Association.
With a team of colleagues, Raoul C. Reulen, PhD, of the University of Birmingham in England, studied long-term deaths among 17,981 people in Britain who had survived childhood cancer for five years or more after their initial diagnosis.
The people in the study were diagnosed with cancer before age 15 between 1940 and 1991 and were followed until the end of 2006.
Scientists say 3,049 deaths occurred during the study period and that survivors of childhood cancer had 11 times the number of deaths that would have been expected in the general population. The mortality rate was still three times higher than expected 45 years after diagnosis.
“Over recent decades, survival from childhood cancer has improved dramatically, yet mortality rates in childhood cancer survivors continue to be elevated for many years beyond five-year survival, compared with the general population,” the researchers write. “Although studies have shown that the risk of death from recurrence decreases with increasing time since five-year survival, uncertainty about the long-term risks of death from other causes remains.”
This type of long-term cause-specific mortality is important “because any excess mortality may be related to long-term complications of treatment,” the researchers write.
The absolute death risk for recurrence declined from diagnosis at age 5 to 14 to beyond 45 years from diagnosis.
Absolute death risk from second primary cancers and circulatory disease from cardiac and cerebrovascular deaths increased, however.
“Beyond 45 years from diagnosis, recurrence accounted for 7% of the excess number of deaths observed while second primary cancers and circulatory deaths together accounted for 77%,” the researchers write.
The excess deaths due to second primary cancer and circulatory disease likely are caused by late complications from initial treatments, the researchers say.
“Second primary cancers are a recognized late complication of childhood cancer, largely due to radiation during treatment, but specific” drugs that are toxic to cells also have been implicated in second primary cancer diagnoses, the researchers write.