Childhood cancer survivors face an enhanced risk of death from second primary cancers, cardiac and cerebrovascular causes during their adulthood,even 25 years after their initial 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 5-year survival compared with the general population," the authors of the research said.
"Although studies have shown that the risk of death from recurrence decreases with increasing time since 5-year survival, uncertainty about the long-term risks of death from other causes remains. Investigations into long-term cause-specific mortality are important because any excess mortality may be related to long-term complications of treatment," they added.
It is also unsure if an increased mortality risk exists beyond 25 years from initial cancer diagnosis.
Raoul C. Reulen of the University of Birmingham, England examined long-term cause-specific mortality among 17,981 5-year survivors of childhood cancer, who were diagnosed with cancer before age 15 years between 1940 and 1991 in Britain and followed up until the end of 2006.
Overall, there were 3,049 deaths during the study period. Survivors experienced 11 times the number of deaths expected from the general population (standardized mortality ratio [SMR], 10.7). The SMR declined with follow-up but was still 3-fold higher than expected 45 years from diagnosis.
The absolute excess risk (AER) for deaths from recurrence declined from diagnosis at age 5 to 14 years to beyond 45 years from diagnosis.
"Beyond 45 years from diagnosis, recurrence accounted for 7 percent of the excess number of deaths observed while second primary cancers and circulatory deaths together accounted for 77 percent," authors of the report have written.
The researchers also said that that the excess mortality due to second primary cancer and circulatory disease is likely attributable to late complications of treatment.
"Second primary cancers are a recognized 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," researchers said.
The study was published in the Journal of The American Medical Association.