Better treatment and follow-up are being credited with a reduction in the likelihood that survivors of childhood cancers will later die of illnesses caused by their therapy, such as new malignancies or cardiac or lung disease. The improvement over the past 30 years is due, in part, to the reduced use of radiation therapy and anthracyclines, a type of chemotherapy.
The findings came from an analysis of more than 34,000 participants in the federally funded Childhood Cancer Survivor Study, which found that, among those who have survived at least five years, all-cause mortality at 15 years after diagnosis has dropped from 12.4 percent to 6 percent.
The results were announced in a press briefing May 31 during the 2015 annual meeting of the American Society of Clinical Oncology, a gathering of nearly 30,000 oncology professionals in Chicago.
“To go back to the 1960s, less than 30 to 40 percent of children would survive cancer; currently, over 83 percent of children (with the disease) will become five-year survivors. It’s estimated that, at 2013, there were over 400,000 survivors in the population, and that by 2020 there will be over half a million,” said lead study author Gregory T. Armstrong, a pediatric oncologist at St. Jude Children’s Research Hospital. “However, these five-year survivors are still at risk for late effects and late mortality. Thus, strategies to reduce late effects by reducing treatment intensity have been used for several decades in an attempt to lower mortality rates and improve quality of life.”
According to previous research, up to 18 percent of five-year survivors of childhood cancer died within 30 years of diagnosis, Armstrong noted during his presentation. Such deaths are attributable to progression or recurrence of the primary cancer, external causes such as accidents or suicide, or other health-related causes – primarily, the late effects of cancer therapy, ASCO explained in a press release.
The study presented May 31 looked at the outcomes of a retrospective cohort of 34,043 patients, chosen from among participants of the Childhood Cancer Survivor Study, funded by the National Institutes of Health. Investigators used the National Death Index, a record of death information kept by state vital statistics offices, to determine which patients had died, and when, ASCO stated. All participating patients were diagnosed between 1970 and 1999, were younger than 21 years of age at diagnosis, and were followed for a median 21 years. Their cancers included leukemia, lymphoma, malignancies of the central nervous system, Wilms tumor, neuroblastoma, and soft-tissue or bone sarcoma, Armstrong said.
The study found that 3,958 patients (12 percent) died during their follow-up period, with 1,618 (41 percent) of those deaths due to “other health-related causes,” including the late effects of cancer therapy — in particular, secondary or recurrent cancers.