Will the observed shortened life expectancy of adult survivors of childhood cancer
lengthen over time given improvements in treatment and care? Using a simulation model–based
approach, this study estimates that children who received a diagnosis of and were
treated for cancer in the 1990s will live longer into adulthood than those diagnosed
in the 1970s. Despite improvements, these individuals remain at risk for a shortened
lifespan owing to severe treatment-related late toxic effects. Evolving treatment
approaches are projected to be associated with improved life expectancy after treatment
for pediatric cancer, in particular among individuals who did not receive radiotherapy
during childhood cancer treatment. Advances in childhood and adolescent cancer treatment
have been associated with increased rates of cure during the past 3 decades; however,
improvement in adult life expectancy for these individuals has not yet been reported.
To project long-term survival and assess whether life expectancy will improve among
adult survivors of childhood cancer who were treated in more recent decades. A microsimulation
model of competing mortality risks was developed using data from the Childhood Cancer
Survivor Study on 5-year survivors of childhood cancer diagnosed between 1970 and
1999. The model included (1) late recurrence, (2) treatment-related late effects (health-related
[subsequent cancers, cardiac events, pulmonary conditions, and other] and external
causes), and (3) US background mortality rates. Treatment subgroups (no treatment
or surgery only, chemotherapy alone, radiotherapy alone, and radiotherapy with chemotherapy)
and individuals with acute lymphoblastic leukemia during childhood by era (1970-1979,
1980-1989, and 1990-1999). Conditional life expectancy (defined as the number of years
a 5-year survivor can expect to live), cumulative cause-specific mortality risk, and
10-year mortality risks conditional on attaining ages of 30, 40, 50, and 60 years.
Among the hypothetical cohort of 5-year survivors of childhood cancer representative
of the Childhood Cancer Survivor Study participants (44% female and 56% male; mean
[SD] age at diagnosis, 7.3 [5.6] years), conditional life expectancy was 48.5 years
(95% uncertainty interval [UI], 47.6-49.6 years) for 5-year survivors diagnosed in
1970-1979, 53.7 years (95% UI, 52.6-54.7 years) for those diagnosed in 1980-1989,
and 57.1 years (95% UI, 55.9-58.1 years) for those diagnosed in 1990-1999. Compared
with individuals without a history of cancer, these results represented a gap in life
expectancy of 25% (95% UI, 24%-27%) (16.5 years [95% UI, 15.5-17.5 years]) for those
diagnosed in 1970-1979, 19% (95% UI, 17%-20%) (12.3 years [95% UI, 11.3-13.4 years])
for those diagnosed in 1980-1989, and 14% (95% UI, 13%-16%) (9.2 years [95% UI, 8.3-10.4
years]) for those diagnosed in 1990-1999. During the 3 decades, the proportion of
survivors treated with chemotherapy alone increased (from 18% in 1970-1979 to 54%
in 1990-1999), and the life expectancy gap in this chemotherapy-alone group decreased
from 11.0 years (95% UI, 9.0-13.1 years) to 6.0 years (95% UI, 4.5-7.6 years). In
contrast, during the same time frame, only modest improvements in the gap in life
expectancy were projected for survivors treated with radiotherapy (21.0 years [95%
UI, 18.5-23.2 years] to 17.6 years [95% UI, 14.2-21.2 years]) or with radiotherapy
and chemotherapy (17.9 years [95% UI, 16.7-19.2 years] to 14.8 years [95% UI, 13.1-16.7
years]). For the largest group of survivors by diagnosis—those with acute lymphoblastic
leukemia—the gap in life expectancy decreased from 14.7 years (95% UI, 12.8-16.5 years)
in 1970-1979 to 8.0 years (95% UI, 6.2-9.7 years). Evolving treatment approaches are
projected to be associated with improved life expectancy after treatment for pediatric
cancer, in particular among those who received chemotherapy alone for their childhood
cancer diagnosis. Despite improvements, survivors remain at risk for shorter lifespans,
especially when radiotherapy was included as part of their childhood cancer treatment.
This decision analytical model–based study uses data from the Childhood Cancer Survivor
Study to project long-term survival and assess whether life expectancy will improve
among adult survivors of childhood cancer who were treated in more recent decades.