Smita Bhatia has watched pediatric patients defeat cancer, only to see many of them grow into adult survivors confronting new deadly opponents: secondary cancers and serious health problems resulting from the lifesaving but toxic therapies they received as children.
Bhatia, M.D., M.P.H., is the Ruth Ziegler Chair in Population Sciences at City of Hope as well as the director of the Center for Cancer Survivorship. She lauds a new study in the Journal of the American Medical Association documenting that adult cancer survivors have an extraordinarily high incidence of these health issues.
"This is a seminal piece of work that for the first time demonstrates that among survivors of childhood cancer, who have been followed for an average of 25 years, the burden of morbidity is inordinately high," said Bhatia, who was not involved in the study.
"Curative therapy for pediatric malignancies has produced a growing population of adults formerly treated for childhood cancer who are at risk for health problems that appear to increase with aging," wrote first author Melissa M. Hudson, M.D., of St. Jude Children's Research Hospital and the University of Tennessee College of Medicine, Memphis.
The research marked the first time that a large population of survivors had been evaluated using a comprehensive systematic clinical assessment to determine the prevalence of chronic health conditions.
Researchers wanted to know the type and prevalence of these conditions, how many were linked to treatment-related exposures, and the impact of aging on these survivors – information that may influence future screening recommendations and earlier medical interventions.
The analysis included 1,713 adult survivors of childhood cancer who were diagnosed and treated between 1962 and 2001, who were enrolled in the St. Jude Lifetime Cohort Study since Oct. 1, 2007, and who underwent follow-up until Oct. 31, 2012. Survivors ranged from 18 to 60 years (average age was 32). The median time from diagnosis was 25 years (with a range of 10 to 47 years).
"In this clinically evaluated cohort, 98.2 percent of participants had a chronic health condition," researchers noted. "The overall cumulative prevalence of a chronic condition was estimated to be 95.5 percent by age 45 and 93.5 percent 35 years after diagnosis." At age 45 years, the estimated cumulative prevalence was 80.5 percent for a serious/disabling or life-threatening chronic condition.
Researchers examined the prevalence of adverse outcomes by organ systems. The most common problems were found in pulmonary, auditory, cardiac, endocrine and nervous system function and were detected in 20 percent or more of participants at risk.
"Among survivors at risk for adverse outcomes following specific cancer treatment modalities, the estimated cumulative prevalence at age 50 years was 21.6 percent for cardiomyopathy [an enlarged heart that can lead to heart failure], 83.5 percent for heart valve disorder, 81.3 percent for pulmonary dysfunction, 76.8 percent for pituitary dysfunction, 86.5 percent for hearing loss, 31.9 percent for primary ovarian failure, 31.1 percent for Leydig cell failure, and 40.9 percent for breast cancer," the authors wrote.
Researchers were struck by the prevalence of newly discovered neurocognitive and neurosensory deficits, heart valve disorders and pulmonary dysfunction – conditions usually materializing much later in life. "Considering that the median age of this cohort was only 32 years, these data are concerning and may indicate a pattern of accelerated or premature aging," they wrote.
"These data underscore the need for clinically focused monitoring, both for conditions that have significant morbidity if not detected and treated early, such as second malignancies and heart disease and also for those that if remediated can improve quality of life, such as hearing loss and vision deficits," they added.
Researchers believe that the collective data will help to guide and refine future health screening practices, and may help doctors intervene earlier to protect patients’ health.
"This study underscores the importance of lifelong medical follow-up of childhood cancer survivors," said Bhatia, a practice already embraced at City of Hope’s Childhood Cancer Survivorship Program.