Longer Life Expectancy for Childhood Cancer Survivors

Study shows childhood cancer survivors can likely expect to have a longer life expectancy due to improvements in treatment over a 30-year period.

A goal of current and recent clinical trials in childhood cancer is to reduce the intensity of effective treatment with radiotherapy and with some chemotherapies to reduce later long-term side effects. The trials have shown that reduced treatment exposures are associated with a lower risk of premature death among survivors in the 15 years after their initial diagnosis. But researchers don’t yet know how these reduced treatment exposures affect overall life expectancy for childhood cancer survivors.

The Research

Jennifer Yeh, PhD, and her co-workers received support from an American Cancer Society (ACS) research grant to learn more about life expectancy for people who were first diagnosed with childhood cancer across 3 decades, between the years 1970 to 1999. They specifically were interested in whether the improvements in treatment and care are lengthening the shortened life expectancy of childhood cancer survivors.

In their recently published results, Yeh’s research team described their work method, cohort simulation. Cohort simulation uses a hypothetical or computer-generated (simulated) group of people to estimate the trends of certain diseases over a period of time. Their model created hypothetical cohorts of 5-year survivors of childhood cancer that were representative of participants in the Childhood Cancer Survivor Study. For each cohort, they evaluated conditional life expectancy, defined as the number of years a 5-year cancer survivor can expect to live.

The data they studied came from reported cases of children and adolescents who were diagnosed with bone tumors, central nervous system tumors, Hodgkin lymphoma, leukemia, neuroblastoma, non-Hodgkin lymphoma, soft tissue sarcoma, and Wilms tumor.

They found that conditional life expectancy increased for people who were treated the most recently—with more advanced treatments. When the initial diagnosis was between:

• 1970 and 1979: Conditional life expectancy for 5-year survivors (average age about 13) was 48.5 more years, which is 16.5 fewer years (25% less), than someone without a history of childhood cancer.
• 1980 and 1989: Conditional life expectancy for 5-year survivors (average age about 12) was 53.7 more years, which is 12.3 fewer years (19% less), than someone without a history of childhood cancer.
• 1990 and 1999: Conditional life expectancy for 5-year survivors (average age about 12) was 57.1 more years, which is 9.2 fewer years (14% less) , than someone without a history of childhood cancer.

Yeh’s team also looked at survival and life expectancy for 4 different types of treatment. Compared to those without a history of childhood cancer, children who were diagnosed in the 1970s and treated with:

• No treatment or only surgery had a 7-year shorter life expectancy versus a 6-year shorter one when diagnosed in the 1990s.
• Chemotherapy alone had an 11-year shorter life expectancy versus a 6-year shorter one when diagnosed in the 1990s.
  
• Radiotherapy alone had a 21-year shorter conditional life expectancy versus an 18-year one when diagnosed in the 1990s.
• Chemotherapy and radiotherapy had an 18-year shorter conditional life expectancy versus a 15-year one when diagnosed in the 1990s.
  

Why Does it Matter

Although Yeh's team found improvements in life expectancy across treatment types, treatments involving radiotherapy showed the least improvement. This suggests that more and better treatment options are needed for cancer types that are currently best treated with radiation.

These findings also emphasize the importance for survivors of childhood cancer to have regular follow-up care and take action to reduce their risks of developing heart disease and new cancers. In Yeh’s study, these health conditions were the leading causes of death in all treatment subgroups.

Guidelines for care and follow-up care based on specific exposures during childhood are provided by the Children’s Oncology Group.