In this podcast, Dr. Melissa Hudson discusses some of the research on childhood cancer survivorship presented at ASCO’s 2015 Annual Meeting.
ASCO: You're listening to a podcast from Cancer.Net. This cancer information website is produced by the American Society of Clinical Oncology known as ASCO, the world's leading professional organization for doctors that care for people with cancer.
In today's podcast, we'll discuss some of the research on childhood cancer survivorship, presented at ASCO's 2015 annual meeting. This podcast will be led by Dr. Melissa Hudson, who is the director of the Cancer Survivor Division, co-leader of the Cancer Prevention and Control Program, and a member of the Department of Oncology at St. Jude Children's Research Hospital. Dr. Hudson is also an Associate Editor for Cancer.Net.
The ASCO annual meeting is the premier educational and scientific event where physicians, researchers, and other healthcare professionals gather to discuss the latest in cancer care and treatment. This Cancer.Net podcast helps put new research findings into context and explains what they mean for patients. ASCO would like to thank Dr. Hudson for summarizing this research.
Dr. Hudson: This is Dr. Melissa Hudson. I direct the Survivorship Division at St. Jude Children's Research Hospital in Memphis, Tennessee. I would like to highlight two research studies presented at the 2015 annual meeting of the American Society of Clinical Oncology that I think are important for all pediatric cancer clinicians, patients, and their families. Both studies feature data from the Childhood Cancer Survivor Study, known as CCSS for short. The CCSS is a large cohort study of pediatric cancer survivors diagnosed between 1970 and 1999 who were treated at 31 cancer centers in the United States and Canada. CCSS researchers have been tracking the health of now over 30,000 survivors in the cohort for more than 20 years. To be eligible for this study, participants have to be alive at five years from their pediatric cancer diagnosis. One of the strengths of the study is the detailed cancer treatment information available on all participants, including total doses of chemotherapy and doses of radiation therapy to specific organs.
In the first study presented at ASCO, CCSS researchers looked at changes that have occurred over time in treatment of cancer patients and specifically provide key information both within and across types of pediatric cancers. This type of information is critical to link the health problems reported by long-term survivors in the cohort to specific treatments. Their results show that the type and intensity of treatments changed significantly over the past 30 years. The use of chemotherapy has significantly increased overall for all types of pediatric cancer except for childhood leukemia, which was always 100% treated with chemotherapy. But the total doses of chemotherapy that have been linked to serious side effects like heart muscle problems or infertility have actually decreased during that time. Exposure to radiation therapy significantly decreased for all pediatric cancer types except for soft tissue sarcoma. For example, among Hodgkin lymphoma survivors, chest radiation exposure was reduced and the use of higher dose radiation declined dramatically from 85% to 6% over the study period. The second study used this treatment information to evaluate the death rates and causes of death among childhood cancer patients who had survived at least five years from their cancer diagnosis. We know that there's been remarkable improvement in survival of childhood cancer over the past 50 years. In the 1960s, less than 30 to 40% of children diagnosed with cancer achieved five years survival. Now, over 80% of children diagnosed with cancer will become a five-year or long-term survivor of their disease. Many factors have contributed to this progress in survival, including improvements in surgical techniques, advances in the delivery of radiotherapy, the use of combination chemotherapy, as well as progress in supportive care. Because of these advances, five years survival rates approach or exceed 90% for certain pediatric cancers like Hodgkin lymphoma, Wilms' tumor, and standard-risk acute lymphoblastic leukemia.
Despite this progress, previous research has shown that childhood cancer survivors who reach the five-year milestone have a higher risk of death or late mortality compared to individuals in the general population who have not been treated for cancer. In the first 15 to 20 years after cancer diagnosis, recurrent cancer remains the most common cause of death, but by 30 years from diagnosis, health conditions other than the original pediatric cancer become the leading cause of late mortality. These conditions include late effects of childhood cancers such as new cancers that are different from the original pediatric cancer and other medical problems like heart and blood vessel disease. It is important to note that pediatric cancer researchers have made many changes in therapy, especially over the last 30 years, in an effort to prevent and reduce the risk of late complications and deaths from cancer treatments. Because of advances in understanding of cancer biology, cancer treatment is assigned based on risk of relapse. Children who are identified to be at low risk for relapse now receive less intensive therapy, whereas those who have a higher risk of relapse or poor response receive more intensive therapy. For example, most children with leukemia do not receive brain radiation, which previously was a lifesaving therapy to prevent or treat the leukemia spread in the central nervous system. Treatment of many cancers, like Hodgkin lymphoma, is based on the risk features of the disease and the response to therapy. This approach has helped reduce the number of children exposed to radiation and higher chemotherapy of doses observed in the first study. In addition to prompting changes in therapy for newly diagnosed children with cancer, understanding the late health problems or late effects that occur after treatment has also led to the development of health screening guidelines to promote early detection of late effects, improved treatment of late effects, and better supportive care to prevent late effects.
Because of the length between cancer treatment and late mortality, another goal of the second study was to look at how specific cancer treatments affected death rates. Results show that late mortality rates decrease significantly among survivors treated in the 1970s compared to those treated in the 1990s, at which point it was less than 6%. To further understand the reasons for this improvement in late mortality, the researchers looked at the causes of death. They noted that a late death from pediatric cancer recurrence declined to less than 4% among participants treated more recently, which reassure us that children treated more recently will stay in cancer remission if they reach that five-year milestone. Death rates from other health conditions also decline to less than 3% among survivors treated in more recent years. This includes deaths from late effects of cancer therapy. They specifically noted that the lower risk of death by treatment period was related to lower rates of death from new cancers - different from the original pediatric cancer - and health conditions like heart and lung disease. This decrease in late deaths was also directly related to a reduction in specific cancer chemotherapies and radiation therapies that have been highly linked to late effects. So for the first time, investigators from the childhood cancer survivors study show strong evidence that survivors treated in more recent eras have a significant reduction in late mortality, related to two factors - fewer deaths from recurrence of progression of the original pediatric cancer, as well as fewer deaths from treatment-related causes such as new second cancers and heart and lung disease. These results tell us that current treatment approaches that reduce the strength or intensity of therapy to lower the occurrence of late effects in addition to efforts to promote early detection and treatment of late effects has now led to a longer and healthier lifespan of survivors of childhood cancer.
ASCO: Thank you, Dr. Hudson. To find all of the science presented at ASCO's 2015 Annual Meeting, visit www.cancer.net. If you have questions about whether new research may affect your care, be sure to talk with your doctor.
Cancer.Net is supported by the Conquer Cancer Foundation, which is working to create a world free from the fear of cancer by funding breakthrough research, sharing knowledge with physicians and patients worldwide, and supporting initiatives to ensure that all people have access to high-quality cancer care. Thank you for listening to this Cancer.Net podcast.