Experts See Progress, Hope in Battle Against Childhood Cancers
Article date: September 1, 2010
By: Eleni Berger
At the age of 7, Anna Pike is already a veteran of the war against cancer. Diagnosed with acute lymphocytic leukemia (ALL) when she was just a toddler, the second-grader from Michigan has spent much of her young life in treatment.
The first round lasted two-and-a-half years. When her cancer returned early last year, Anna’s family sought out the experts at St. Jude Children’s Research Hospital in Memphis, Tennessee.
“She’s responding really well to treatment, which we’re thankful for,” says her mother, Ann Marie. “She’s surrounded by kids that are like her and it’s very comforting to her.”
Benefitting from clinical trials
Anna is being treated as part of a clinical trial, an approach that many experts credit with dramatically improving the outlook for children with cancer over the past 50 years.
Clinical trials allow doctors to systematically study and compare treatments – including the side effects they cause – so that therapy can be refined and improved.
“We’re continually asking the question: Is this the best medicine, is this the best combination? We emphasize what works and doing what works with the fewest side effects,” says Maura O’Leary, MD, administrative officer for the Children’s Oncology Group, a collection of researchers, doctors, and other healthcare professionals focused on research and treatment of childhood cancer.
In fact, most children with cancer in the United States are now treated either in an active clinical trial, or with the most successful treatment discovered in the most recent study of their type of cancer, O’Leary says.
Rising survival rates
Statistics bear out the success of this strategy. Before the 1970s less than 50% of children with cancer survived 5 years after diagnosis, according to the American Cancer Society’s Cancer Facts & Figures 2010, an annual estimate of cancer incidence and death rates. Today around 80% of kids make it to the 5-year mark. More than 10,000 children 14 and under are diagnosed with cancer each year.
A recent review in the Journal of Clinical Oncology co-authored by O’Leary and colleagues from the Children’s Oncology Group (COG), the National Cancer Institute (NCI), and other institutions also shows that survival rates for all types of childhood cancers increased between 1975 and 2006.
Better treatments discovered in that period prevented 38,000 deaths from childhood cancer, they estimate.
Success against leukemia
Much of the improvement in survival has come in treating leukemia, the most common form of cancer in children. Progress has been especially great in ALL, the most common type of childhood leukemia.
"ALL and AML [acute myeloid leukemia], non-Hodgkin lymphoma, and gonadal cancer have made substantial gains in the past two decades,” says Anna’s doctor, Ching-Hon Pui, MD, an American Cancer Society Professor who is chair of the Department of Oncology at St. Jude.
Indeed, the NCI/COG review found that the 5-year surival rate for ALL in kids under 15 has risen from about 61% in 1975-1978 to more than 88% in 1999-2002 (the most recent years for which statistics are available). Likewise, the survival rate for kids under 15 with AML increased from less than 20% in 1975-1978 to 58% in 1999-2002.
Other cancers with survival rates that rose between the 1970s and the 2000s include non-Hodgkin lymphoma (now 88%), Hodgkin lymphoma (about 95%), Wilms tumor (over 90%), and the brain tumor medulloblastoma (73%).
Supportive care key
In addition to improved cancer drugs and treatment strategies, Pui credits improvements in supportive care with helping to boost survival rates and improve quality of life for kids during and after treatment – no matter what kind of cancer they may have.
More effective pain treatments, antiemetics, antifungal medications, and antibiotics mean cancer treatment is less unpleasant and safer than in the past, he says. It is now rare, for instance, for leukemia patients to die because of infections that can result from treatment, and doctors are better able to control nausea and vomiting these days.
"Children now come to the hospital to play, not to suffer,” Pui says.
Slower progress against some cancers
Unfortunately, not every type of childhood cancer has seen the dramatic improvement in survival rates as leukemia and Hodgkin lymphoma. Better therapies have been few and far between for some types of childhood cancer.
" For many solid tumors, the progress is pretty disappointing, except for gonadal cancer and neuroblastoma,” says Pui. ”Rhabdomyosarcoma, Ewing sarcoma and osteosarcoma have practically seen no improvement in outcomes in the last 20 years.”
The NCI/COG research bears this out. Survival rates for rhabdomyosarcoma, osteosarcoma and Ewing sarcoma have been relatively flat since the 1980s. Only modest progress has been made against most brain tumors, too.
International cooperation on uncommon cancers
One stumbling block to better outcomes is how rare many of these cancers are. Osteosarcoma, for instance, affects about 400 children each year, and Ewing sarcoma affects about 200. Brain tumors are more common, but there are many different types, each of which requires different therapy.
The relatively low number of children affected makes it hard to carry out definitive clinical trials to compare promising treatments, say O’Leary and her co-authors. However, there is a growing trend toward international collaboration in research on these rarer cancers that experts hope will spur progress.
New therapies needed
Experts also agree that new therapies are desperately needed to make the next big improvement in the outlook for children with cancer.
"I think people have pushed existing chemotherapy to the limit,” says Pui. "We’re still trying to improve conventional chemotherapy with better formulations, longer-acting ones, less toxic drugs. But chemotherapy is not specific – it can still damage normal organ tissues. So the thing to do is targeted and personalized therapy. ”
Targeted therapies are drugs that work on very specific proteins or other parts of cancer cells that are different from normal cells. Because of this, they may work in some cases when chemotherapy doesn't. In other cases they may be used along with chemotherapy to help it work better. Targeted drugs also tend to do less damage to normal cells, usually resulting in fewer side effects than traditional chemotherapy.
Examples of successful targeted therapies include imatinib (Gleevec) for certain types of leukemia, and trastuzumab (Herceptin) for some forms of breast cancer. Most of these newer drugs were first tested and used in cancers in adults. But as researchers have learned that certain childhood cancers share some of these same gene or protein targets, they have begun to test these medicines in childhood cancers as well.
Another area of intensive research is gene sequencing – looking for the specific DNA mutations that occur with different types of cancer. The hope is that identifying those mutations will provide information that could lead to new treatments.
The National Cancer Institute is spearheading one such project called TARGET. St. Jude is pursuing another in conjunction with Washington University School of Medicine in St. Louis.
The American Cancer Society also is funding multiple research projects studying the genetic patterns of several types of childhood cancers, including leukemia, neuroblastoma, lymphoma, osteosarcoma, and brain tumors.
These are just some of the 47 research grants the American Cancer Society is currently funding specifically related to childhood cancer. Others include research into how certain childhood cancers spread or become resistant to drugs, how to improve follow-up care for kids after cancer treatment, and how to help families better cope when a child is diagnosed with cancer. Research into other types of cancer may also turn out to be applicable against childhood cancers.
Pui, for one, is hopeful that these new avenues of research and collaboration will pay big dividends.
"Pediatric oncologists are overall curing almost 75% to 80% of all children combined,” he says. "In the coming decade I’m hopeful that we will be approaching 90% overall because we are a very disciplined group of investigators.”
Reviewed by members of the ACS Medical Content Staff
Citation: "Outcomes for Children and Adolescents with Cancer: Challenges for the Twenty-First Century." Published in the May 20, 2010 issue of Journal of Clinical Oncology. First author: Malcolm A. Smith, National Cancer Institute.
ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.
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