Why Childhood Cancer Survival Rates Have Increased

Advanced chemotherapy and personalized treatment have boosted survival rates for childhood cancers

(RxWiki News) With increasing survival rates for many types of childhood cancers, some of these cancers are approaching cures. Several key events have made this possible.

A recent publication reviewing the history of treating childhood leukemia reported that advances in the treatment strategies over the last half century have been the driving force in increasing childhood cancer survival rates.

From the first use of chemotherapy medications for childhood leukemias to the reduction in amount of radiation used for therapy to personalized treatment based on individual genetics, the authors cited many factors that have contributed to the current successful treatments for childhood cancers.

"Discuss treatment options with your child’s oncologist."

Melissa M. Hudson, MD, from St Jude Children’s Research Hospital in Memphis, TN, co-authored this study that reviewed the scientific advancements that have brought childhood cancer survival rates to their current 80 percent overall five-year survival rate.

Childhood leukemias have made great strides toward a cure and were used as an example of treatment advances by the authors.

In the 1950s, clinical researchers first started to use methotrexate and agents that interfered with DNA. These medications were used individually and were not successful.

Based on the observation that tuberculosis was best treated with a combination of medications, the late 50s and early 60s brought the use of combination therapy for leukemia. These treatments did not bring lasting results either, however.

During the 1960s, vincristine, asparaginase, cyclophosphamide, daunorubicin and cytarabine were introduced as chemotherapeutic medications. Reluctance from physicians to use these powerful agents that poisoned children’s bone marrow and caused great suffering was common at this time.

The recognition during this time that there were different types of leukemia would eventually help hone in on what treatment worked with which type of leukemia.

The gold standard of treatment goal was set as complete remission, and the phases of treatment were also standardized. The phases emphasized getting the patient into remission and staying there while minimizing effects on the central nervous system, a complication that developed once the bone marrow was in remission and was no longer making leukemic cells.

A study called StudyV is credited with changing the direction of the treatment of childhood leukemia. Patients were given the maximum doses of a combination of chemotherapy medications that could be tolerated, along with radiation therapy. Also, more care was taken to protect the patients' central nervous system. Prednisone, vincristine, 6-mercaptopurine, methotrexate and cyclophosphamide were given in different combinations and times during this study.

Following this treatment protocol, 31 of 35 patients achieved complete remission and 50 percent became long-term survivors. A similar treatment approach is used today.

Later clinical trials in the 1970s showed that if intensive therapy was not started until remission was achieved, survival rates could be boosted to nearly 70 percent.

The authors noted that this extended survival highlighted long-term health problems caused by the treatments. From this observation, an emphasis on minimizing long-term effects of leukemia treatment on health was developed. This included examining medication dosages, such as for adriamycin, by adjusting dosages downward for children. Adriamycin is toxic to the heart muscle and lowering doses, when possible, was one step to decrease this damage in children.

Developments in the 1990s that identified genetic mutations in certain leukemias opened the door for therapies based on genetic targets.

A consequence of increasing childhood leukemia survival rates has been the creation of a group of people with a unique medical history.

“Clinical practice guidelines for the management of asymptomatic long-term survivors of childhood, adolescent, and young adult cancers have been organized by several groups to standardize the care of this medically vulnerable and growing population,” the authors remarked.

As advancements into causes and treatments continue, the study authors predicted, “These efforts will be critical to defining the optimal therapeutic approach that balances the attainment of cancer-free survival with prevention of long-term and late treatment toxicities, particularly life-threatening toxicities.”

This study was published in the April issue of the Journal of Clinical Oncology.

The authors declared no conflicts of interest.

Review Date: 
April 14, 2014