Does clinical trial participation improve survival?

Doctor examines cancer patient
Credit: Bill Branson

A new study suggests that access to clinical trials may be associated with survival in childhood cancers.

The research, published in Annals of Oncology, shows that survival in UK children with cancer has improved significantly since the late 1970s. And this improvement coincides with increased participation in clinical trials.

“The results of our study show that improvements in childhood cancer survival match those reported by the relevant clinical trials that were running between 1978 and 2005,” said study author Dr Charles Stiller, of the University of Oxford in the UK.

“During this time, there has been an increasing level of participation in trials, with around 90% of all children with many types of cancer enrolled, and this has been facilitated by the organization of care into specialist children’s cancer units. These developments have underpinned the substantial improvements in survival seen at the population level.”

Dr Stiller and his colleagues analyzed data on British children diagnosed with cancer between 1978 and 2005. All patients had been diagnosed before they reached the age of 15.

In total, there were 39,067 children. But the researchers focused on the 25,853 patients for whom there was a multicenter trial of first-line treatment open for at least 10 years during the study period.

The patients had been diagnosed with acute lymphoblastic leukemia (ALL), acute myeloid leukemia, Hodgkin or non-Hodgkin lymphoma, medulloblastoma, neuroblastoma, Wilms’ tumor, hepatoblastoma, osteosarcoma, Ewing’s sarcoma, rhabdomyosarcoma, or germ-cell tumors.
 
For each diagnostic category, there was an annual reduction in the risk of death that ranged from 2.7% for rhabdomyosarcoma to 12% for germ-cell tumors of the testes and ovaries.

“Examples of cancers where a really big difference was seen over the study period are ALL and hepatoblastoma,” Dr Stiller said. “ALL is the most frequent cancer in children. In 1978, only 49% of children survived for 5 years, but survival increased steadily throughout the study period and from each trial era to the next. By the end of this study, 90% of children were surviving 5 years from diagnosis, and most of them could be considered cured.”

Dr Stiller added that, in the years before the first worldwide trial for hepatoblastoma, two-thirds of children with this disease died. But now, three-quarters of patients survive.

“This study shows how the increase in the proportion of children taking part in trials has gone hand in hand with improvements in survival,” said study author Kathy Pritchard-Jones, MD, of University College London.

On the other hand, the researchers did not find evidence to suggest that the absence of a trial resulted in a worsening of survival.

But that may be because the periods without an open trial between 1978 and 2005 were short, and there were too few patients for formal comparisons. Regardless, the investigators said that additional research is needed to determine if patients who participate in clinical trials actually have better outcomes than those who do not.

“If no trial is available, it may not have an immediate effect on survival,” Dr Pritchard-Jones said. “However, if that situation were to persist for many years, one would predict that the rate of improvement of survival would cease, and children in the UK would no longer be receiving ‘cutting edge’ treatment at the international forefront of innovative thinking.”

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