Cancer Studies Often Flawed

Cancer research often lacks rigor to answer key questions

(RxWiki News) The approval of a new cancer medication is always good news. But what if the research behind the medication’s approval isn't as strong as it could be? What if key questions aren't answered?

After reviewing thousands of cancer studies, a team of researchers suggested that cancer research is often less thorough and rigorous than research for other diseases.  

Cancer studies frequently involve fewer participants, and evaluate just one medication without comparing it to other available medicines.

The authors suggest that the push to get cancer medications to market as quickly as possible is behind these flaws.

"Consider participating in a clinical trial."

Researchers from Duke University in Raleigh-Durham, NC, and Knight Cancer Institute in Portland, OR, conducted an analysis of nearly 9,000 cancer clinical research studies.  Bradford Hirsch, MD, assistant professor of medicine at Duke, was the lead author.

The team examined studies that took place from 2007 to 2010. All were registered on the website.  

"We need to understand the strengths and weaknesses of the clinical studies in oncology,” Dr. Hirsch said in a press release.  He added that, since cancer is such a potentially grave disease, there are often few treatment alternatives.

“But what we're trying to understand is if those differences justify differences in the clinical research being conducted,” Dr. Hirsch said.

Here’s what the researchers uncovered about cancer clinical trials:

  • Cancer trials have fewer participants than other disease trials – a median of 51 vs. 72 patients.
  • Early phase (phase l and/or ll) were more common in oncology – 83 percent - compared to other diseases (51.6 percent)
  • More oncology studies tended to have ongoing recruitment (60.7 percent), compared to 42.3 percent among other disease trials.
  • Cancer studies were less likely to report completion of trials (10.7 percent), compared to 29.9 percent in other disease trials.
  • Oncology trials were also more likely to be single arm (meaning there was only one group of patients studied) than other trials - 62.3 vs. 23.8 percent.
  • Cancer research was also less likely than other types of research to be randomized (where groups are randomly assigned to have one medication, a placebo or another medicine) – 63.9 vs. 22.7 percent and open label (meaning both participants and researchers know which drugs are being given) – 87.8 vs. 47.3 percent).
  • Studies relating to cancer also rely more on what researchers call “surrogate endpoints.” Rather than looking at overall survival, for example, studies may look at progression-free survival, the length of time before the disease starts to get worse.

This review also uncovered an imbalance in where researcher dollars are focused.

  • Lung cancer has the highest incidence 14.5 percent and highest mortality 27.6 percent of all cancers, but was represented in only 9.2 percent of cancer trials.
  • Bladder cancer is also underrepresented; it’s being studied in only 1.1 percent of trials despite incidence and mortality rates of 4.6 percent. 
  • Breast cancer research adequately represents its incidence, though not its mortality.
  • And lymphoma research – 6.6 percent of all studies – is higher than either its incidence (4.8 percent) or its mortality rate (3.8 percent).

These differences can be explained, in part, by the accelerated approval the US Food and Drug Administration adopted in 1992. The goal of this program is to improve access to medications for life-threatening diseases.

“There are significant variations between clinical trials in oncology and other diseases, as well as among trials within oncology. The differences must be better understood to improve the impact of cancer research on clinical practice and the use of constrained resources,” the authors concluded.

Findings from this study were published April 29 in JAMA Internal Medicine. The study was funded by a FDA grant provided to the Clinical Trials Transformation Initiative. A number of the authors disclosed financial relationships with a number of organizations, including pharmaceutical manufacturers.

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Review Date: 
April 29, 2013