Does size matter for cancer clinical trials?

Does size matter for cancer clinical trials?
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There’s been much discussion recently among cancer specialists regarding the importance of the size of the clinical trials that help to determine the newest, most effective, and safest cancer therapies.

And one study coming out of this week’s American Society of Clinical Oncology (ASCO) annual meeting in Chicago — called TAILORx and described as the largest breast cancer treatment trial ever held with more than 10,000 women — demonstrated how many women with early stage breast cancer can avoid chemotherapy altogether.

But while larger studies can provide greater statistical confidence, are they always necessary in this age of precision oncology and personalized medicine?


We have been attending ASCO meetings for several decades now and have witnessed how scientific and medical advances have helped swell the number of cancer survivors in America to more than 15 million in 2016, with that number expected to grow to about 20 million by 2026, according to the American Cancer Society.

We’ve also seen the number of adults participating in cancer clinical trials remain at less than 5 percent over those many years, with minorities and the underserved representing only a small percentage of that total.

There are many reasons for this including the exclusion of many patients due to co-morbidities — or other medical conditions present in addition to the cancer, as well as lack of information about various studies, and lack of understanding and fear of what cancer clinical trials do and don’t do.

During a 10-year period (from 2005-2015) the number of National Institutes of Health-sponsored clinical trials has decreased 41 percent from 1580 to 930, due to a flat federal budget and the rising cost of trials. And there has also been competition from industry-sponsored trials.

The debate over whether trials should involve many patients or just a few depends on many factors, but key to designing any clinical trial is including the goals and nature of individual trials so both have their place in finding better therapeutics to deal with the more than 200 types of cancer.

At ASCO its chief medical officer, Richard Schilsky, M.D. said what factors influenced the size of each cancer clinical trial.

He told us that one cannot look at clinical trials in a vacuum. They have to be viewed in the context of what scientific objective you are pursuing and what hypothesis you are testing.   

The trial design and the patient population have to be developed with those things in mind so you do the right trial to test the hypothesis in the most rigorous way for the target population of the intervention being studied, he said. Or, to simplify the concept, he added that you wouldn’t enroll breast cancer patients when studying a prostate cancer drug.

There may be applications for smaller, faster, more nimble trials during early stage testing or for some targeted therapies tailored to each patient’s specific genetic makeup.  

However, the most important thing to consider is whether each individual patient is being matched with the most appropriate available trial, and that requires careful scrutiny by oncology professionals willing and able to take the time to do what’s best for the patient, and not just for the clinical trials. 

And, of course, any subsequent successful treatments that are developed should be affordable and available to all who need them.

Nancy G. Brinker is a global cancer advocate and the founder of Susan G. Komen, the world's largest breast cancer charity name after her sister. She has also served as U.S. ambassador to Hungary, U.S. chief of protocol and as a Goodwill Ambassador for Cancer Control to the U.N.'s World Health Organization. Find her on Twitter: @NancyGBrinker.  Eric T. Rosenthal is a writer and  founder of the National Cancer Institute-Designated Cancer Centers Public Affairs Network. Find him on Twitter: @etrosenthal.