Cancer affects everyone, no matter their background or ethnicity.

Yet cancer clinical trials — research studies designed to test the safety and effectiveness of potential new treatments — don't always represent the full scope of the population.

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That's because there is a shortage of diverse clinical trial participants, a deficit that can affect efforts to treat and cure the disease in all patients, no matter their gender, race or ethnicity.

"When we study certain conditions, certain cancers, and we only use one population, we find out a lot about that population," says John M. Carethers, M.D., chair of internal medicine at Michigan Medicine, "but it says nothing about other populations."

For clinical trials to be most effective, diversity is key. Certain types of cancer are more prevalent in black or Hispanic Americans; some cancers behave differently in younger versus older people.

Increasing the number of people involved means researchers could get a clearer handle on how best to help everyone.

Some clinical trials involve comparing two types of treatment or trying a new use for a drug already approved by the Food and Drug Administration for a different cancer. Others involve drugs that are being administered to people for the first time after rigorous laboratory testing.

Each method can help researchers determine if a medication works more effectively than the current standard treatments.

Still, "we won't know until we compare it head-to-head," says Lori Pierce, M.D., a Michigan Medicine radiation oncologist.

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She and Carethers know that most patients might have questions about clinical trials.

They also acknowledge that minorities could have particular concerns in light of the Tuskegee syphilis experiment, a federally funded — and highly unethical — study that for 40 years only monitored hundreds of black men with syphilis despite the availability of treatment.

Such wrongdoing, the clinicians stress, is well in the past: "Everyone wants to be cured of their disease," Pierce says. "Clinical trials give everyone equal opportunity to do so."

To learn more about clinical trials at Michigan Medicine, call the Cancer AnswerLine at 1-800-865-1125.