Where advanced cancer patients live affects the likelihood that they can enroll in a treatment clinical trial, a new study found.

Fewer than 10 percent of U.S. cancer patients participate in clinical trials, the authors note.

“Clinical trials are the basis for the vast majority of advances in cancer care, so, the only way to move the field forward is for patients to participate in clinical trials,” said lead author Dr. Matthew D. Galsky of the Icahn School of Medicine at Mount Sinai in New York.

“In addition, participation in clinical trials may offer patients access to a novel treatment, that ultimately goes on to markedly change the outlook for patients with the disease, but is not otherwise available outside of the context of a trial,” Galsky told Reuters Health by email.

Some data has suggested that patients who participate in clinical trials may have better outcomes regardless of the treatment they receive, which could be due to the very close follow-up, and strict guidelines, for management of patients enrolled in trials, he said.

Galsky and his coauthors used data from ClinicalTrials.gov to locate actively recruiting trials of first-line treatments for metastatic breast, prostate, colorectal and non-small cell lung cancer in September of 2012, which turned up 227 trials at 5,011 sites in the U.S.

The researchers then estimated how accessible those sites would be for cancer patients by calculating the drive time to the nearest site for each U.S. zip code. They also estimated how many people with metastatic cancer would likely be represented by that zip code using cancer mortality data from the Centers for Disease Control and Prevention.

Most patients with metastatic cancer die of the disease, so mortality data was assumed to accurately reflect most patients with those types of cancer.

At least half of U.S. patients with metastatic prostate and colorectal cancer would have to drive more than 60 minutes one way to access a clinical trial site, the authors write in JAMA Internal Medicine.

More than 35 percent of breast and non-small cell lung cancer patients would also have to drive more than an hour.

Drive times would be longest for patients in the central and southwest areas of the U.S.

Many patients will not meet eligibility criteria for the trial nearest them, and for rarer cancers, trial availability is likely worse, the authors write.

A 2007 survey found that most cancer patients are not willing to travel to participate in clinical trials.

Another study, from 2001, found that patients whom physicians considered to be good candidates for clinical trials frequently did not have an appropriate trials protocol available for their type of disease, or the patients declined the chance to be in a trial due to distance from the trial center or to insurance denial.

“Clinical trials offer several potential benefits for the patients who participate,” said Dr. Neal J. Meropol, of Case Western Reserve University and University Hospitals Case Medical Center in Cleveland, Ohio. He was not involved in the study.

“They provide access to a novel therapeutic opportunity, offer hope, and ensure careful attention from the team of nurses and doctors involved in the study,” Meropol told Reuters Health by email.

“All patients with cancer should consider a clinical trial as a potential treatment option, regardless of disease status, prior treatment, etc.,” Galsky said.

It is a myth that clinical trials should only be a last resort, Meropol said.

“Within the field, we often make a big deal about the fact that only 3 to 5 percent of patients with cancer in the U.S. enroll in clinical trials but if trials are not accessible to half of all patients, that has implications with regards to potential mitigation strategies,” Galsky said.

There are many ways to make clinical trials more accessible, he said.

“Regulatory and financial barriers to opening trials at multiple sites, including multiple community sites, need to be addressed to make this process much less burdensome,” Galsky said.

Telemedicine may help to connect cancer patients with clinical trials they otherwise might not have been able to reach, but that approach is still in the very early stages, he said.