People who have been treated for colon cancer are less likely to get chemotherapy after surgery to reduce the risk of future cancer if they have to travel far for the appointments, according to a new study.

Preventive chemotherapy given after cancer surgery to reduce the risk of recurrence is called “adjuvant” chemotherapy, and guidelines recommend that stage III colon cancer patients start receiving adjuvant chemo within three months of surgery.

In some cases in the study, “travel distance to treatment was really a barrier for patients to receive treatment,” said lead author Chun Chieh Lin of the American Cancer Society in Atlanta, Georgia.

“We tried to understand how oncologist availability in the area could be another barrier, and we found that for patients without private insurance, oncologists do make a difference,” she told Reuters Health by phone.

Her team analyzed data from close to 35,000 patients with stage III colon cancer diagnosed between 2007 and 2010. Three-quarters of them received adjuvant chemo within 90 days of cancer surgery.

As distance to the chemotherapy center increased, the likelihood of getting the chemo decreased. Patients who had to travel more than 250 miles were about 60 percent less likely to get it than those who had to travel less than 12.5 miles.

In most cases, patients would be traveling back to the facility where they had their cancer surgery to have adjuvant chemo.

The number of oncologists in the immediate vicinity of the patient’s home was not associated with the odds of receiving chemo. But patients with no insurance, and those with public insurance, were less likely to get chemo if they lived in an area with few oncologists.

For people with private insurance, oncologist density did not make a difference, the authors reported in the Journal of Clinical Oncology.

Oncologist density ranged from zero oncologists per 100,000 residents in rural areas like west Texas, to more than seven oncologists per 100,000 residents in areas like central Florida.

Patients who cannot afford private insurance might have less ability to travel to get chemo, or to take the necessary days off of work to get it, Lin said.

Dr. Daniel G. Haller, professor of medicine emeritus at the Abramson Cancer Center at the University of Pennsylvania, who was not part of the new study, pointed out that often, patients cannot drive themselves home after a chemotherapy session.

“If they don’t have close family members to drive them or cannot take one day off every two weeks twelve times, for a typical regimen, they may not get the treatment,” Haller told Reuters Health by phone.

Travel distance likely affects treatment for many conditions, like cardiac follow-up or diabetes, Haller said.

Adjuvant chemo is highly recommended for some, but not all, colon cancers, Lin said.

In the U.S. the average age at colon cancer diagnosis is 70, and many older patients may have other health conditions which preclude chemotherapy, or make it less likely that the chemotherapy will benefit them, Haller said.

“How many of those people were recommended to get chemo? You don’t know what was said after their surgery,” based on the data in this study, he said. Some patients might have been told not to get adjuvant chemo, he added.

But in some cases, patients are told to get adjuvant chemo but refuse, or do not have the social support to get to their appointments, Lin said.

“For the travel barrier, there are several things we can do to help patients,” including the patient navigator service available in many major cancer centers, she said.

A patient navigator works one-on-one with a cancer patient and identifies barriers to their care and how they can be overcome, she said. Navigators can contact physicians available in the local area or make appointments or find transportation assistance.

Some nonprofit organizations offer travel assistance as well, Lin said.