Referring cancer patients to the nation’s top oncology treatment centers has become increasingly difficult, according to a new study.

The reason? “Narrow network” insurance plans, which charge lower premiums but also restrict access to certain providers. The report in the Journal of Clinical Oncology says those plans are more likely to exclude doctors associated with National Cancer Institute (NCI)-Designated Cancer Centers.

"Because cancer care and monitoring is costly, there are strong incentives for insurers to be selective when it comes to oncologists, excluding those who are most likely to attract the most complex and expensive cases," explained lead author Laura Yasaitis, PhD, a postdoctoral researcher at the University of Pennsylvania’s Leonard Davis Institute of Health Economics.

The problem for patients and their regular healthcare providers is that price often is the biggest determinant when health insurance policies are purchased.

"Consumers may benefit financially from the fact that these narrow networks generally have lower premiums, but they may face reduced access to the higher-quality providers in their market," noted co-senior author Daniel Polsky, PhD, the executive director of the Leonard Davis Institute of Health Economics.

To reach those conclusions, the study team reviewed cancer provider networks offered on the 2014 individual health insurance exchanges to ascertain which oncologists were affiliated with NCI-Designated Cancer Centers or National Comprehensive Cancer Network (NCCN) Cancer Centers.

The study notes that NCCN Member Institutions are recognized for higher-quality care, and treatment at NCI-Designated Cancer Centers is associated with lower mortality than other hospitals. That especially is the case with severely ill patients and those with more advanced disease.

"To see such a robust result was surprising," Yasaitis said. "The finding that narrower networks were more likely to exclude NCI and NCCN oncologists was consistent no matter how we looked at it. This is not just a few networks. It's a clear trend."

The authors called for establishment of a standard exception process to allow patients to seek care out of network without incurring penalties in exceptional circumstances.