New Yorkers buying a health plan on the state’s new insurance exchange should read the fine print if they’re interested in getting care at some of the city’s top hospitals.

Not all are participating in the new plans created by the Affordable Care Act.

As of this week, not one of the plans for sale on New York’s health benefit exchange would cover treatment at Memorial Sloan-Kettering Cancer Center, one of the world’s largest and most respected cancer hospitals.

That could mean that the 615,000 individuals and 450,000 small business employees expected to eventually get their insurance through the exchange would have to go someplace else for treatment, or pay the bill out of their own pockets.

Other premier city hospitals are in the networks of just a few of the new plans.

NYU Langone Medical Center has signed agreements with four of the 19 insurers doing business on the exchange.

NewYork-Presbyterian Hospital, which oversees the city’s biggest hospital system, has signed agreements with six insurers.

President Obama promised when the Affordable Care Act was enacted that people who liked their doctors could keep them, but the reality of the law both in New York and around the country is that the new, lower-cost policies it is creating sometimes have smaller provider networks than Medicare, Medicaid, or the plans people typically get through their employers.

Those narrower networks are a result of insurers trying to control costs and hospitals being cautious about agreeing to take new, untested insurance products.

A spokeswoman for NYU Langone, Lisa Greiner, said the hospital was taking a “semi-conservative” approach to participation and working only with insurers with “strong records in resolving enrollment and payment issues.”

The hospital also chose not to work with insurers that wanted to include the hospital, but not its doctors, in its treatment networks.

Negotiations at several hospitals were ongoing, and it is possible some insurer networks will grow by the time policies take effect on Jan. 1.

Sloan-Kettering spokeswoman Caitlin Suzanne Hoo, said Wednesday that the hospital was still talking with insurers.

“We want to be accessible and expect to be in network with one or more ACA plans,” she said. She added that patients currently undergoing care shouldn’t worry about a disruption. “We would never stop a patient’s treatment because of a change in insurance or financial situation.”

Empire Blue Cross and Blue Shield, one of the health plans that failed to reach an agreement with Sloan-Kettering, didn’t directly address why things hadn’t worked out, but hinted that cost was a factor.

“Our choices relating to network composition have been motivated by our goal of supporting access to a broad range of care on an affordable sustainable basis,” spokeswoman Deb Wiethop said in an email. “Affordability is key to a more focused network.”

Founded in 1884, Sloan-Kettering was the first hospital in the world dedicated solely to treating cancer. The faculty includes winners of prestigious science prizes. Its clinical research program is one of the country’s largest.

(AP)