CHICAGO -- Patients with pancreatic cancer that hadn't spread lived substantially longer on a four-drug combo than on a single standard cancer drug,

It's a rare advance for a tough-to-beat cancer, and experts say it could be practice-changing for a small group of patients whose pancreatic cancer is diagnosed early enough to be removed by surgery.

Results were reported Monday at a medical meeting in Chicago.

The study tested folfirinox against the standard treatment, Gemzar. Folfirinox combines four chemotherapy drugs.

Two-thirds of patients given folfirinox were alive after three years versus half of those given Gemzar.

Nearly 500 patients in France and Canada were enrolled.