Young patients with cancer and blood diseases will receive care under one roof at a new children’s hospital in a plan announced today to unify services now provided separately by Kaleida Health and Roswell Park Cancer Institute.

Officials from the two institutions signed a memorandum of understanding to dedicate a floor of a new hospital to Roswell Park’s pediatric hematology-oncology program.

Ground-breaking for the recently named John R. Oishei Children’s Hospital, a replacement for the Women & Children’s Hospital campus on Bryant Street in the Elmwood Village, is expected in the spring of 2013 on the downtown Buffalo Niagara Medical Campus.

Roswell Park and Women & Children’s have collaborated in the care of young cancer patients for nearly 40 years and, together, treat more than 80 percent of the children in Western New York with cancer and blood disorders, officials said.

Many of the patients receive specialty services at Roswell Park and complementary care at the children’s hospital. In 2011, this amounted to 618 hospital admissions and more than 5,300 clinic visits.

However, the institutions provide the care at separate facilities, requiring patients, families and staff to work in a system that has been an impediment to providing optimal treatment.

“It’s not the most efficient setup,” said Dr. Martin Brecher, chief of hematology oncology at Women & Children’s and chairman of pediatrics at Roswell Park. “This is a step forward and puts us in the forefront of providing care to these children.”